Solutions Manual for Automotive Technology A Systems Approach 8th Edition By Jack Erjavec, Rob Thomp

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 1: CAREERS IN THE AUTOMOTIVE INDUSTRY

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 1-1 ............................................................................................................ 6 CONCEPT ACTIVITY 1-2............................................................................................................ 7 CONCEPT ACTIVITY 1-3............................................................................................................ 7 CONCEPT ACTIVITY 1-4............................................................................................................ 8

SHORT ANSWER 1.

List at least five different types of businesses that hire technicians. Describe the types of work these businesses handle and the advantages and disadvantages of working for them.

Answer There are a variety of types of businesses that employ automotive technicians.

• Dealerships provide repair and maintenance on vehicles while they are under warranty and beyond. They offer the technician good technical support, special diagnostic equipment, an opportunity to specialize, and ongoing training. A disadvantage could be becoming limited to one or two particular model lines.

• Independent repair shops service all types of vehicles, sometimes specializing in certain areas of repair, or in either import or domestic vehicles. This type of shop may present constant service and diagnostic challenges to the technician, providing an opportunity to gain a well-rounded technical background. Disadvantages may include less sophisticated diagnostic equipment and less dealership-sponsored training.

• Store-associated shops provide certain specialized services such as brakes, exhaust systems, and wheel and tire repair. An advantage to the technician is the ability to specialize in one area and product. A disadvantage is the lack of opportunity in becoming as well rounded in other areas of automotive service.

• Specialty service shops provide repairs in specialized repair areas such as engine rebuilding, transmission/transaxle overhauling, brake, exhaust, emissions, or electrical systems. Technicians can become very skilled in the specialized area, but they can also limit themselves.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

•

Fleet service and maintenance shops provide service and maintenance for a fleet of company-owned vehicles. Their technicians can become very familiar with a wide range of vehicles over an extended period of time.

2. Name the different ways to gain work experience while you are a student.

Answer There are many ways that you can gain work experience while you are a student. They include the following: • job shadowing • mentoring • cooperative education • apprenticeship • part-time employment 3. Explain the implied difference between someone who is called a mechanic and one who is called an automotive technician.

Answer The term mechanic stresses the ability to repair and service mechanical systems. A technician must have that same mechanical knowledge plus an understanding of other technologies, such as electronics, hydraulics, and pneumatics.

4. Explain the basic requirements for becoming a successful automotive technician.

Answer To become a successful automotive technician, one must be able to master and keep up with the latest technologies and possess the skills to work well with people.

5. Describe a cooperative education program.

Answer A cooperative program is when the student alternates between going to school and going to work.

6. Explain what a new car warranty is and the two different types of warranties provided with a new car or truck.

Answer A warranty is a guarantee from the manufacturer that the vehicle will be free of problems, and if any problems do arise, the manufacturer will pay the cost of repairs.

New car warranties include the Federal Emissions Defect Warranty and the Federal Emissions Performance Warranty.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

7. List three things that service technicians must be able to do regularly.

Answer Diagnose vehicle problems, perform necessary tests, competently repair or replace faulty components.

8. What are the requirements for obtaining ASE certification?

Answer Passing an ASE test and having a minimum of two years of work experience.

MULTIPLE CHOICE 1.

Which of the following have had a significant impact on the automotive industry? a. Emission laws b. Electronics c. New technologies d. All of the above Answer: d. All of the above. Electronics are widely used because they allow for rapid response to changes in technology and vehicle operating conditions; they are inexpensive, lightweight, and very reliable. Legislation has set requirements for safety, emissions, and fuel consumption. Manufacturers must meet the current standards; doing so has affected the design of current vehicles.

2. Individuals often begin a career as an automotive technician in a new car dealership by ___, which is a good way for a new technician to become familiar with the vehicles sold at the dealership. a. working at the parts counter b. performing new car prep c. being a service advisor d. serving as the lead tech Answer: b. Often individuals begin their career as an automotive technician in a new car dealership by performing new car prep.

3. Technician A says a hybrid vehicle uses two different power sources. Technician B says a hybrid vehicle may use either a gas engine or electric motor to drive the wheels. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A typical hybrid vehicle has electric motors and an engine, both of which can be used to move the vehicle.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

4. The government-mandated warranty that specifically covers the catalytic converter(s) and engine control module is the ___. a. Federal Emissions Defect Warranty b. Federal Powertrain Warranty c. Federal Emissions Performance Warranty d. Extended Federal Exhaust Warranty Answer: c. The Federal Emissions Performance Warranty covers the catalytic converter(s) and engine control module for a period of 8 years or 80,000 miles.

5. Which of the following is typically included in a scheduled preventive maintenance program? a. Oil and filter changes b. Coolant and lubrication services c. Replacement of filters d. All of the above Answer: d. Scheduled preventive maintenance normally includes oil and filter changes, coolant and lubrication services, replacement of belts and hoses, and replacement of spark plugs, filters, and worn electrical parts.

6. In a large new car dealership, the individual who oversees the operation of the service department, parts department, and body shop is the ___. a. service manager b. service director c. shop foreman d. parts manager Answer: b. In a large new car dealership, the service director oversees the operation of the service department, parts department, and the body shop.

7. Repair work on a system covered by the manufacturer’s warranty is usually performed by ___. a. independent service shops b. dealerships c. specialty shops d. either A or B Answer: b. While a vehicle is still under warranty, repairs are usually performed in dealership service departments.

8. Which of the following businesses perform work on only one or two automotive systems? a. Dealerships b. Independent service shops c. Specialty shops d. Fleet service departments Answer: c. Specialty shops perform work on one or more automotive systems.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

9. Normally, whose job is it to greet the customer and complete the repair or work order? a. Service manager b. Parts manager c. Automotive technician d. Service advisor Answer: d. The service advisor normally greets the customer and gathers information for the repair order.

10. Technician A says that all an individual needs to do in order to become certified by ASE in a particular area is to pass the certification exam in that area. Technician B says that the questions on an ASE exam often force the test taker to choose between two distinct repair methods. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. After an individual passes a particular certification exam, he or she has only satisfactorily completed the voluntary exam requirement for certification in that test area, but must still complete the work experience requirement before he or she can be certified. Many ASE certification questions force the student to choose between two distinct repair or diagnostic methods.

11. To be successful, today’s automotive technician must have ___. a. an understanding of electronics b. the ability to repair and service mechanical systems c. the dedication to always be learning something new d. all of the above Answer: d. A successful technician must possess each of the skills listed.

12. A technician must have a minimum of ___ year(s) of hands-on work experience to get ASE certification. a. 1 b. 2 c. 3 d. 4 Answer: b. Two years of work experience are required to complete ASE certification.

Two years of formal training count as one of the two required years of hands-on experience.

13. An experienced technician who passes all eight basic ASE automotive certification tests is certified as a(n) ___. a. automotive technician b. master automotive technician c. service manager d. parts manager Answer: b. Master automotive technicians are certified in all eight ASE areas. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

14. Technician A says battery warranties are often prorated. Technician B says some warranties have a deductible. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Batteries and other automotive parts have prorated warranties. Some warranty conditions require the customer to pay a deductible and the warranty pays the remainder of the costs.

15. Wholesale auto parts stores that sell aftermarket parts and supplies to service shops and the general public are called ___. a. warehouse distributors b. mass merchandisers c. jobbers d. freelancers Answer: c. Aftermarket parts stores that sell to both the general public and to service shops are referred to as jobbers. Warehouse distributors do not generally sell to the general public, and mass merchandisers selling automotive products are retail outlets.

16. Ongoing technical training and support is available from ___. a. aftermarket parts manufacturers b. auto manufacturers c. online resources d. all of the above Answer: d. Technical training and support is supplied by original equipment manufacturers (OEMs), aftermarket parts manufacturers, jobbers, tool and equipment suppliers, online resources and others.

TECH MANUAL CONCEPT ACTIVITY 1-1 Explore the Automotive Industry Use an Occupation Outlook Handbook or go to the online version at http://www.bls.gov/OOH/ to gain additional information about automotive service technicians. Automotive technicians are listed under the heading of Installation, Maintenance, and Repair occupations.

1.

Describe some of the work performed by automotive service technicians.

Answer Answers may vary: Automotive technicians often identify mechanical problems, test parts and systems, follow checklists, perform basic care and maintenance services,

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

repair or replace worn parts, disassemble and reassemble parts, use testing equipment, and talk to clients.

2. Describe the job outlook for automotive technicians.

Answer Projected to grow faster than average, demand will increase as the number of vehicles in service increases.

3. What is the income range for technicians?

Answer Average pay was over $36,000; the lowest 10 percent earned less than $20,000, and the highest 10 percent earned over $60,000.

CONCEPT ACTIVITY 1-2 Explore Job Opportunities Search for automotive technician job openings in your area. It is common for dealerships and larger shops to place their job openings on their websites. In addition, local media websites will have job postings. Create a list of three of these jobs, and describe what skills, experience, and certifications are required for each.

Job 1: __________ Job 2: __________ Job 3: __________ Do you see yourself, in the next year or two, in one of the jobs you found? Consider these jobs and think about your personal education and career goals. What will you need to do to accomplish these goals?

Answer Answers will vary based on location but should include skills required for working in the industry.

CONCEPT ACTIVITY 1-3 Explore Training and Education Options 1.

If you are a high school student, make a list of colleges or other postsecondary schools in your area that offer automotive training.

Answer Answers will vary based on location.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 1: Careers in the Automotive Industry

2. If you are a postsecondary student, list what type of automotive training programs are available at the school you attend.

Answer Answers will vary based on location but may include Ford ASSET, Toyota T-TEN, GM ASEP or similar.

3. Determine what education and training opportunities are available in your area from sources other than schools. For example, list any local automotive parts suppliers that offer training for technicians.

Answer Answers will vary based on location but may include NAPA, Carquest, or similar companies.

CONCEPT ACTIVITY 1-4 Explore ASE Certification Visit the ASE website at www.ase.com and explore certification.

1.

What are the requirements to become an ASE certified technician?

Answer Pass an ASE test and have a minimum of two years’ work experience. One year of work experience can be substituted by two years of formal automotive training.

2. Which areas of ASE certification interest you the most and why?

Answer Answers may vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 2: Workplace Skills

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 2: WORKPLACE SKILLS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 Tech Manual ........................................................................................................................ 5 CONCEPT ACTIVITY 2-1 ............................................................................................................ 5 CONCEPT ACTIVITY 2-2 ........................................................................................................... 6

SHORT ANSWER 1. What type of information should go into your employment plan?

Answer Your employment plan should include your specific job goals and a plan to reach them.

You should list your interests, skills, and attitudes that match the job you are seeking.

Include both your short-term and long-term goals along with a prioritized list of potential employers.

2. Explain three types of pay systems used for technicians.

Answer Technicians are normally paid by hourly wages, commission, flat rate, or with a team system.

3. What should be included in the three main paragraphs of a cover letter?

Answer Your cover letter should include three paragraphs. The first should describe your interest in working for this employer and the position you are seeking. The second paragraph is used to sell yourself, and the third is used as a closing by thanking the employer and requesting an interview.

4. If you decide that leaving your job is the best way to relieve stress at work, describe the steps you should take to end your employment.

Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 2: Workplace Skills

If you decide that leaving your job is the best solution, do it professionally. Do not simply stop showing up for work or walk up to the employer and say “I quit!” The best way to quit a job is to write a letter of resignation and personally present it to the employer. The letter should state why you are leaving the company. Be careful not to attack the business, the employer, or fellow workers. The letter should also include the last day you intend to work. Your last day should be approximately two weeks after you notify the employer. At the end of your letter of resignation, thank the employer for the opportunity to work for him or her and for the personal growth experiences they provided for you.

5. Describe the seven basic steps for logical diagnosis.

Answer The seven basic steps for logical diagnosis are: 1) 2) 3)

4)

5) 6) 7)

Gather information about the problem. Find out when and where the problem happens and what exactly happens.

Verify that the problem exists. Take the vehicle for a road test and try to duplicate the problem, if possible.

Thoroughly define what the problem is and when it occurs. Pay strict attention to the conditions present when the problem happens. Also pay attention to the entire vehicle; another problem may be evident to you that was not evident to the customer.

Research all available information to determine the possible causes of the problem. Try to match the exact problem with a symptoms chart or think about what is happening and match a system or some components to the problem.

Isolate the problem by testing. Narrow down the probable causes of the problem by checking the obvious or easy-to-check items.

Continue testing to pinpoint the cause of the problem. Once you know where the problem should be, test until you find it!

Locate and repair the problem, then verify the repair. Never assume that your work solved the original problem. Make sure the problem is history before returning it to the customer.

6. List the characteristics of a good resume.

Answer A good resume is neat, uncluttered, and easy to read on quality white paper. It is also short and tells your story. It should contain dynamic words to describe your skills and experience. The information provided in it should be accurate. The most important information should stand out and be positioned near the top of the page. It should be free of spelling and grammatical errors.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 2: Workplace Skills

7. List four responsibilities of the employee in the employee–employer relationship.

Answer Regular attendance, following directions, team membership, responsibility, productivity, and loyalty 8. Describe the difference between verbal and nonverbal communication.

Answer Verbal communication is things that you actually say. Non-verbal communication includes things like posture, eye contact, and appearance.

9. Explain several characteristics of positive interpersonal relationships.

Answer Answers will vary but may include options such as suggesting improvements, displaying a positive attitude, working in a team toward common goals. One must exercise “give and take” for the benefit of the business, value diversity, respond to praise and criticism professionally, provide constructive praise or criticism, resolve conflicts professionally, and identify and react to intimidation or harassment.

MULTIPLE CHOICE 1.

Which of the following is not a recommended step for accurate diagnosis of a problem? a. Gather as much information as you can about the problem. b. Thoroughly define the problem. c. Replace system components and identify the cause of a problem through the process of elimination. d. Research all available information and knowledge to determine the possible causes of the problem.

Answer: c. Deciding to replace components using a process of elimination until the problem is repaired is not part of an accurate diagnosis.

2. Which of the following behaviors does not show that you are a responsible person? a. Having set goals and priorities in your work and personal life b. Showing a willingness to follow rules, regulations, and policies c. Showing a willingness to share the consequences of your mistakes with others d. Using ethical reasoning when making decisions Answer: c. A responsible person does not attempt to avoid the consequences of his mistakes or share the blame with others.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 2: Workplace Skills

3. Which of the following is not the right thing to do when you are being interviewed for a job? a. Show up looking neat and in clothing more formal than what you would wear on the job. b. Think carefully about your responses before answering questions. c. To avoid saying too much or offending the interviewer, answer as many questions as you can with a simple yes or no. d. Listen closely to the interviewer and look at the interviewer while they talk.

Answer: c. Never answer questions with a simple “yes” or “no.”

4. Which of the following is not a characteristic of a good employee? a. Reliable b. Responsible c. Overly sociable d. Loyal Answer: c. A good employee should be reliable, responsible, and loyal. Being sociable can be a good characteristic, but should not interfere with productivity.

5. Applicant A goes to a quiet place immediately after an interview and reflects on what just took place. Applicant B sends a letter of thanks to the interviewer if he has not heard back from the employer within two weeks. Who is doing the right thing? a. A only b. B only c. Both A and B d. Neither A nor B Answer: a. After an interview, you should reflect on what took place in order to do better next time. A letter of thanks should be sent to the employer within three days after the interview, not within two weeks as stated by Applicant B. 6. Technician A always looks at people while they are speaking and listens to their message before responding. Technician B always looks at customers when they are speaking to show she is interested in what they are saying. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. You should not only look at people while they are speaking to you but also listen carefully and try to fully comprehend the message.

7. Technician A always speaks to customers with his arms folded across his chest because he does not know what else to do with them. Technician B always tries to fully comprehend the message by asking questions about it and gathering as many details as possible. Who is correct? a. Technician A only b. Technician B only c. Both A and B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 2: Workplace Skills

d. Neither A nor B Answer: b. Try to fully comprehend messages by asking questions and gathering details. Folding your arms is a nonverbal communication indicating rejection of the message.

8. Which of the following would not be considered a soft skill? a. Enjoying solving puzzles or problems b. Caring for or helping people c. The ability to work independently d. Taking care to follow orders or instructions Answer: a. Soft skills are personal skills that are part of your personality and are used while relating to other people. Enjoyment of solving puzzles or problems is a technical skill rather than a personal skill.

9. When identifying individuals to use as references while seeking employment, consider all the following except: a. someone who knows you and who is respected in your community, such as a club leader or elected official. b. a family member or close friend. c. past and present teachers, coaches, and school administrators. d. people you have worked for or have helped.

Answer: b. A family member or close friend is not a good reference since he/she will not be seen as offering an objective view of you.

TECH MANUAL CONCEPT ACTIVITY 2-1 Create an Employment Plan Create an employment plan by honestly appraising yourself and your goals.

Employment goals: ___________________________________ Time frame to meet employment goals: ___________________________________ Skills, both automotive and others: ___________________________________ List of potential employers: ___________________________________ Personal strengths related to goals: ___________________________________ Areas requiring improvement: ___________________________________ Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 2: Workplace Skills

Answers will vary based on each individual student but may include the following: Finding full time employment Six months to one year Basic auto repair and soft skills Dealerships and independent shops Good hands-on skills Getting to work on time

CONCEPT ACTIVITY 2-2 Preparing a Résumé Prepare a résumé that includes the following elements: contact information, career objectives, skills and/or accomplishments, work experience, education, and a statement about references. To help with this, résumé templates are available in Microsoft Word and on the Internet.

Answer Resumes will vary based on each student but should contain items shown in text example.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 3: BASIC THEORIES AND MATH

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 4 Tech Manual ........................................................................................................................ 5 CONCEPT ACTIVITY 3-1 ............................................................................................................ 5 CONCEPT ACTIVITY 3-2 ........................................................................................................... 7 CONCEPT ACTIVITY 3-3 ........................................................................................................... 7 CONCEPT ACTIVITY 3-4 ........................................................................................................... 8 CONCEPT ACTIVITY 3-5 ........................................................................................................... 8 CONCEPT ACTIVITY 3-6 ........................................................................................................... 9 CONCEPT ACTIVITY 3-7 ........................................................................................................... 9 CONCEPT ACTIVITY 3-8 .......................................................................................................... 11 CONCEPT ACTIVITY 3-9 .......................................................................................................... 11 CONCEPT ACTIVITY 3-10 ........................................................................................................ 13 CONCEPT ACTIVITY 3-11 ......................................................................................................... 14 CONCEPT ACTIVITY 3-12......................................................................................................... 15

SHORT ANSWER 1.

Describe Newton’s first law of motion and give an application of this law in automotive theory.

Answer Newton’s first law of motion is referred to as inertia. It means that an object at rest tends to remain at rest, and an object in motion tends to remain in motion unless some force acts on it. For example, when a car is parked on a level street, it remains stationary unless it is driven or pushed.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

2. In what four states does matter exist? Cite examples of each.

Answer All matter exists as a gas, liquid, solid, or plasma. Students’ examples of each state will vary.

3. Explain Newton’s second law of motion and give an example of how this law is used in automotive theory.

Answer Newton’s second law states that when a force acts on an object, the motion of the object will change. The change in motion is proportional to the amount of force applied and the mass of the object. For example, a truck has greater mass than an automobile, so it requires a larger engine to provide the force needed to drive it.

4. Describe five different forms of energy conversions in an automobile.

Answer There are many different forms of energy: chemical, electrical, mechanical, thermal, radiant, and nuclear.

5. Describe four different types of energy conversion.

Answer Types of energy conversion commonly used in automobiles are chemical-to-thermal energy (as in the combustion of the fuel); chemical-to-electrical energy (as in the battery); electrical-to-mechanical energy (as in the starter); thermal-to-mechanical energy (as in an internal combustion engine); mechanical-to-electrical energy (as in an alternator or AC generator); and electrical-to-radiant energy (as in lighting).

6. Explain why a rotating, tilted wheel moves in the direction of the tilt.

Answer A rotating, tilted wheel will move in the direction of the tilt because the side of the wheel opposite the direction of the tilt has a larger diameter and circumference, causing it to travel a greater distance in one revolution. This difference in distance traveled pushes the wheel in the direction of the tilt.

7. Why are gases and liquids considered fluids?

Answer Gases and liquids are considered fluids because they move or flow easily and easily respond to pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

8. Describe how out-of-balance forces can affect the automobile.

Answer The effects of static and dynamic balance will be the absence or reduction of vibration. Static imbalance can result in a condition referred to as tramp, and a dynamic imbalance can result in a wobble or shimmy.

9. Describe the effect of pressure on an enclosed volume of a gas.

Answer According to Charles’ law, the volume of an enclosed mass of gas depends on its temperature. The higher the temperature, the greater the volume.

10. Explain why elastic mounts are used to connect the engine to the frame.

Answer Engines are mounted in a vehicle using flexible mounts to reduce the transfer of vibrations.

11. Name three types of simple machines.

Answer Inclined plane, pulley, lever, gear, and wheel and axle 12. Define the coefficient of friction and how it relates to modern brake system design.

Answer The force needed to move the objects compared to the mass of the objects is called the coefficient of friction. The coefficient of friction between the brake parts plays a part in how effective the brakes operate. Too much friction causes the brakes to grab and too little friction causes long stopping distances and excessive heat.

13. Explain work, torque, and horsepower.

Answer Work is performed when a force moves a mass a specific distance. Torque is a force that tends to twist or rotate things, and it is measured by the force applied over the distance traveled. Horsepower is the measurement of the rate at which work is done.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

MULTIPLE CHOICE 1.

Which of the following is the correct formula used to calculate engine displacement? a. Displacement = π × R2 × L × N b. Displacement = π2 × R × L × N c. Displacement = π × D × L × N d. Displacement = π × D × L2 × N Answer: a. Displacement = π × R2 × L × N is correct.

2. While discussing different types of energy: Technician A says that when energy is released to do work, it is called potential energy. Technician B says that stored energy is referred to as kinetic energy. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Stored energy is called potential energy, and energy that is released to do work is called kinetic energy.

3. While discussing friction in matter: Technician A says that friction creates heat.

Technician B says that friction only occurs with solids and is not present with liquids and gases. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Friction does create heat and will occur in liquids, solids, and gases.

4. While discussing mass and weight: Technician A says that mass is the measurement of an object’s inertia. Technician B says that mass and weight may be measured in cubic inches. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Mass is the amount of matter in an object.

Weight is measured in pounds or kilograms.

5. When applying the principles of work and force, ___. a. work is accomplished when force is applied to an object that does not move b. in the metric system the measurement for work is cubic centimeters c. no work is accomplished when an object is stopped by mechanical force d. if a 50-pound object is moved 10 feet, 500 ft.-lb of work are produced Answer: d. If a 50-pound object is moved 10 feet, 500 ft.-lb of work are produced.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

6. All these statements about energy and energy conversion are true, except ___. a. thermal energy may be defined as light energy b. chemical to thermal energy conversion occurs when gasoline burns c. mechanical energy is defined as the ability to do work d. mechanical-to-electrical energy conversion occurs when the engine drives the generator Answer: a. Thermal energy may be defined as light energy.

7. Which of the following is not a true statement about heat transfer? a. Whenever the temperature of something changes, a transfer of heat has occurred. b. Conduction is the transfer of heat by infrared rays. c. Light bulbs are examples of heat transfer by radiation. d. Convection occurs when a hot object moves to an area with less heat.

Answer: b. Conduction takes place when the heat of an object is transferred to another by closeness.

TECH MANUAL CONCEPT ACTIVITY 3-1 Heat 1.

Place some cold tap water into a glass or similar container. Place a thermometer into the water and record its temperature. ________________________ °F (°C) Answer Students will record changes in temperature of tap water over time when ice is added and when heat is added.

2. Next, place some ice into the water, and note the water temperature every few minutes until you achieve the lowest steady reading.

Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Answer Students will record changes in temperature of tap water over time when ice is added and when heat is added.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

3. What is the lowest temperature the water reached?

Answer Answers will vary but should exceed 32 °F/ 0 °C. 4. Why does the water not get any colder?

Answer Students should be able to explain how the principles of heat transfer and latent heat will prevent the water from getting colder than 32 °F/ 0 °C. 5. What would need to take place to cause the entire quantity of water to freeze?

Answer Answers will vary.

When water is heated to its boiling point, 212 °F (100 °C), the heat causes the water to turn to a vapor. Ask permission to perform this activity before continuing. Boiling water can cause severe burns and serious injury.

6. Measure the water temperature, and then begin to heat a pan or beaker of water while observing the temperature with an appropriate thermometer.

Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Time ________________________ Temperature °F (°C) ________________________ Answer Answers will vary.

7. What is the highest temperature the water reached?

Answer Students should report 212 °F or 100 °C. 8. Why does the water not get any hotter?

Answer At the boiling point, any heat added to the water is latent heat and will cause phase change but will not raise the temperature further.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

9. What happens to the quantity of water as it boils?

Answer The volume of water decreases as it turns to gas.

CONCEPT ACTIVITY 3-2 Energy Conversion Match each of the following types of energy conversion with its corresponding component.

Chemical to thermal Chemical to electrical Electrical to mechanical Thermal to mechanical Electrical to radiant Mechanical to thermal Mechanical to electrical

Headlight Window motor Air/fuel burning Brake pad Battery Combustion Generator

Answer Chemical to thermal = air/fuel burning Chemical to electrical = battery Electrical to mechanical = window motor Thermal to mechanical = combustion Electrical to radiant = headlight Mechanical to thermal = brake pads Mechanical to electrical = generator

CONCEPT ACTIVITY 3-3 Vehicle Design 1.

List three important factors that have influenced modern vehicle design: Answer

Passenger safety, reduced emissions, and increased efficiency 2. Describe what features you think may be found on cars and trucks 10 to 20 years from today.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

CONCEPT ACTIVITY 3-4 Newton’s Laws 1.

Describe another automotive situation to which Newton’s first law applies.

Answer Answers will vary but could include responses such as seat belts, air bags.

2. Using Newton’s f = ma equation, determine the amount of force needed to push a 4,000-pound car two miles per hour.

Answer 8,000 foot-pounds 3. Describe another application of Newton’s third law of motion.

Answer Answers will vary but may include responses such as a spring absorbing and releasing energy when a vehicle hits a bump or a sliding/floating caliper design.

CONCEPT ACTIVITY 3-5 Friction 1.

Think about your experiences with automobiles, and list as many examples of friction as possible.

Answer Answers will vary but may include examples such as changing oil and brake pads; tires, and seat cushions.

The amount of friction between two objects is dependent upon the materials of which they are made and the force pushing the two surfaces together. The force needed to move the objects compared to the mass of the objects is called the coefficient of friction.

Imagine that you have a large square block of rubber in your lab that weighs 100 pounds.

2. How much force do you think would be needed to slide that block across the floor?

Answer Answers will vary but may include numbers up to 100 lbs. of force.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

If the required force is 100 pounds and the mass is 100 pounds, then the coefficient of friction would be equal to 100/100, or 1. Now imagine that you have a 100-pound block of ice sitting on the lab floor.

3. How much force do you think would be needed to slide the ice across the floor?

Answer Answers will vary but may include numbers such as 10 lbs. of force.

As you can imagine, moving the ice should be easier than moving the rubber; therefore, the coefficient of friction is lower. The automotive brake system relies on the coefficient of friction remaining consistent.

4. Describe how the brakes would operate if the coefficient of friction were too low.

Answer It will take longer to stop and the brakes may overheat.

5. Describe how the brakes would operate if the coefficient of friction were too high.

Answer The brakes may grab and lock the wheels.

CONCEPT ACTIVITY 3-6 Simple Machines 1.

Match each of the following simple machines with its common application: Screw Nail Pulley Wheelbarrow Wedge Ferris wheel Lever Crane Wheel and axle Playground slide Inclined plane Key ring Answer Screw – key ring, pulley – crane, wedge – nail, lever – wheel barrel, wheel and axle – Ferris wheel, inclined plane – playground slide

CONCEPT ACTIVITY 3-7 Torque and Horsepower 1.

How much force will need to be applied to a torque wrench 2 feet long to achieve a torque of 100 ft.-lb?

Answer 50 lbs

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

2. How much force will need to be applied to a torque wrench 0.5 m long to achieve a torque of 80 N-m?

Answer 40 N 3. How much force will need to be applied to a torque wrench 6 inches long to achieve a torque of 20 ft.-lb?

Answer 40 lbs Power is the measurement of the rate at which work is done. Power, expressed in watts, is a unit of speed combined with a unit of force. For example, if you pushed a cart with a force of 1 Newton at a speed of 1 meter per second, the power output would be 1 watt. The term watt is taken from James Watt, an English inventor, who is credited with calculating horsepower. By measuring the amount of weight a horse could move over distance and time, Watt derived the calculation of horsepower. By observing that a horse could move 330 pounds 100 feet in 1 minute, he calculated 1 horsepower as 33,000 ft.-lb per minute, or 550 ft.-lb per second (330 x 100 = 33,000 ft.-lb per minute). Two horsepower could do the same amount of work in half the time. (330 x 100 x 2 = 66,000 ft.-lb per minute; 66,000 ft.-lb per minute = 33,000 ft.-lb in 30 seconds.)

4. If you pushed a 3,000-pound car 11 feet in 15 seconds, how much horsepower did you produce?

Answer 4 hp To find the horsepower of an engine, use this formula: horsepower = torque x engine speed/5,252. The constant of 5,252 is used to convert rpm into revolutions per second.

(The constant 5,252 is a rounded-up quantity of the original formula used by James Watt based on one pound moving in a circle with a radius of one foot.) If an engine produces 250 ft.-lb of torque at 4,500 rpm, it will produce 214 hp at 4,500 rpm.

5. What is the horsepower of an engine with 300 ft.-lb of torque at 4,000 rpm?

Answer 228 hp As you can see, torque and horsepower are related. An engine that can produce maximum torque at higher rpm will be able to accelerate over a longer period of time than an engine that produces its maximum torque at a lower rpm.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

CONCEPT ACTIVITY 3-8 Vibrations and Sound 1.

List three components or systems that can cause unwanted vibrations on a vehicle.

Answer Wheels, tires, drive shafts, wheel bearings, cooling fan Sound is a result of vibrations, though some vibrations can occur at frequencies either below or above the human range of hearing. Frequency is the number of times a vibration occurs and is usually rated in hertz (Hz), which is the number of cycles per second. A sound with a vibration of 200 Hz will have 200 oscillations per second. A sound with a frequency of 2 kHz (kilohertz, or 2,000 Hz) will oscillate 2,000 times per second. The lower the hertz rate, the lower the frequency and the tone of the sound.

The higher the frequency, the higher pitched the sound will be. Humans can usually hear sounds between 20 Hz and 20,000 Hz. Being able to identify various sounds is an important diagnostic skill. By listening to a noise and its relation to engine speed or wheel speed, you can more easily locate the source of the problem.

2. A customer complains that there is a high-pitched rattling noise from her vehicle, which gets louder and increases in frequency when engine speed is increased. The noise occurs in park and while driving. Which of these is the most likely cause and why? a. Loose wheel bearings b. Loose drive belt c. Loose exhaust shield d. Loose motor mount Why? Answer c. Loose exhaust shield because the increased flow of the exhaust will vibrate the pipe faster with higher RPM.

CONCEPT ACTIVITY 3-9 Hydraulic Principles 1.

Label the forces of each piston in the diagram below (Figure 3-1):

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

FIGURE 3–1 Determine the output forces for each piston.

Master cylinder output pressure: ______________________________ Answer 10 lbs.

Output force of 4-inch piston: __________________________________ Answer 20 lbs.

Output force of 2-inch piston: __________________________________ Answer 10 lbs.

Output force of 1-inch piston: __________________________________ Answer 5 lbs.

2. Why do the disc brake calipers have much larger pistons than wheel cylinders?

Answer Disc brakes require greater output forces since they do not self-energize.

3. Why are the front caliper pistons larger than the rear caliper pistons on a four-wheel disc brake vehicle?

Answer Weight transfers to the front during braking.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

4. What other automotive systems use hydraulics to operate?

Answer Power steering, automatic transmissions 5. List three pieces of equipment in your automotive lab that utilize hydraulics.

Answer Answers will vary.

CONCEPT ACTIVITY 3-10 Vacuum and Pressure Attach a vacuum/pressure gauge to a 100-cc syringe (or similar). With the syringe plunger approximately half retracted and the gauge attached to the small opening, pull the plunger out farther, and note the reading on the gauge.

1.

Gauge reading: ____________________________ Answer Answers will vary.

2. Next, push the plunger in, and note the gauge reading.

Answer Answers will vary.

The change in pressure, both a decrease and an increase, are a result of changing the volume inside the syringe. By increasing the volume, the pressure decreased, and by decreasing the volume, the pressure increased. This is an example of Boyle’s Law. To test the Pressure Law, that the volume of a gas depends on its temperature, you will need a balloon or vacuum/pressure gauge, bottled water, and a heating element.

Place approximately 4 ounces of water in a 16-ounce water bottle and attach either a balloon or vacuum/pressure gauge to the opening of the container. Place the bottle of water into a separate container, and place on the heating element. Heat the water until it reaches boiling, and note the pressure reading on the gauge or note the balloon.

3. Pressure reading: ______________________________ or Balloon diameter: _____________________ Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

4. Why did the pressure in the balloon increase?

Answer Increased temperature increased the pressure.

5. What would happen to the pressure in the balloon if the water were cooled to the freezing point?

Answer It would decrease.

CONCEPT ACTIVITY 3-11 Chemical Reactions Obtain three rusted bolts from your instructor. Place one bolt in a container with tap water; place another bolt in a container with a carbonated soft drink; and place the third bolt in a container with tap water and baking soda. Monitor the condition of the bolts over several days and note their appearance.

Day 1

Bolt in water: _________________________ Bolt in soft drink: ______________________ Bolt in baking soda and water: ________________________

Day 2 Bolt in water: ________________________ Bolt in soft drink: _______________________ Bolt in baking soda and water: _____________________________ Day 3 Bolt in water: _________________________________ Bolt in soft drink: ______________________________ Bolt in baking soda and water: __________________________ Answer Answers will vary but may include reasons such as bolts in water may start to rust, or bolts in soft drinks and in baking soda may appear less rusty.

1.

Describe your findings on the bolts after several days of soaking in the three containers.

Answer Answers will vary but may include reasons such as bolts changed appearance based on composition of the bolt and the solution in which they were exposed to.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

2. Why do you think the bolts reacted the way they did?

Answer Answers will vary but may include reasons such as chemical reactions occurred between the material of the bolts and the solutions they were exposed to.

Students should be able to identify soft drinks as acidic compounds and baking soda as a basic (alkaline) compound. They should be able to describe the effects of acids and bases on metals.

CONCEPT ACTIVITY 3-12 Electromagnetism Obtain a magnetic compass or short finder from your instructor. Place the compass along a vehicle’s battery cable and turn on the headlights.

1.

What was the reaction of the compass?

Answer The compass should move.

2. Crank the engine over and note the compass while cranking. Was the response the same as with the headlights?

Answer The compass should move more.

3. How does increased current flow affect the compass?

Answer Increased current causes the compass to have a greater deflection of the needle.

Obtain a digital multimeter that can measure AC volts, a length of wire, and a magnet from your instructor. Position the wire and magnet so that you can attach the meter leads to the ends of the wire. The magnet must be able to pass very close to the wire so that the magnetic lines of force move perpendicular to the wire. Rapidly move the magnet back and forth near the wire and note the reading on the meter (Figure 3-2).

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 3: Basic Theories and Math

FIGURE 3–2 Electricity can be produced by moving a magnetic field over a conductor.

4. How much AC voltage was produced?

Answer Moving the magnet quickly should produce A/C voltage between 0 VAC and 1 VAC. 5. Move the magnet at a slower rate than before. How much AC voltage was produced?

Answer Slowing the magnet’s movement should reduce AC voltage.

6. Move the magnet quickly past the wire but at a great distance. How much AC voltage was produced?

If possible, add additional magnets and repeat.

Answer Increasing the magnet’s distance from the wire should decrease AC voltage.

7. Did the amount of AC voltage change with more magnets?

Answer Additional magnets should increase the amount of AC voltage.

8. What conclusions can you make about AC voltage induction based on this experiment?

Answer Students should describe how magnetic fields create current flow in a conductor.

As you complete the activities in this chapter, you should have furthered your understanding of some of the basic principles on which the automobile operates.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 4: AUTOMOTIVE SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 4-1............................................................................................................ 7 CONCEPT ACTIVITY 4-2 ........................................................................................................... 7 CONCEPT ACTIVITY 4-3 ........................................................................................................... 8 CONCEPT ACTIVITY 4-4 ........................................................................................................... 9 CONCEPT ACTIVITY 4-5 ........................................................................................................... 9

SHORT ANSWER 1.

Under the CAFE standards, for what are vehicles tested?

Answer The Corporate Average Fuel Economy (CAFE) standards require a certain fuel economy average for all vehicles produced by a manufacturer.

2. Explain the four strokes of the internal combustion engine.

Answer The four basic strokes of an internal combustion engine are the intake stroke where the fuel and air enters the cylinder, the compression stroke where the air and fuel are compressed, the power stroke that takes place after the air and fuel is ignited, and the exhaust stroke which forces the spent gases out of the cylinder.

3. In addition to the battery, what does the charging system include?

Answer In addition to the battery, a charging system should include a generator, voltage regulator, charge indicator light or gauge, and the necessary wiring.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

4. What is meant by the term regenerative braking?

Answer Regenerative brake systems convert the kinetic energy of the vehicle into electrical energy to recharge the vehicle’s high-voltage batteries.

5. Explain how an engine produces the power needed to move a vehicle.

Answer Answers will vary but may include these reasons: When the air and fuel mixture burns in the combustion chamber, a large amount of heat and pressure is generated. This pressure pushes down on the piston, which turns the crankshaft. The motion of the crankshaft turns the transmission and ultimately the drive wheels.

6. Describe three major types of engine cylinder configurations.

Answer Inline where each cylinder is inline with each other; V-type where the cylinder block is shaped in a V; and opposed where the cylinders lie flat and opposite each other.

7. Compare and contrast FWD and RWD drivetrain configurations.

Answer FWD drivetrains use a transaxle, which also contains the differential gears to drive the front wheels. RWD drivetrains have a separate transmission and differential assembly to drive the rear wheels.

MULTIPLE CHOICE 1.

Which of the following is not a commonly used emission control system? a. EGR b. PCV c. EVAP d. Air injection Answer: d. The air injection system was once commonly used, but due to advanced technologies, it is seldom found on current vehicles.

2. Automatic transmissions use a ___ instead of a clutch to transfer power from the flywheel to the transmission’s input shaft. a. differential b. U-joint c. torque converter d. constant velocity joint Answer: c. Automatic transmissions use torque converters instead of clutches.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

3. Which of the following is not one of the strokes of a four-cycle engine? a. Compression b. Exhaust c. Intake d. Ignition Answer: d. Ignition is a process, not a stroke; it is part of the power stroke.

4. Technician A says that the PCV system is designed to limit CO emissions. Technician B says that catalytic converters reduce HC emissions at the tailpipe. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The catalytic converter reduces HC, CO, and NOx emissions. The purpose of the PCV system is to reduce emissions of HC, not CO. 5. Which is not a common automotive fuel? a. Gasoline b. Diesel c. Hydrogen d. Ethanol Answer: c. Hydrogen is not currently used as an automotive fuel. It may be the primary source of fuel for fuel cells.

6. What does the valve train do? a. It delivers fuel to a device that controls the amount of fuel going to the engine. b. It houses the major parts of the engine. c. It converts reciprocating motion to rotary motion. d. It opens and closes the intake and exhaust ports of each cylinder.

Answer: d. The valve train opens and closes the intake and exhaust ports of each cylinder.

7. Technician A says that liquid cooling an engine helps to maintain a consistent operating temperature. Technician B says that oil is circulated through the cooling system to remove heat from the engine’s parts. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Liquid-cooled engines maintain a constant operating temperature. Oil does not circulate through the cooling system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

8. An engine will not start and no spark is found at the spark plugs when the engine is turned over by the starter. Technician A says that the problem is probably the battery.

Technician B says that the ignition system is most likely at fault. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The battery has sufficient power to crank the engine; therefore, the nospark condition is most likely caused by a faulty ignition system.

9. Which emission control system introduces exhaust gases into the intake air to reduce the formation of NOx in the combustion chamber? a. EVAP b. EGR c. Air injection d. PCV Answer: b. The exhaust gas recirculation (EGR) system introduces exhaust gases into the intake manifold in order to reduce NOx emissions.

10. Technician A says that many vehicles use an AC generator as the charging unit.

Technician B says that all vehicles use an alternator as the charging unit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. An alternator is an AC generator, so both technicians are correct.

11. Technician A says that a transaxle delivers torque to the front and the rear drive axles.

Technician B says that a transaxle is most commonly found in 4WD pickups and SUVs. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Transaxles are most commonly used to drive the front wheels of FWD vehicles.

12. Which of the following is not part of the running gear? a. Differential b. Steering c. Suspension d. Brakes Answer: a. The differential is part of the drivetrain.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

13. Which of the following statements about unibody construction is not true? a. A unibody is a stressed hull structure in which each of the body parts supplies structural support and strength to the entire vehicle. b. Unibody vehicles tend to be tightly constructed because the major parts are all welded together. c. All unibodies are constructed from steel. d. Most front-wheel-drive unibody vehicles have a cradle or partial frame.

Answer: c. Some unibody vehicles are constructed with aluminum.

14. Which type of transmission uses pulleys to change engine speed? a. Dual-clutch b. Manual c. Continuously variable d. Automatic Answer: c. Most continuously variable transmissions rely on pulleys and chains or belts to vary the engine’s speed sent to the drive wheels.

15. Which of the following components are used to dampen the upward and downward movement of a vehicle’s springs? a. Torsion bars b. Shock absorbers c. Constant velocity joints d. Connecting linkages Answer: b. Shock absorbers 16. What two major engine components work together to change the reciprocating motion of the pistons into a rotary motion? a. Crankshaft and connecting rod b. Camshaft and crankshaft c. Camshaft and connecting rod d. Crankshaft and valve train Answer: a. The reciprocating motion of the pistons is changed into a rotary motion by linking the pistons to the crankshaft with a connecting rod.

17. Technician A says that an air-conditioning system removes heat from inside the engine. Technician B says that the heating system removes heat from the inside of the vehicle. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The air-conditioning system removes heat from the passenger compartment. The heating system adds heat to the inside of the vehicle by transferring heat from the engine’s cooling system to the inside of the vehicle.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

18. The boiling point of the coolant in an engine’s cooling system is raised by the ___. a. thermostat b. pressure cap c. radiator d. water pump Answer: b. To raise the boiling point of the coolant, it is pressurized. The pressure cap maintains this pressure.

19. While discussing the operation of air-conditioning systems: Technician A says that in order for the refrigerant to release heat, it must be at a low temperature and pressure.

Technician B says that in order for the refrigerant to absorb heat, it must be at a high temperature and pressure. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The opposite is true in both cases.

20. While discussing HEVs: Technician A says that in a series hybrid, the engine is only used to power a generator to recharge the batteries. Technician B says that in a parallel hybrid, the engine and/or the battery can supply the power to move the vehicle. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A parallel hybrid electric vehicle uses either the electric motor or the gas engine to propel the vehicle, or both. Whereas, the engine in a true series hybrid electric vehicle is used only to drive the generator that keeps the batteries charged.

The vehicle is powered only by the electric motor(s).

21. Which of the following is not accomplished by the fuel and air system of a gasoline engine? a. Stores the fuel for later use b. Collects and cleans the outside air c. Delivers fuel to a device that will control the amount of fuel going to the engine d. Keeps the fuel and air ratio constant regardless of the conditions under which the engine is operating Answer: d. The fuel and air system must change the fuel and air ratios to meet the needs of the engine during different operating conditions.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

TECH MANUAL CONCEPT ACTIVITY 4-1 Automotive Design Influences Explain the three major influences in the design evolution of modern vehicles.

Answer The student answer should contain terms such as safety, emissions, and fuel economy.

CONCEPT ACTIVITY 4-2 Engine Design and Construction Using a vehicle in the lab, describe the following: Year ____________________Make ___________________Model_________________ a. b. c. d. e. f. g.

Engine design (inline, opposed, V, W): __________________________ Number of cylinders: __________________________ Fuel type (gasoline, diesel, E85, CNG): ________________________ Cylinder block construction material: _________________________ Cylinder head construction material: __________________________ Valvetrain design (OHV, OHC, DOHC): _____________________________ Intake manifold construction material: ________________________

Answer Answers will vary but may include the following: Vehicle year, make, and model a. Inline, V, or opposed b. 3, 4, 5, 6, 8, 10, 12 c. Gasoline, diesel, E85 d. Cast iron or aluminum e. Cast iron or aluminum f. Overhead cam, dual overhead cam, overhead valve g. Plastic, aluminum, cast iron

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

CONCEPT ACTIVITY 4-3 Identify Vehicle Fluids and Emission Devices Using a shop vehicle, locate the following information. Some of this information can be found on the vehicle emission control information (VECI) decal, shown in Figure 4-1.

Year ____________________ Make ___________________ Model_________________ a. b. c. d.

Recommended engine oil: _______________________ Recommended engine coolant: _______________________ Emission devices: _______________________ A/C refrigerant type and charge amount: _______________________

FIGURE 4–1 This image shows emissions equipment and family as well as emission system calibration information.

Answer Answers will vary but may include the following: Vehicle year, make, and model a. 0W20, 5W20 b. OAT, HOAT c. TWC, HO2S, EGR d. 134a, 1234yf

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 4: Automotive Systems

CONCEPT ACTIVITY 4-4 Identify Drivetrain Using a shop vehicle, locate the following information: Year ____________________ Make ___________________ Model_________________ a. Transmission type: ___________________ b. Drivetrain layout (FWD, RWD, 4WD, AWD): ___________________ c. Recommended transmission fluid: ___________________ Answer Answers will vary but may include the following: Vehicle year, make, and model a. Auto or manual transmission b. FWD, RWD, AWD, 4WD c. Dexron, ATF +, OE specific

CONCEPT ACTIVITY 4-5 Identify Suspension and Brake System Using a shop vehicle, locate the following information: Year ____________________ Make ___________________ Model_________________ a. b. c. d.

Front-suspension type (strut, SLA, multilink): ___________________________ Power-steering type (hydraulic or electric): ___________________________ Front and rear brake type: ___________________________ Recommended brake fluid type: ___________________________

Answer Answers will vary but may include the following: Vehicle year, make, and model a. MacPherson strut b. Hydraulic or electric c. Disc and drum d. DOT 3, DOT 4, OE specific

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 5: HAND TOOLS AND SHOP EQUIPMENT

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 5-1 ............................................................................................................ 7 CONCEPT ACTIVITY 5-2 ........................................................................................................... 7 CONCEPT ACTIVITY 5-3 ........................................................................................................... 8 CONCEPT ACTIVITY 5-4 ........................................................................................................... 9 CONCEPT ACTIVITY 5-5 ........................................................................................................... 9

SHORT ANSWER 1.

Explain how to properly use and care for a micrometer.

Answer The care and use of a micrometer is important: • Always clean the micrometer before using it.

• Do not touch the measuring surfaces.

• Store the tool properly. The spindle face should not touch the anvil face; a change in temperature might spring the micrometer.

• Clean the micrometer after use. Wipe it clean of any oil, dirt, or dust using a lintfree cloth.

• Never use the tool as a clamp or tighten the jaws too tightly around an object.

• Do not drop the tool.

• Check the calibration weekly and also right after you drop it.

2. List some common uses of the dial indicator.

Answer Use a dial indicator for such things as measuring valve lift, crankshaft endplay, flywheel or brake rotor runout, gear backlash, or crankshaft journal concentricity.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

3. Wrenches are available in several styles. List and describe three types of wrenches.

Answer The size of a wrench is determined by the distance between its jaws measured in inches or millimeters; there are open-end wrenches, box-end wrenches, combination wrenches, flare nut or line wrenches, Allen wrenches, and adjustable-end wrenches.

4. How do manufacturers inform technicians about changes in vehicle specifications and repair procedures during the model year?

Answer Service bulletins are used to update service information throughout the year.

5. List the steps that should be followed to precisely tighten a bolt to specifications.

Answer When using a torque wrench, follow these steps to get an accurate reading: 1) Locate the torque specs and procedures in a service manual.

2) Mentally divide the torque specification by three.

3) Hold the wrench so that it is at a 90-degree angle from the fastener being tightened.

4) Tighten the bolt or nut to one-third of the specification.

5) Then, tighten the bolt to two-thirds of the spec.

6) Now tighten the bolt to within 10 foot-pounds of the spec.

7) Tighten the bolt to the specified torque.

8) Recheck the torque.

6. Describe three sources of service information available to technicians.

Answer Service manual information is usually also made available by certain manufacturers in printed manuals, on CDs, DVDs, or via the Internet.

7. What is the main advantage of using a box-end wrench instead of an open-end wrench?

Answer A box-end wrench is less likely to slip off of the fastener and strip its head and scrape your knuckles.

8. What precision measuring tool should be used to check end play or out-of-roundness?

Answer A dial indicator

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

9. How do you determine where the proper lift points for a vehicle are?

Answer Check the service information or a lift guide.

MULTIPLE CHOICE 1.

Technician A says a metric bolt with the marking of 8.9 has more yield strength than a 10.9 bolt. Technician B says only grade 8 nuts should be used on 10.9 rated bolt. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The 8.9 bolt would have a tensile strength of 800 MPa and a yield strength of 720 MPa (90 percent of 800), while the 10.9 bolt would have a tensile strength of 1,000 MPa and a yield strength of 900 MPa (90 percent of 1,000). Grade 8 nuts are for US or English bolts, not for metric 10.9 grade bolts.

2. Which of the following wrenches is the best choice for torquing a bolt? a. Open-end b. Box-end c. Combination d. None of the above Answer: d. A torque wrench should be used for torquing a bolt.

3. Technician A says that a micrometer can be used to measure the outside diameter of something. Technician B says that a vernier caliper can be used to measure the diameter of a bore. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are right.

4. Technician A says that a tap cuts external threads. Technician B says that a die cuts internal threads. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is right. A tap is used to cut internal threads, and a die is used to cut external threads.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

5. Which of the following screwdrivers is like a Phillips but has a flatter and blunter tip? a. Standard b. Torx® c. Pozidriv® d. Clutch head Answer: c. A Pozidriv screwdriver is similar to a Phillips, but flatter and blunter.

6. Technician A says most US bolts have a thread pitch between 1.0 and 2.0 threads per millimeter. Technician B says 1.0 thread pitch is a finer thread than a 2.0 thread pitch.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The thread pitch of US bolts is the number of threads that are in 1 inch of the threaded length and is expressed in number of threads per inch. The distance, in millimeters, between two adjacent threads determines the thread pitch in the metric system. This distance will vary between 1.0 and 2.0 and depends on the diameter of the bolt. The lower the number, the closer the threads are placed and the finer the threads are.

7. Technician A uses a punch to align holes in parts during assembly. Technician B uses a chisel to drive out rivets. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A chisel is used to shear off the head of a rivet, not to drive it out. Punches are used to align holes and drive items out of a bore.

8. An extractor is used for removing broken ___. a. seals b. bushings c. pistons d. bolts Answer: d. An extractor is used to remove broken bolts.

9. Which of the following statements about items that are press fit is not true? a. Many precision gears and bearings have a slight interference fit when installed on a shaft or housing. b. The press fit allows slight motion between the parts and therefore prevents wear. c. The removal of gears and bearings that are press fit must be done carefully to avoid breaking or binding the parts. d. A puller with the proper jaws and adapters should be used when applying force to remove press-fit gears and bearings.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

Answer: b. Parts with a press fit should not have any relative motion between them.

10. Technician A uses a blowgun to blow off parts during cleaning. Technician B uses a blowgun to clean off his uniform after working. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Use a blowgun to blow off parts during cleaning, but never direct it toward a person.

11. Technician A says that flare nut or line wrenches should be used to loosen or tighten brake line or tubing fittings. Technician B says that open-end wrenches will surround the fitting’s nut and provide a positive grip on the fitting. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Flare nut wrenches are used for brake line and tubing fittings. Open-end wrenches do not have as many points of contact as a flare nut wrench, and therefore would not provide as positive a grip on the fitting.

12. Technician A uses a dial indicator to take inside and outside measurements.

Technician B uses a dial caliper to take inside, outside, and depth measurements. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A dial indicator is best used to measure the movement of something. A dial caliper may be used for inside, outside, and depth measurements.

13. For a measurement that must be made within one ten-thousandth of an inch, Technician A uses a machinist’s rule. For the same accuracy, Technician B uses a standard micrometer. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is right. A machinist rule is marked in 1/8″ (3.18 mm), 1/16″ (1.59 mm), 1/32″ (.79 mm), or 1/64″ (.40 mm), increments. Most micrometers are designed to measure objects with 0.001 (one-thousandth) of an inch accuracy. To measure an object with an accuracy of one ten-thousandth of an inch, a special micrometer is needed.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

14. Technician A says that jack stands should always be used with portable floor jacks.

Technician B says lifting capacity and operation should be checked before using a floor jack. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Jack stands should always be used when jacking up a vehicle, and all lifting equipment should be checked prior to use.

15. When using an air/electric impact wrench, Technician A uses impact sockets and adapters. Technician B uses chrome-plated sockets. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Impact sockets and adapters should be used with an air impact wrench.

16. While discussing thread sealants and lubricants: Technician A says that antiseize compound is used where a bolt might become difficult to remove after a period of time. Technician B says that thread sealants are used on bolts that are tightened into an oil cavity or coolant passage. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct.

17. The metric equivalent to 10 miles is ___. a. 0.06895 bar b. 10.6895 bars c. 1.6093 kilometers d. 16.093 kilometers Answer: d. A bar is a measurement of pressure, and one mile of distance equals 1.6093 kilometers.

18. Which of the following thread designs typically has tapered threads to provide for sealing at a joint? a. UNC b. NPT c. UNF d. UNEF Answer: b. NPT is the standard thread design for joining pipes and fittings. There are two basic designs: tapered and straight cut threads. Tapered pipe threads provide a

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

good seal because the internal and external threads compress against each other as the joint is tightened.

19. Which of the following is not measured with a feeler gauge set? a. Piston ring side clearance b. Flywheel runout c. Crankshaft end play d. Spark plug gap Answer: b. Flywheel runout is measured with a dial indicator.

TECH MANUAL CONCEPT ACTIVITY 5-1 Measurement Conversion Convert the measurements in the table below using the formulas given on page 107 in the textbook.

Answer 266.7 mm, 7.929 inches, .889 mm, .748 or ¾ inch, 108 n-m, 47 ft.-lb, 106.67 C, 102.2 F

CONCEPT ACTIVITY 5-2 Bolt Measurement Get an assortment of fasteners from your instructor. Identify each using the information in your Tech Manual and textbook. List the dimensions and grades below. Figure 5-1 provides an example of how bolts are measured.

Bolt 1: Length ___________ Diameter ___________Thread Pitch ___________Grade___________ Bolt 2:

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

Length ___________ Diameter ___________Thread Pitch ___________Grade___________ Bolt 3: Length ___________ Diameter ___________Thread Pitch ___________Grade___________ Bolt 4: Length ___________ Diameter ___________Thread Pitch ___________Grade___________ Bolt 5: Length ___________ Diameter ___________Thread Pitch ___________Grade___________ Bolt 6: Length ___________ Diameter ___________Thread Pitch ___________Grade___________

FIGURE 5–1 The shank diameter, the number of threads per inch, and the length are all used to determine SAE bolt size. Metric bolt size is similar, except thread pitch is measured as the space between each thread peak in millimeters.

Answer Answers will vary.

CONCEPT ACTIVITY 5-3 Using a Micrometer Using a micrometer, list the micrometer reading of the 10 drill shanks supplied by your instructor. The masking tape on the drill shank is covering up the actual drill size; do not remove the tape. The number on the masking tape is used as a reference while recording the drill shank sizes.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 5: Hand Tools and Shop Equipment

CONCEPT ACTIVITY 5-4 Using a Dial Indicator With the guidance of your instructor, raise the front of a vehicle off the ground, and set it on safety (jack) stands. Secure a dial indicator with the proper holding mechanisms so that the indicator’s plunger barely contacts the outside rim of one of the front wheels. With the plunger contacting the rim, set the dial to zero. Slowly rotate the wheel and watch the indicator. Any indicator needle movement indicates that there is some wheel distortion.

Answer Answers will vary.

CONCEPT ACTIVITY 5-5 Tools Take complete inventory of the tools in your toolbox or one assigned to you. Cross-reference the supplied tool list to the tools on hand.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 6: DIAGNOSTIC EQUIPMENT AND SPECIAL TOOLS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 6-1............................................................................................................ 6 CONCEPT ACTIVITY 6-2 ........................................................................................................... 7 CONCEPT ACTIVITY 6-3 ........................................................................................................... 8 CONCEPT ACTIVITY 6-4 ........................................................................................................... 9 CONCEPT ACTIVITY 6-5 .......................................................................................................... 10 CONCEPT ACTIVITY 6-6 .......................................................................................................... 11 CONCEPT ACTIVITY 6-7 .......................................................................................................... 12

SHORT ANSWER 1.

Explain why test lights are not recommended for testing computer circuits.

Answer Never use a 12V test light to diagnose components and wires in computer systems. The current draw of test light may damage the computer system components. Highimpedance test lights are available for diagnosing computer systems.

2. Name the two basic types of compression gauges.

Answer The two types of compression gauges are push-in and screw-in.

3. What tool is used to test engine manifold vacuum?

Answer A vacuum gauge is used to test engine manifold vacuum.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

4. Describe two methods of trapping asbestos/brake dust.

Answer Two methods of trapping brake dust include using a special vacuum system with HEPA filters and using a wet sink collection system.

5. Explain the purpose of a lab scope.

Answer A lab scope allows volts and amps to be displayed graphically over time.

6. Explain the difference between an internal and external spring compressor.

Answer An internal spring compressor fits inside of a coil spring and an external compressor fits around the outside of a coil spring.

7. Describe the differences between an on-car and off-car brake lathe.

Answer An on-car lathe attaches to the wheel hub and machines the rotor while it is mounted to the vehicle. An off-car lathe requires removing the rotor and machining it on a bench-top lathe.

MULTIPLE CHOICE 1.

Which of the following statements is not true? a. Exhaust analyzers allow a technician to look at the effectiveness of a vehicle’s emission control systems. b. Most exhaust analyzers measure HC in parts per million or grams per mile. c. CO is measured as a percent of the total exhaust. d. Emission controls greatly alter O2 and CO2 emissions.

Answer: d. Emission controls may have little effect on O2 and CO2 emission levels, and these two gases can be used to give a good look at the engine’s combustion process.

2. Technician A says that a brake drum micrometer has pointed anvils. Technician B says that a brake drum micrometer is a large inside micrometer that is read like any other micrometer. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

Answer: d. A brake disc micrometer has pointed anvils and is read the same way as other micrometers. A brake drum micrometer, however, has two flat surfaces on moveable arms and a dial indicator, and is read differently than other micrometers.

3. Technician A says that a pyrometer measures temperature. Technician B says that a thermometer measures temperature. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A pyrometer and a thermometer both measure temperature.

4. When using a voltmeter, Technician A connects it in series with the circuit being tested. Technician B connects the red lead of the voltmeter to the more positive side of the circuit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. Connect a voltmeter in parallel across the portion of the circuit being tested with the red lead on the most positive side of the circuit.

5. Technician A uses a digital volt/ohmmeter to test amperage. Technician B uses the same tool to test resistance. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A digital volt/ohmmeter may be used to test low amperage, voltage or resistance.

6. Technician A says that a charging station removes old refrigerant and recharges an A/C system. Technician B says that a charging station can remove, filter, and clean refrigerant. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A charging station can remove, evacuate, and recharge an A/C system.

Other equipment may be used to remove and recycle a system’s refrigerant. These machines draw the old refrigerant out of the system, filter it, separate the oil, remove moisture and air, and store the refrigerant for future use.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

7. Which of the following statements about manifold gauge sets is not true? a. An adapter is required for using R-12 gauges on an R-134a system. b. A manifold gauge set is used when discharging, charging, and evacuating and for diagnosing trouble in an A/C system. c. The gauge manifold is designed to control refrigerant flow. When the manifold test set is connected into the system, pressure is registered on both gauges at all times. d. R-134a service hoses have a black stripe along their length, the low-pressure hose is blue, and the high-pressure hose is red.

Answer: a. Separate gauge sets are required to service vehicles with different refrigerants.

8. When conducting an oil pressure test: Technician A says that lower than normal pressure can be caused by faulty piston oil rings. Technician B says that lower than normal oil pressure can be caused by excessive engine bearing clearances. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Lower than normal oil pressure can be caused by excessive engine bearing clearances.

9. Which of the following conditions can be revealed by fuel pressure readings? a. Faulty fuel pump b. Faulty fuel pressure regulator c. Restricted fuel delivery system d. All of the above Answer: d. All of these conditions may be revealed by fuel pressure readings.

10. Technician A uses a high-impedance test light on the high-voltage systems in hybrid vehicles. Technician B uses only CAT III test instruments to check high-voltage systems. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Only CAT-III test equipment should be used. High-impedance meters are used with computerized systems, not with high-voltage.

11. Technician A says that a sulfated and plugged fuel injector must be replaced.

Technician B says that a sulfated and plugged fuel injector can be cleaned. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Sulfated and plugged fuel injectors may be cleaned with fuel injector cleaners.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

12. The tests conducted by a scan tool can also be done by some ___. a. fuel injector pulse testers b. exhaust analyzers c. engine analyzers d. digital volt/ohmmeters Answer: c. Most engine analyzers contain a scan tool along with their other diagnostic tools.

13. When using a fuel injector pulse tester, Technician A says that little or no pressure drop indicates a plugged or defective injector. Technician B says that no pressure drop indicates an overly rich condition. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Little or no pressure drop can indicate a plugged or faulty injector. An excessive pressure drop indicates an overly rich condition.

14. To measure engine cranking current, a DMM (digital multimeter) can be used with a(n): a. continuity tester b. inductive pickup c. carbon pile d. tachometer Answer: c. An inductive pickup makes it easier to measure current in a circuit.

15. While discussing a clutch alignment tool, Technician A says that the part of the tool that fits into the clutch plate must have a slightly larger OD (outside diameter) than the bore in the disc. Technician B says that the OD of the part of the tool that goes into the pilot must be slightly smaller than the ID (inside diameter) of the pilot bushing. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The OD of the tool that goes into the pilot must be slightly smaller than the ID of the pilot bushing. And, the OD of the tool that holds the disc must be slightly smaller than the ID of the disc’s splined bore.

16. Technician A says that ball joints may be pressed into the control arm. Technician B says that control arm bushings are often pressed into the control arm. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

17. Which of the following is not a suitable way to bleed an entire hydraulic brake system? a. Manual bleeding b. Bench bleeding c. Pressure bleeding d. Vacuum bleeding Answer: b. Bench bleeding is done for bleed a master cylinder only, not the system.

18. Which is not a common use for a pressure transducer? a. Power-steering system pressure b. Oil pressure c. Engine vacuum d. Engine compression Answer: a. Pressure transducers can be used to check oil pressure, engine vacuum, and compression pressure. A special tester is required to properly test power steering system pressure.

TECH MANUAL CONCEPT ACTIVITY 6-1 General Hand Tools and Lab Equipment 1.

Does your lab provide a basic hand tool kit for students? ______________YES______________ NO Answer Answers will vary based on basic tools available and shop layout.

2. If yes, provide a brief description of the contents of the kit.

Answer Answers will vary based on basic tools available and shop layout.

3. If no, describe where and how student tools are kept and maintained.

Answer Answers will vary based on basic tools available and shop layout.

4. Does your lab have a tool room(s) for tool storage? ______________YES______________ NO Answer Answers will vary based on basic tools available and shop layout.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

5. If yes, describe what tools and equipment are kept in the tool room and how tools are checked in and out.

Answer Answers will vary based on basic tools available and shop layout.

6. If no, describe how specialty tools and pieces of equipment are kept and maintained.

Answer Answers will vary based on basic tools available and shop layout.

7. Locate and record the information for the lab equipment listed below: a. Hydraulic press make and model:

_______________________________________________ Rated output pressure:

________________________________________________________ Adjustable table height? ______________YES ______________NO b. Drill press make and model: ______________________________________________________ Chuck size capacity: ___________________________________________________________ Number of speeds: ___________________________________________________________ c. Floor jack lifting capacity: ______________________________________________________ d. List of available scan tools: ______________________________________________________ Answer Answers will vary based on basic tools available and shop layout.

CONCEPT ACTIVITY 6-2 Engine Diagnostic and Service Tools 1.

Determine if your lab has the following engine diagnostic and service tools. a. b. c. d. e. f. g. h.

Compressions tester ______________YES ______________NO Cylinder leakage tester ______________YES ______________NO Cooling system pressure tester ______________YES ______________NO Cooling system vacuum fill ______________YES ______________NO Combustion leak detector ______________YES ______________NO Valve spring compressors ______________YES ______________NO Cylinder bore gauges ______________YES ______________NO Dial indicators ______________YES ______________NO

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

i. j.

Piston ring installers ______________YES ______________NO Cam locking tools ______________YES ______________NO

Answer Answers will vary based on diagnostic and engine service tools available.

2. Which of the tools from the list above are diagnostic tools?

Answer Answers will vary based on diagnostic and engine service tools available.

3. Which of the tools from the list above are used for engine repair?

Answer Answers will vary based on diagnostic and engine service tools available.

CONCEPT ACTIVITY 6-3 Explore Training and Education Options 1.

Determine whether your lab has the following electrical diagnostic and service tools: a. b. c. d. e. f. g. h. i.

Digital multimeters ______________YES ______________NO Starter/Generator tester ______________YES ______________NO Battery tester ______________YES ______________NO Test lights ______________YES ______________NO Remote starter switch ______________YES ______________NO Terminal tool kit ______________YES ______________NO Lab scope ______________YES ______________NO Fused jumper wires ______________YES ______________NO Battery chargers ______________YES ______________NO

Answer Answers will vary.

2. List the brand(s) of digital multimeters available for student use.

Answer Answers will vary.

3. Identify the electrical safety categories for digital multimeters.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

4. Why is it important to use a digital multimeter with the correct electrical safety category rating?

Answer In the event of overload or improper use 5. Why is it important for jumper wires to be fused?

Answer To prevent damage to wiring and personal injury 6. Examine a battery charger and record the charging rates listed on the charger.

Answer Answers will vary.

7. List the steps to properly connect a battery charger to a battery.

Answer Ensure the charger is off, connect the positive lead, then the negative lead. Plug the charger in and set the charging rate.

8. List the safety information found on the battery charger.

Answer Answers will vary.

9. Why is it important to operate a battery charger by following all safety and charging rate guidelines?

Answer To prevent damage to the charger, the battery, and personal injury

CONCEPT ACTIVITY 6-4 Drivetrain Service Tools 1.

Determine whether your lab has the following drivetrain service tools: a. b. c. d. e.

Transmission/Transaxle jack ______________YES ______________NO Axle pullers ______________YES ______________NO Drive shaft angle gauge ______________YES ______________NO Coil spring compressor ______________YES ______________NO Wheel alignment equipment ______________YES ______________NO

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

f.

Wheel-bearing service tools ______________YES ______________NO

Answer Answers will vary.

2. Explain why a transmission/transaxle jack should always be used when removing and installing a transmission/transaxle.

Answer To prevent personal injury and damage to the vehicle 3. Describe why a drive shaft angle gauge is used.

Answer To check driveline angles associated with vibration concerns 4. Does your lab have internal and external coil spring compressors? ______________YES ______________NO Answer Answers will vary.

5. What type of suspension requires internal coil spring compressors?

Answer Answers will vary.

6. List the manufacturer and model of your alignment equipment.

Answer Answers will vary.

7. Describe the method used by the aligner to determine wheel position (example: laser, infrared).

Answer Answers will vary.

CONCEPT ACTIVITY 6-5 Brake System Tools 1.

Determine whether your lab has the following brake system service tools:

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

a. b. c. d. e. f. g.

Brake hydraulic pressure gauges ______________YES ______________NO Drum brake spring tools ______________YES ______________NO Asbestos reclamation equipment ______________YES ______________NO On-car brake lathe ______________YES ______________NO Off-car brake lathe ______________YES ______________NO Pressure brake bleeder ______________YES ______________NO Brake fluid testing equipment ______________YES ______________NO

Answer Answers will vary.

2. Describe the type of asbestos reclamation equipment available in your lab and how it is used.

Answer Answers will vary.

3. Explain why asbestos reclamation equipment is used when servicing brakes and clutches.

Answer To trap the asbestos fibers and prevent inhalation and long-term injury 4. Describe why an on-car brake lathe is used instead of an off-car lathe.

Answer To reduce runout and brake pulsation 5. Explain what other methods of brake bleeding are used instead of using a pressure bleeder.

Answer Manual bleeding, surge, and vacuum bleeding

CONCEPT ACTIVITY 6-6 HVAC Tools and Equipment 1.

Determine whether your lab has the following HVAC tools and equipment: a. b. c. d. e.

Refrigerant leak detector ______________YES ______________NO RRR station ______________YES ______________NO Thermometer ______________YES ______________NO Belt tension gauges ______________YES ______________NO Serpentine belt tools ______________YES ______________NO

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 6: Diagnostic Equipment and Special Tools

Answer Answers will vary.

2. Describe what type of refrigerant leak detector(s) are available in your lab.

Answer Answers will vary.

3. Explain why refrigerant reclamation and recycling equipment must be used for airconditioning service.

Answer By law, refrigerants must be reclaimed and recycled, not released into the atmosphere.

4. Describe the type of belt tension tools available in your lab.

Answer Answers will vary.

5. Explain the importance of accessory drive belts being properly tensioned.

Answer Excessive belt tension can damage bearings and cause rapid belt wear. Insufficient tension will allow the belt to slip, causing poor power steering and/or air-conditioning operation and reduced generator output.

CONCEPT ACTIVITY 6-7 Conclusions 1.

Based on your previous experiences with automotive repair facilities, how well do you think your lab is equipped compared to full-service repair shops?

Answer Answers will vary.

2. How well do you think your lab is equipped to handle the types of services and repairs you will be performing during your training?

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 7: WORKING SAFELY IN THE SHOP

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 6 Tech Manual ........................................................................................................................ 9 CONCEPT ACTIVITY 7-1 ............................................................................................................ 9 CONCEPT ACTIVITY 7-2 ........................................................................................................... 9 CONCEPT ACTIVITY 7-3 ........................................................................................................... 9 CONCEPT ACTIVITY 7-4 ........................................................................................................... 9 CONCEPT ACTIVITY 7-5 .......................................................................................................... 10 CONCEPT ACTIVITY 7-6 .......................................................................................................... 10

SHORT ANSWER 1.

What is the correct way to dispose of used oil filters?

Answer Used oil filters should be drained for at least 24 hours, then crushed and recycled.

2. Where in the shop should a list of emergency telephone numbers be posted?

Answer Up-to-date phone numbers for doctors, hospitals, and the fire and police departments should be clearly posted next to the phone.

3. Describe the correct process for lifting a heavy object.

Answer When lifting a heavy object: 1) Place your feet close to the object. Position your feet so you will be able to maintain a good balance.

2) Keep your back and elbows as straight as possible. Bend your knees until your hands reach the best place to get a strong grip on the object.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

3) Firmly grasp the object or container. Never try to change your grip as you move the load.

4) Keep the object close to your body, and lift it up by straightening your legs. Use your leg muscles, not your back muscles.

5) If you must change your direction of travel, never twist your body. Turn your whole body, including your feet.

6) When placing the object on a shelf or counter, do not bend forward. Place the edge of the load on the shelf and slide it forward.

7) When setting down a load, bend your knees and keep your back straight. Never bend forward.

4. What are bloodborne pathogens and why should technicians be concerned about them?

Answer Bloodborne pathogens are pathogenic microorganisms that are present in human blood and can cause disease. These pathogens include, but are not limited to, staph infections caused by the bacteria Staphylococcus aureus, hepatitis B virus (HBV), and human immunodeficiency virus (HIV).

5. List at least five things you should remember when using hand tools.

Answer The safety guidelines for using hand tools include the following: • Keep all hand tools grease-free.

• Your tools should also be inspected for cracks, broken parts, or other dangerous conditions before you use them.

• Hand tools should only be used for the purpose they were designed.

• Use the right tool for the job.

• Make sure the tool is of professional quality.

• Never use broken or damaged tools.

• When using a wrench, always pull it, not push it, toward you.

• Always use the correct size of wrench.

• Use a box-end or socket wrench whenever possible.

• Deep-well sockets should not be used when a regular size socket will work.

• Use an adjustable wrench only when it is absolutely necessary, pull the wrench so that the force of the pull is on the non-adjustable jaw.

• When using an air impact wrench, always use impact sockets.

• Never use wrenches or sockets that have cracks or breaks.

• Never use a wrench or pliers as a hammer.

• Never use pliers to loosen or tighten a nut, use the correct wrench.

• Always be sure to strike an object with the full face of the hammerhead.

• Always wear safety glasses when using a hammer and/or chisel.

• Never strike two hammer heads together.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

• • • • • •

Never use screwdrivers as chisels.

Be careful when using sharp or pointed tools.

Do not place sharp tools or other sharp objects into your pockets.

If a tool is supposed to be sharp, make sure it is sharp.

Knives, chisels, and scrapers must be used in a motion that will keep the point or blade moving away from your body.

Always hand a pointed or sharp tool to someone else with the handle toward the person you are handing the tool to.

6. List at least five precautions that must be adhered to while working with or around a vehicle’s battery.

Answer The general precautions for working with or around batteries are as listed below: • Make sure you are wearing safety glasses (preferably a face shield) and protective clothing when working around and with batteries.

• Keep all flames, sparks, and excessive heat away from the battery at all times, especially when it is being charged.

• Never smoke near the top of a battery and never use a lighter or match as a flashlight.

• Never lay metal tools or other objects on the battery.

• All batteries have an electrolyte, which is very corrosive. It can cause severe injuries if it comes in contact with your skin or eye.

• Lead-acid batteries use sulfuric acid as the electrolyte. Sulfuric acid is poisonous, highly corrosive, and produces gases that can explode in high heat.

• Acid from the battery damages a vehicle’s paint and metal surfaces and harms shop equipment.

• Allow the battery to cool before working with or around it. Also, never use or charge a battery that has frozen electrolyte.

• Always use a battery carrier or lifting strap to make moving and handling batteries easier and safer.

• Always charge a battery in well-ventilated areas.

• Never connect or disconnect charger leads when the charger is turned on.

• Never recharge the battery when the system is on.

• Turn off all accessories before charging the battery and correct any parasitic drain problems.

• Make sure the charger’s power switch is off when you are connecting or disconnecting the charger cables to the battery.

• Always double check the polarity of the battery charger’s connections before turning on the charger.

• Never attempt to use a charger as a boost to start the engine.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

7. Describe the correct procedure for connecting and disconnecting an air hose from an air tool.

Answer When connecting an air hose to an air tool, the below-mentioned steps must be followed: 1. Connect the tool to the air hose coupler by sliding the locking sleeve back and inserting the tool’s fitting into the hose coupler.

2. Turn on the air supply valve and listen for any leaks. Do not use the air hose if there is a leak from the hose or fittings.

3. When finished with the tool, turn the air supply valve off and press the trigger on the tool to bleed off the pressure in the hose.

4. Disconnect the tool and store the air hose properly.

8. Where can complete EPA lists of hazardous wastes be found?

Answer The Code of Federal Regulations contains a complete list of hazardous wastes.

9. There are many ways to clean parts while they are being serviced. These methods can be grouped into three separate categories. What are they?

Answer Cleaning automotive parts can be divided into three basic categories: chemical cleaning, thermal cleaning, and abrasive cleaning.

10. List at least five precautions that must be adhered to while working on a vehicle with a high-voltage system.

Answer Safety precautions that should always be adhered to when working on an electric drive vehicle are as follows: • Always adhere to the safety guidelines given by the vehicle’s manufacture.

• Obtain the necessary training before working on these vehicles.

• Be sure to perform each repair operation correctly.

• Disable or disconnect the high-voltage system before performing services to those systems. Do this according to the procedures given by the manufacturer.

• Anytime the engine is running in a hybrid vehicle, the generator is producing highvoltage and care must be taken to prevent being shocked.

• Before doing any service to an electric drive vehicle, make sure the power to the electric motor is disconnected or disabled.

• Systems may have a high voltage capacitor that must be discharged after the highvoltage system has been isolated. Make sure to wait the prescribed amount of time (normally about 10 minutes) before working on or around the high-voltage system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

• • • • • •

• • •

After removing a high-voltage cable, cover the terminal with vinyl electrical tape.

Always use insulated tools.

Use only the tools and test equipment specified by the manufacturer and follow the test procedures defined by the equipment manufacturer.

Alert other technicians that you are working on the high-voltage systems with a warning sign such as “high voltage work: do not touch.”

Always follow the instructions given by the manufacturer for removing high-voltage battery packs.

Wear insulating gloves, commonly called “lineman’s gloves,” when working on or around the high-voltage system. Make sure they have no tears, holes, or cracks and that they are dry. The integrity of the gloves should be checked before using them.

Always install the correct type of circuit protection device into a high-voltage circuit.

Many electric motors have a strong permanent magnet in them; individuals with a pacemaker should not handle these parts.

When an electric drive vehicle needs to be towed into the shop for repairs, make sure it is not towed on its drive wheels. Doing this will drive the generator(s), which can overcharge the batteries and cause them to explode. Always tow these vehicles with the drive wheels off the ground or move them on a flat bed.

11. What is the correct procedure for using a fire extinguisher to put out a fire?

Answer The proper procedure for using a fire extinguisher is the PASS system: 1) P, pull the pin.

2) A, aim at the base of the fire.

3) S, squeeze the handle.

4) S, sweep the entire width of the fire with the contents of the extinguisher.

12. Describe the proper operation of a vehicle when it is in the shop.

Answer Answers will vary but may include: Move vehicles very slowly in and out of the shop (2 mph maximum). When a vehicle is being brought in or taken out of the shop, do not get close to it or between the vehicle and the wall or a heavy object. Honk the vehicle’s horn and check carefully for people or other vehicles before driving out of the shop door. If an engine must be run in the shop, its exhaust must be collected by the shop’s ventilation system.

13. List six types of hazardous materials often found in the shop.

Answer Answers will vary but may include: waste oil, oil filters, batteries, metal residue, refrigerants, solvents, shop rags, and asbestos.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

14. Describe two ways to legally dispose of hazardous wastes.

Answer Some wastes can be recycled, such as coolant and refrigerant, and some wastes are hauled away and recycled or disposed of by a licensed hazardous waste disposal company.

15. What information is found in an SDS manual?

Answer The MSDS lists a product’s ingredients, potential health hazards, physical description, explosion and fire data, stability data, and protection data.

MULTIPLE CHOICE 1.

Which of the following offer(s) the least protection for your eyes? a. Face shield b. Safety glasses c. Splash goggles d. Prescription glasses Answer: d. Prescription glasses offer little protection unless they are made with polycarbonate lenses and are rated ANSI Z87 and have side shields fixed to the frame.

2. Which of the following statements about latex and nitrile gloves is not true? a. The gloves offer protection against cuts. b. The gloves offer protection against disease and grease buildup under and around your fingernails. c. Latex gloves are more comfortable but weaken when they are exposed to gas, oil, and solvents. d. Nitrile gloves are not as comfortable but they are not affected by gas, oil, and solvents.

Answer: a. Latex and nitrile gloves offer very little protection against cuts.

3. Which of the following statements about safety glasses is true? a. They should offer side protection. b. The lenses should be made of a shatterproof material. c. Some service operations require that additional eye protection be worn with safety glasses. d. All of the above statements are true.

Answer: d. All of these statements are true.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

4. Gasoline is ___. a. highly volatile b. highly flammable c. dangerous, especially in vapor form d. All of the above Answer: d. All of the statements are true.

5. Technician A says that it is recommended that you wear shoes with nonslip soles in the shop. Technician B says that steel-toed shoes offer the best foot protection. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Shoes worn in the shop should have nonslip soles, and steel-toed safety shoes are recommended.

6. Technician A says that used engine coolant should be collected and recycled.

Technician B says that all oil-based waste materials can be collected in the same container if an approved waste disposal company is hired to rid the shop of the oil.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Engine coolant should be collected and recycled. Petroleum-based fluids such as engine oil, transmission and power-steering fluids can be placed in the same container for recycling.

7. Federal Right-To-Know Laws concern ___. a. auto emission standards b. hazards associated with chemicals used in the workplace c. employee benefits d. hiring practices Answer: b. Right-to-know laws concern hazards associated with chemicals used in the workplace.

8. Which of the following is/are important when working in an automotive shop? a. Using the proper tool for the job b. Avoiding loose-fitting clothes c. Wearing steel-toed shoes d. All of the above Answer: d. All of the above

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

9. Technician A says that the flammability of a substance is a statement of how easily the substance vaporizes or explodes. Technician B says that the volatility of a substance is a statement of how well the substance supports combustion. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct.

10. Which of the following is not recommended for use when trying to extinguish flammable liquid fires? a. Foam b. Carbon dioxide c. Water d. Dry chemical Answer: c. Water is not recommended for extinguishing liquid fires; a class B fire extinguisher should be used.

11. Technician A ties his long hair behind his head while working in the shop. Technician B covers her long hair with a cap. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Long hair should be tied back or tucked under a cap.

12. Technician A uses compressed air to blow dirt from his clothes and hair. Technician B uses compressed air to clean off the top of a workbench. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Do not use compressed air for cleaning.

13. Heavy protective gloves should be worn when ___. a. welding b. grinding metal c. working with caustic cleaning solutions d. All of the above Answer: d. All of the above 14. Proper disposal of oil filters includes ___. a. recycling used filters b. burning them in the waste oil heater c. crushing them d. Both A and C Answer: d. Both a and c are correct.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

TECH MANUAL CONCEPT ACTIVITY 7-1 Shop Safety Map Make a simple line drawing of the shop. Then walk around the shop and identify all safety equipment. Mark the locations of the equipment on your drawing. Identify fire exits and evacuation routes, too.

Answer Answers will vary.

CONCEPT ACTIVITY 7-2 Shop Safety Inspection Perform an inspection of your lab checking for safety concerns, such as missing shields, damaged electrical cords, or other issues.

Answer Answers will vary.

CONCEPT ACTIVITY 7-3 Compressed Air 1.

Shop air pressure is regulated to 90 psi per OSHA regulations.

Answer Answers will vary.

2. Inspect the air hoses and fittings in the shop area. Note any leaks or other dangerous conditions that might exist.

Answer Answers will vary.

CONCEPT ACTIVITY 7-4 Fire Extinguishers Locate all of the fire extinguishers in the shop. Make a note of what types of fire each kind of extinguisher puts out.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 7: Working Safely in the Shop

CONCEPT ACTIVITY 7-5 Hazardous Waste Identify all storage areas for hazardous materials and wastes. Make sure they are properly labeled.

Answer Answers will vary.

CONCEPT ACTIVITY 7-6 SDS Locate the SDS or WHMIS manual in the shop. Look through the SDSs and read through the safety precautions for several commonly used fluids or chemicals.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 8: PREVENTIVE MAINTENANCE AND BASIC SERVICES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 8-1............................................................................................................ 7

SHORT ANSWER 1.

Describe the information found in a VIN. Answer The vehicle identification number (VIN) consists of 17 characters and numbers that contain the following information: country where the vehicle was manufactured, manufacturer, manufacturing division, body style, vehicle model, engine type, model year, and production sequence number.

2. List five different types of oil rating systems.

Answer The various oil rating systems are: • American Petroleum Institute (API) ratings • Energy-conserving ratings • Viscosity ratings • Society of Automotive Engineers (SAE) ratings • ILSAC Oil Ratings • ACEA Oil Ratings • Manufacturers’ Oil Ratings 3. Why should you wipe off the outside of a zerk fitting before injecting grease into it?

Answer Zerk fittings have a one-way spring-loaded check valve that allows grease into the joint but prevents it from leaking out. Dirt can plug the valve, allowing grease to leak out and water and dirt to leak in.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

4. List at least five things that should be checked while inspecting a vehicle’s battery.

Answer A battery inspection should include the following checks: • Inspecting the battery cover and case for dirt and grease.

• Checking the electrolyte level (if possible).

• Inspecting the battery for cracks, loose terminal posts, and other signs of damage.

• Checking for missing cell plug covers and caps.

• Inspecting all cables for broken or corroded wires, frayed insulation, or loose or damaged connectors.

• Checking battery terminals, cable connectors, metal parts, holddowns, and trays for corrosion damage or buildup — a bad connection can cause reduced current flow.

• Checking the heat shield for proper installation on vehicles so equipped.

5. How does a technician determine the proper inflation for a vehicle’s tires?

Answer The correct tire pressure is listed in the vehicle’s owner’s manual or on a decal (placard) stuck on one of the doorjambs, trunk lid, or fuel door.

6. Explain the purpose of a repair order and describe the type of information it should contain.

Answer Repair orders are legal documents that are used for many other purposes, such as payroll and general record keeping and contain information about the customer, the vehicle, the customer’s concern or request, an estimate of the cost for the services, and the time the services should be completed.

7. Why is preventive maintenance important to the life of the vehicle?

Answer Preventive maintenance can increase vehicle life by preventing excess wear and preventing bigger problems from arising.

8. Define preventive maintenance.

Answer Preventive maintenance is a service performed to reduce wear and extend component life by routinely inspecting and replacing certain items such as engine oil.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

MULTIPLE CHOICE 1.

Technician A stresses the need to follow the manufacturer’s recommendations for preventive maintenance to his customers. Technician B says that the proper PM service intervals depends on the customer’s driving habits and typical driving conditions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Follow manufacturer’s recommendations and also take vehicle usage and driving conditions into consideration.

2. Technician A says that the recommended tire inflation pressure is located on the tire sidewall. Technician B says that maximum tire cold inflation pressure is located on the sidewall. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The correct tire pressure is listed in the vehicle’s owner’s manual or on a decal (placard) stuck on the driver’s doorjamb. The air pressure rating on the tire is not the amount of pressure the tire should have. Rather this rating is the maximum pressure the tire should ever have when it is cold.

3. When working on a hybrid electric vehicle, which of the following statements does not reflect things you should be aware of? a. The engine will normally shut down and restart when as needed when stopped. b. The engine may start at any time when its control system senses that the battery needs to be recharged. c. The system may decide to power the vehicle, while it is parked, even if the engine is OFF. d. Make sure the “READY” lamp in the instrument cluster is off; this lets you know the system is off.

Answer: c. The system may decide to power the vehicle by electricity only and the engine is OFF. 4. While examining the color of an engine’s coolant: Technician A says that because it is orange, the cooling system should be flushed and new coolant put into the system.

Technician B says that if the coolant looks rusty, the cooling system should be flushed and new coolant put into the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

Answer: d. There are many colors of coolant in use and color alone is not an adequate method of determining the condition of the coolant.

5. While checking the condition of a vehicle’s ATF: Technician A says that if the fluid has a burnt color or odor, the fluid has been overheated. Technician B says that a milky color indicates that engine coolant has been leaking into the transmission’s cooler in the radiator. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians have identified a problem that required further diagnosis.

6. Technician A says that if a drive belt does not have the proper tension, it may produce squealing and chirping noises. Technician B says belt tension should be checked even if the engine has an automatic belt tensioner. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

7. Technician A says that to accurately check brake fluid level, the master cylinder cap must be removed. Technician B says not to remove the master cylinder cap unless absolutely necessary to stop air from entering the reservoir. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. On older vehicles, the master cylinder cap needed to be removed to check brake fluid level. Modern plastic reservoirs are translucent and allow the fluid level to be observed from the outside. Do not open the master cylinder reservoir unnecessarily as this allows air and moisture to contact the brake fluid.

8. Which of the following statements about drive belt slippage is not true? a. Excessive heat normally comes from slippage. b. As a V-belt slips, it begins to ride deeper in the pulley groove. c. Slippage can be caused by improper belt tension or oily conditions. d. When there is slippage, heat travels through the drive pulley and down the shaft to the support bearing of the component it is driving.

Answer: b. As a V-belt wears, it begins to ride deeper in the pulley groove. This is a normal occurrence, which is why periodic adjustment of belt tension is necessary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

9. Which of the following statements about an oil’s viscosity is not true? a. The ability of oil to resist flow is its viscosity. b. Viscosity is affected by temperature; hot oil flows faster than cold oil. Oil flow is important to the life of an engine. c. In the API system of oil viscosity classification, the lighter oils receive a higher number. d. Heavyweight oils are best suited for use in high-temperature regions. Low-weight oils work best in low-temperature operations.

Answer: c. SAE, not API, has established an oil viscosity classification system and this system assigns a numeric rating in which the higher viscosity, or heavier weight oils, receives the higher numbers.

10. While discussing a vehicle’s maintenance program: Technician A says most vehicles can safely follow the “normal” service schedule in the vehicle’s owner’s manual.

Technician B says common driving conditions often require a vehicle to use the “severe” maintenance schedule. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A typical PM schedule recommends particular service at mileage or time intervals. Driving habits and conditions should also be used to determine the frequency of PM service intervals. Most manufacturers also specify more frequent service intervals for vehicles that are used to tow a trailer or those that operate in extremely dusty or unusual conditions. It is important that your customer understands the differences between what the vehicle manufacturer considers normal and severe service. In many cases, if a vehicle is driven in any of the conditions listed in the severe service category, the maintenance intervals increase to twice as often as for normal service. Because operating conditions and manufacturer’s maintenance recommendations vary, many shops suggest using the manufacturer’s PM schedule as the minimum requirement.

11. Which of the following is not a true statement about a mechanic’s lien? a. This lien states that the shop may gain possession of the vehicle if the customer does not pay for the agreed-upon services. b. The right to impose a mechanic’s lien can be exercised by a shop within 30 days after the services have been completed. c. In most cases, the shop’s right to impose a lien on the vehicle being serviced must be acknowledged by the customer prior to beginning any services to the vehicle. d. This clause ensures that the shop will receive some compensation for the work performed, whether or not the customer pays the bill.

Answer: b. The right to impose a mechanic’s lien can only be exercised by a shop if the vehicle remains on the shop’s property for at least 90 days after the services have been completed.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

12. While discussing the effects of overtorquing wheel lugs: Technician A says that this can cause the threads of the lugs and/or studs to distort. Technician B says that this can cause disc brake rotor distortion. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

13. The most commonly used brake fluid in domestic vehicles is: a. DOT 2 b. DOT 3 c. DOT 4 d. DOT 5 Answer: b. Domestic automakers specify DOT 3, and import manufacturers are about equally divided between DOT 3 and DOT 4. There is no DOT 2 and very few applications call for DOT 5.

14. Which of the following greases are best suited for lubricating automotive wheel bearings? a. LA b. LB c. GA d. GC Answer: d. Wheel bearing lubricants have a prefix of “G” and GC has the highest performance ratings for wheel bearing lubrication and is the recommending wheel bearing lubricant.

15. While discussing the special preventive maintenance items for a hybrid vehicle: Technician A says that special coolants are required in most hybrids because the coolant not only cools the engine, but also the inverter assembly. Technician B says that the battery cooling system may have a filter in the ductwork from the outside of the vehicle to the battery box and that this filter needs to be periodically changed.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 8: Preventive Maintenance and Basic Services

TECH MANUAL CONCEPT ACTIVITY 8-1 Repair Orders Ask your instructor for a practice RO or use an electronic RO to create an order for a vehicle in the lab. You can have another student role-play the part of the customer. Record all of the necessary information and verify the information is for that particular vehicle.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 9: AUTOMOTIVE ENGINE DESIGNS AND DIAGNOSIS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 9-1............................................................................................................ 7 CONCEPT ACTIVITY 9-2 .......................................................................................................... 10 CONCEPT ACTIVITY 9-3 .......................................................................................................... 11 CONCEPT ACTIVITY 9-4 .......................................................................................................... 16 CONCEPT ACTIVITY 9-5 .......................................................................................................... 18

SHORT ANSWER 1.

What defines the combustion chamber of a four-stroke engine?

Answer The combustion chamber is the space between the top of the piston and the cylinder head. It is an enclosed area in which the gasoline and air mixture is burned.

2. Describe what takes place during the four strokes of a four-stroke cycle engine.

Answer The four strokes are intake, compression, power, and exhaust. During the intake stroke, the air/fuel mixture is drawn into the cylinder. The mixture is them compressed during the compression stroke to prepare it for combustion. During the power stroke, the compressed air and fuel is ignited and the resultant increase in pressure forces the piston down with great force. Once the piston has moved down in its bore, the spent gases from combustion are pushed out of the cylinder.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

3. As an engine’s compression ratio increases, what should happen to the octane rating of the gasoline?

Answer As an engine’s compression ratio increases, there should also be an increase in the octane rating of the fuel in order to avoid abnormal combustion. Gasoline with too low an octane rating may ignite before spark occurs due to the additional heat produced by a higher compression ratio, or it may burn in an explosive and destructive manner.

4. What test can be performed to check the efficiency of individual cylinders?

Answer A cylinder balance test can be used to compare the efficiency of each cylinder. Ideally, all of the cylinders should produce an equal amount of power.

5. Describe five ways in which an engine can be classified.

Answer Engines may be classified by their operational cycle, number of cylinders, cylinder arrangement, valve train type, ignition type, cooling system, and fuel type.

6. In a four-cylinder engine with a firing order of 1–3–4–2, what stroke is piston #4 on when #1 is on its compression stroke?

Answer In four-stroke cycle engines, the order of the strokes is intake, compression, power, and exhaust. In the engine, mentioned in the question, when cylinder #1 is on the compression stroke, cylinder #3 will be on its power stroke, cylinder #4 will be on the exhaust stroke, and cylinder #2 will on the intake. Therefore, when cylinder #1 is on its compression stroke, cylinder #4 will be on its exhaust stroke.

7. What engine components are tested by the cranking compression test?

Answer The cylinder head, the head gasket, the piston rings, the valves 8. Explain what could cause lower-than-normal engine vacuum readings.

Answer Incorrect valve timing, restricted intake, worn piston rings, vacuum leaks

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

9. Bubbles are seen in the radiator when performing a cylinder leakage test. Describe two possible causes.

Answer Cracked cylinder head or block and a leaking head gasket 10. List four factors regarding how much air can be drawn into an engine.

Answer The size of the throttle body, the size of the intake valves, the piston stroke, the engine speed 11. List four causes of low oil pressure.

Answer Worn oil pump, restricted oil pick up, worn main bearings, and worn rod bearings

MULTIPLE CHOICE 1.

Which of the following statements about engines is not true? a. The engine provides the rotating power to drive the wheels through the transmission and driving axle. b. Only gasoline engines are classified as internal combustion. c. The combustion chamber is the space between the top of the piston and the cylinder head. d. For the combustion in the cylinder to take place completely and efficiently, air and fuel must be combined in the right proportions.

Answer: b. Both gasoline and diesel engines are internal combustion engines.

2. Which stroke in the four-stroke cycle begins as the piston reaches BDC after combustion takes place? a. Power stroke b. Exhaust stroke c. Intake stroke d. Compression stroke Answer: b. The exhaust stroke begins after combustion to push the spent gases out of the cylinder.

3. Which of the following is not a true statement about diesel engines? a. The operation and main components of a diesel engine are comparable to those of a gasoline engine. b. Diesel and gasoline engines are available as four-stroke combustion cycle engines.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

c. Diesel engines rely on glow plugs instead of spark plugs to initiate ignition. d. The compression ratio of diesel engines is typically three times that of a gasoline engine.

Answer: c. Ignition begins when diesel fuel is sprayed into the hot compressed air in the cylinder. Glow plugs are used to warm the intake air when the temperature is low.

4. Technician A says head gasket thickness has an effect on compression ratio.

Technician B says connecting rod length has an effect on compression ratio. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both the thickness of the head gasket and the length of the connecting rod will have an effect on the compression ratio of the engine.

5. The stroke of an engine is the ___ crank throw. a. half b. twice c. four times d. equal to Answer: b. The stroke of an engine is twice the crankshaft throw.

6. Which of the following is an expression of how much of the heat formed during the combustion process is available as power from the engine? a. Mechanical efficiency b. Engine efficiency c. Volumetric efficiency d. Thermal efficiency Answer: d. Thermal efficiency describes how well the engine converts the heat produced during combustion into usable power.

ASE-STYLE REVIEW QUESTIONS 1.

While diagnosing the cause for blue smoke from the tailpipe of a gasoline engine: Technician A says that a faulty fuel injection system is a likely cause. Technician B says that it is most likely caused by coolant leaking into the combustion chamber.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Blue exhaust is typically caused by oil in the combustion chamber. A coolant or water leak would be evident by a whitish exhaust.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

2. While discussing piston slap: Technician A says that it is a high-pitched clicking that becomes louder during deceleration caused by detonation. Technician B says that it is the noise made by the piston when it contacts the cylinder wall due to excessive clearances. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Piston slap is a hollow, bell-like noise that is produced when the piston slaps against the cylinder wall due to excessive clearances. It is commonly heard when the engine is cold, and gets louder when the engine is accelerated. Detonation causes a knocking sound.

3. While determining the cause for air leaking out of the oil throttle body during a cylinder leakage test: Technician A says that a burnt intake valve is indicated. Technician B says that a warped cylinder head or bad head gasket is indicated. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Air leaking from the throttle body normally means the intake valves are not sealing properly. A warped cylinder head or bad head gasket would allow air to escape through other cylinders or through the cylinders’ sealing surfaces.

4. While diagnosing the cause for an engine having good results from a compression test and cylinder leakage test but poor results from a cylinder power balance test: Technician A says that incorrect valve timing is the most likely cause. Technician B says that a severely worn cam lobe is a likely cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A worn cam lobe would most likely not show up on either a compression or a cylinder leakage test, but would cause the cylinder to produce less power than other cylinders. Incorrect valve timing would affect all cylinders, therefore the cylinder power balance test would not give poor readings.

5. While looking at the results of an oil pressure test: Technician A says that higher than normal readings can be caused by using an incorrect viscosity oil. Technician B says that higher than normal readings can be expected on a cold engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

Answer: c. Both technicians are correct. High viscosity oil can cause high oil pressure.

When an engine is cold, the oil pressure will be higher due to the viscosity of the oil.

6. A vehicle is producing a sharp, metallic rapping sound originating in the upper portion of the engine. It is most noticeable during idle. Technician A diagnoses the problem as piston pin knock. Technician B says that the problem is most likely a loose crankshaft thrust bearing. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A sharp metallic rapping sound originating from the upper portion of an engine would most likely be a piston pin knock. A damaged or worn crankshaft thrust bearing would result in a dull steady knock originating near the bottom of the engine.

7. While conducting an engine vacuum test: Technician A says that a steady low vacuum reading can be caused by a burned intake valve. Technician B says that an overall low vacuum reading is caused by something that affects all of the engine’s cylinders. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A burned intake valve would cause a fluctuating needle on the gauge.

8. While determining the most likely problem of an engine with poor compression test results but acceptable cylinder leakage readings: Technician A says that the problem may be incorrect valve timing. Technician B says that the problem is worn valve seats.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. B is wrong because worn valve seats would cause poor compression and cylinder leakage test results.

9. When a customer states that black exhaust smoke is coming from the exhaust: Technician A says faulty oil rings may be the cause. Technician B says a faulty head gasket may be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Black exhaust smoke is normally indicative of a very rich air/fuel mixture or incomplete combustion. Faulty oil rings would cause blue exhaust, and a bad head gasket or warped cylinder head would cause a whitish smoke.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

10. Technician A says that if an engine had good results from a compression test, it will have good results from a cylinder leakage test. Technician B says that if an engine had good results from a cylinder leakage test, it will have good results from a running compression test. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Because a compression test is performed while cranking the engine and a cylinder leakage test is performed while the crankshaft is stationary, the results of the two tests do not indicate how sound the engine is while it is running.

TECH MANUAL CONCEPT ACTIVITY 9-1 Air Pressure Air pressure, or atmospheric pressure, is a measurement of the weight of the air from the edge of the atmosphere down to ground level. We do not often think about the air that surrounds us, but the weight of that air has a huge impact on our lives. Air pressure at sea level is about 14.7 pounds per square inch (psi). This means that if we could take a 1-squareinch column of air from the ground up to the edge of space, it would have a weight of approximately 14.7 pounds (Figure 9-1). As you move higher and higher above sea level, air pressure decreases.

1.

Explain why air pressure decreases with altitude.

Because air pressure is a product of our atmosphere, it is subject to changes in the atmosphere. In addition, because air pressure is affected by the weather, it can be easily measured and recorded in your lab on a daily basis by making this simple barometer. Take a glass container and stretch a balloon or similar material over the opening of the jar. If necessary, use a rubber band to seal the balloon around the jar: it must be airtight. Next, attach a straw horizontally to the balloon with a piece of tape.

The height of the end of the straw can be marked on a piece of paper to record the changes in air pressure (Figure 9-2). As the local air pressure changes, the straw will rise or drop with the pressure changes. Record the height over several days or weeks to track the changes in air pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

FIGURE 9–1 A column of air 1 square inch extending from the earth’s surface at sea level to the outer edge of the atmosphere weighs 14.7 pounds.

FIGURE 9–2 Measuring local barometric pressure with self-made barometer.

Answer There is less atmosphere above as elevation increases.

2. Describe how this simple barometer operates.

Answer Air pressure changes above the barrier, forcing it down or allowing it to rise.

3. What causes the up or down movement of the straw?

Answer Changes in air pressure causes this.

4. If the air in the jar were heated or cooled, how would the straw react?

Answer The straw will move up and down as the air is cooled or heated.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

5. How does temperature affect the pressure inside the jar?

Answer Increasing temperature will increase the pressure, decreasing the temperature will decrease the pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

CONCEPT ACTIVITY 9-2 Pressure and Temperature We saw in the last activity that the air pressure changes, but what can cause the pressure to change? Temperature is one factor that can cause pressure change. When air is heated, it rises, and when air is cooled, it falls. The reason for this is that as air is heated, it weighs less per unit of volume than cooled air. Because the hotter air is less dense, the cooler denser air lifts it. To demonstrate how temperature affects pressure, fill a plastic milk jug approximately one-third of the way full with very hot water. Use caution when working with hot water, to avoid being accidentally burned. Screw the cap on securely and wait about an hour.

1.

What happened to the jug?

Answer The jug collapsed slightly.

2. Why did the jug react the way it did?

Answer The air pressure inside decreased.

3. How did the outside air pressure affect the jug?

Answer The pressure pushed against the outside of the jug.

To see how increasing air temperature will result in increased air pressure, place a balloon over the opening of a plastic water bottle that is filled about halfway. Carefully heat the water bottle with a heat gun, hair dryer, or other safe and instructor-approved method.

4. Describe what happened to the balloon.

Answer It may expand slightly.

5. Why did the balloon react the way it did?

Answer The pressure in it increased with temperature.

6. What does the balloon do as the water and bottle slowly cool?

Answer It contracts.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

7. Why did this happen?

Answer The pressure in it equalized with temperature.

CONCEPT ACTIVITY 9-3 Pressure and Volume The pressure of air (or other gas) in a container can be affected by several things, such as the temperature in the container and the volume of the container. In an automotive engine, air and fuel are drawn into the cylinder. As the piston moves up in the cylinder, the volume becomes smaller. This decrease in volume causes the pressure and temperature of the gas to increase as the molecules are forced more tightly together.

When the volume of the cylinder is increased, such as when the piston moves from top dead center (TDC) to bottom dead center (BDC) on the intake stroke, the pressure in the cylinder decreases.

1.

Why does the pressure decrease?

Answer The piston moving downward increases the volume of the cylinder.

2. What causes the air to enter the cylinder?

Answer Outside of the engine there is atmospheric pressure, in the cylinder the pressure is reduced, since pressure moves from high to low, the higher pressure forces the air into the cylinder.

Place the small open end of a syringe against one of your fingers and draw the plunger out until it stops moving.

3. Describe what happened.

Answer Answers will vary but may include observations such as there was suction inside the syringe.

4. What was the effect within the syringe by pulling out on the plunger?

Answer There was decreased pressure inside the syringe.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

Attach a pressure/vacuum gauge to a syringe with the plunger about halfway pulled out. Pull the plunger back to the end of its travel and note the reading on the gauge.

5. Gauge reading: Answer Answers will vary but may include the reason that pressure decreased.

6. With the plunger at the end of its travel, push the plunger in, and note the reading on the gauge.

Answer Answers will vary but may be 10 in Hg. Obtain two syringes of equal size and pull each plunger out about halfway. Then connect the two together with a piece of vacuum hose.

7. Push on one plunger and note what happens to the other plunger.

Answer Answers will vary but may include options such as the other plunger moves outward.

8. Was the result what you expected? Why or why not?

Answer Answers will vary but may include yes or no.

9. What caused the movement of the second plunger?

Answer Answers will vary but may include causes such as increased pressure in the system.

10. Now, pull on the plunger and note what happens.

Answer Answers will vary but may include observations such as the plunger moves inward.

11. Why did the second plunger move?

Answer Answers will vary but may include reasons such as decreased pressure in the system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

12. How did the change in pressure in the first syringe affect the second syringe?

Answer Answers will vary but may include options such as equally.

Obtain from your instructor a vacuum pump and a cone-shaped dispensing lid from a differential fluid bottle. Attach the cap to an empty motor oil quart bottle. Pull vacuum on the bottle via the cap and watch the oil bottle.

13. What happened to the oil bottle?

Answer Answers will vary but may include results such as the bottle collapses.

14. Why did the bottle react the way it did?

Answer Answers will vary but may include reasons such as there was decreased pressure inside the bottle.

15. Release the vacuum and note the effect on the bottle. Explain the result.

Answer Answers will vary but may include observations such as the bottle expands back outward some.

Using a vacuum pump and a vacuum chamber connected to a bottle of oil, apply vacuum and watch the oil.

16. Why did the oil move from the oil bottle?

Answer Answers will vary but may include reasons such as there was decreased pressure in the system.

You have now demonstrated a basic physical principle that a substance tends to move from a higher pressure to a lower pressure.

Next, place a balloon into an empty water bottle, and leave the balloon opening above the opening of the bottle. Now attempt to inflate a balloon that is inside of the bottle.

17. Explain what happened.

Answer Answers will vary but may include observations such as the balloon does not inflate greater than the volume of the bottle.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

18. Why did the balloon not inflate normally?

Answer Answers will vary but may include reasons such as it is confined by the bottle.

19. What could be done to allow the balloon to properly inflate?

Answer Answers will vary but may include options such as removing it from the bottle The balloon was trying to inflate within the bottle and was exerting pressure against the air already inside the bottle. Because the air in the bottle had nowhere to go, the pressure equalized against the pressure you attempted to place in the balloon, causing a pressure balance. The harder you attempted to blow up the balloon, the more the pressure in the bottle worked against you. Now place a small hole in the bottom of the bottle and repeat the experiment.

20. Describe what happened.

Answer Answers will vary but may include options such as the balloon may inflate through the hole.

21. Why was the balloon able to inflate more than before?

Answer Answers will vary but may include reasons such as a larger opening allowed expansion.

22. If you plug the hole in the bottle and release the air from the balloon, what will happen to the bottle?

Answer Answers will vary but may include responses such as it may collapse.

23. Why? Answer Answers will vary but may include reasons such as reduced pressure.

You have seen how pressure can move from high to low and how to increase pressure.

Next, we will examine low pressure, also called vacuum. Vacuum is pressure that is less than atmospheric pressure. Pressure can be measured with a pressure gauge, such as a tire pressure gauge, but a tire gauge is calibrated to read atmospheric © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

pressure as zero. This is referred to as psi gauge, or psig. A flat tire will read zero psi on a pressure gauge, but it actually has 14.7 psi (or equivalent local) pressure (Figure 9-3). To read pressures lower than atmospheric, you will need either a gauge that reads psi absolute (psia) or a vacuum gauge. Using a vacuum gauge and a pressure chart, you can easily see what a vacuum-gauge reading reflects in actual air pressure.

Connect a vacuum gauge to a vacuum hose and start the engine.

FIGURE 9–3 Relationship between atmospheric pressure, higher pressure, and vacuum.

24. Record the gauge reading.

Answer Answers will vary but may include readings in the range 17–22 in Hg. 25. What does this equate to in actual air pressure?

Answer Answers will vary but may include readings in the range 8–4 psi.

26. Why is the engine producing vacuum?

Answer Answers will vary but may include reasons such as the movement of the pistons in the cylinders.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

27. What does the vacuum gauge read if the engine speed is increased?

Answer Answers will vary but may include responses such as slightly less than more.

CONCEPT ACTIVITY 9-4 Displacement Engine size is determined by cylinder displacement, which is the total volume of the cylinders and combustion chambers. To understand displacement, let us first look at the volume of a basic cylinder. When the piston is at bottom dead center, the cylinder can hold a certain amount of liquid: let us call the amount V for the moment. To determine the value of V, we need to know a few things, such as the radius of the cylinder and its depth. Radius is one-half of the diameter, which is the distance across the cylinder from side to side. Depth is the total height from the top edge to the bottom of the cylinder, which is also the top of the piston (Figure 9-4).

FIGURE 9–4 Measuring a cylinder.

Suppose we have a cylinder that is 3.5” in diameter and 3.5” deep; this would equal a bore of 3.5” and a stroke of 3.5”. Bore and stroke are the terms used to describe cylinder diameter and depth. To calculate the volume, the bore of 3.5” is converted to radius. Because radius is half of diameter (or bore), then a bore of 3.5” has a radius of 1.75”. Using the formula V = πr2h, where V is the total volume; π is the value of pi, or 3.14159; r2 is the cylinder radius squared; and h is the height (or stroke) of the cylinder, the volume can be determined. Our equation will look like V = 3.14159 x 1.752 x 3.5. The cylinder volume, or displacement, equals about 33.67 cubic inches, or 33.73”. If our engine is an eight-cylinder one, then we multiply 8 x 33.73” to get a total engine displacement of 269.6 cubic inches.

To calculate displacement using cubic centimeters (cc), simply use the same formula but substitute the metric equivalent measurements for the English ones. In our sample engine, we had a bore and stroke of 3.5 inches each. Because there are 2.54 centimeters (or 25.4 millimeters) per inch, simply convert inches to centimeters by multiplying 3.5 b y 2.54. This gives us a cylinder bore and stroke measurement of 8.89 centimeters. Now substitute 8.89

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

into our equation, 3.14159 x 8.89 cc2 x 8.89 x 8 for a displacement of 4,412 cc, or 4.4 liters. A nice benefit of using metric units is that conversion is a matter of just moving the decimal.

Another method of calculating displacement is by using the formula 0.785 x Bore x Stroke x Number of cylinders. Because 0.785 is roughly one-quarter of π, some people find it easier to remember this way because the actual bore measurement can be used.

To measure displacement, obtain from your instructor a cylindrical container that you can measure for the diameter and depth. Using a telescoping gauge and depth gauge, measure the inside diameter and depth of the container, and record your measurements. Calculate the volume of the container using the formulas above.

1.

Inside diameter______________ Depth ______________ Volume ______________ Answer Answers will vary but may include readings such as 3.5” x 3.5”, 33.7 cubic inches.

Using the volume you found, multiply the total by 4, 6, and 8 to get an idea of what the amount equates to for a four-cylinder, six-cylinder, and eight-cylinder engine.

2. Four-cylinder ______________Six-cylinder ______________Eight-cylinder______________ Answer Answers will vary.

Compare these numbers with the engine sizes found in modern cars and light trucks.

3. How does the displacement compare to the external size of an engine?

Answer Larger cylinder displacement will increase the external size of the engine.

4. What are some factors that limit engine displacement?

Answer Overall engine size, engine compartment limitations, crankshaft stroke, piston size 5. Can engine wear affect displacement? Why/how?

Answer Yes, cylinder wear increases cylinder bore size.

6. If an engine is bored oversize to correct for cylinder wear, what effect will this have on displacement?

Answer This would increase displacement.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

7. How would carbon buildup on a piston affect displacement?

Answer It would reduce displacement.

CONCEPT ACTIVITY 9-5 Compression Ratio Using cylinder displacement, the measure of bore and stroke, cylinder compression ratio can be determined. Compression ratio refers to the volume of the cylinder when the piston is at BDC compared to the volume when the piston is at TDC. The difference in volume is the compression ratio. Suppose we have a clear cylinder, such as a syringe that holds 100 cc of liquid and has graduated markings along the length, marking every 10 cc (Figure 9-5). Pull the plunger back, filling the syringe with 100 cc of air. This is similar to filling the cylinder of an engine when the piston has moved from TDC to BDC on the intake stroke. Now, cap the opening of the syringe and push the plunger back in, compressing the trapped air inside.

Notice that as you compress the air, it becomes more difficult to push the plunger. If you can compress the original 100 cc volume of air until the plunger reaches the 10-cc mark, you have compressed the air by a factor of 10, or by a ratio of 10:1. By taking the original volume of 100 cc and reducing it down to 10 cc, you have compressed the air 10 times. Compression ratio = volume 1/volume 2 or 100/10 = 10 or 10:1.

FIGURE 9–5 A typical 100 cc syringe.

1.

Why did the plunger become harder to push as the volume of air decreased?

Answer The pressure increased as the volume decreased.

2. What would the compression ratio in the syringe be if you compressed the air from 100 cc to 50 cc?

Answer 2:1 3. If you compressed the air in the syringe to the 20-cc mark, what would the compression ratio be?

Answer 5:1

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 9: Automotive Engine Designs and Diagnosis

For a simple experiment, Boyle’s Law can be used to determine the pressure in the syringe. P = pressure; Pi = initial pressure, or 14.7 psi, or atmospheric pressure at sea level; Vi is the initial volume, in this case 100 cc; and Vf is the final volume. Use the formula for final pressure or Pf = PiVi /Vf and a compression ratio of 2:1 (100 cc to 50 cc): 4. What would be the air pressure in the syringe?

Answer 29.4 psi 5. If the air were compressed 10:1, what would the pressure of the air in the syringe be?

Answer 147 psi 6. What design factors affect the compression ratio of an engine?

Answer Piston type, combustion chamber size, crankshaft stroke 7. Why do some engines have higher or lower compression ratios than others?

Answer Different power demands, octane demands, use of turbo or superchargers 8. Why is the compression ratio of a gasoline-powered engine different from a diesel engine?

Answer Diesel engine compresses the air so much that when fuel is injected into the cylinder it ignites.

The actual pressure in an operating cylinder will be different than what you have experienced with this experiment because of the effects of valve timing, intake design, combustion chamber design, and other factors. These experiments do not take into account combustion chamber size, which also has an effect on displacement and compression ratio.

By completing these activities and experiments, you should have an understanding of some of the basic principles that govern engine operation. The following job sheets apply your understanding of these principles.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 10: ENGINE DISASSEMBLY AND CLEANING

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 10-1 .......................................................................................................... 7 CONCEPT ACTIVITY 10-2 ......................................................................................................... 7

SHORT ANSWER 1.

What should be worn when working with any type of cleaning solvent or chemical?

Answer Wear protective gloves and eye protection when using chemical cleaners.

2. List five different methods of cleaning engine components.

Answer Chemical cleaners, thermal cleaners, abrasive cleaners, vibratory cleaners, ultrasonic cleaners 3. Why should a memory saver be installed before disconnecting a vehicle’s battery?

Answer This will prevent the vehicle’s computers and other devices from losing what they have stored in their memory.

4. What should be done before removing the vacuum and electrical wiring?

Answer Label or take pictures of connections for reassembly.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

5. Why is it important to loosen the cylinder head bolts in the recommended order?

Answer To reduce and prevent cylinder head warp 6. If the service information does not provide a loosening sequence for the cylinder head bolts, what should you do?

Answer Loosen in reverse of the tightening sequence 7. Why must a cylinder ridge be removed before attempting to remove the piston?

Answer To prevent damage to the ring lands of the piston

MULTIPLE CHOICE 1.

What is the best way to lift a vehicle when preparing to remove an engine? a. Frame contact hoist b. Drive on lift c. Hydraulic jack and safety stands d. Engine hoist Answer: a. When removing an engine, setting the vehicle on a frame contact hoist is recommended.

2. Which of the following statements is not true? a. When the engine is removed through the bottom of the vehicle, use an engine cradle and dolly to support the engine. b. If the manufacturer recommends engine removal through the hood opening, use an engine hoist. c. Regardless of the method of removal, the engine and transaxle in a FWD vehicle are usually removed as a unit. d. When removing an engine from a RWD vehicle, suspension disassembly is often required.

Answer: d. To remove an engine from a RWD vehicle does not require the removal or disassembly of the suspension.

3. The buildup of minerals and deposits inside the cooling system is called ___. a. organic soil b. scale c. rust d. grime Answer: b. The buildup of minerals and deposits is called scale. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

4. Hydrocarbon solvents are ___. a. flammable b. toxic c. both a and b d. neither a nor b Answer: c. Hydrocarbon-based solvents are both toxic and flammable.

5. Which cleaning method uses high-frequency sound waves to create microscopic bubbles that loosen dirt from parts? a. Ultrasonic b. Salt bath c. Thermal d. Caustic Answer: a. Ultrasonic cleaning uses high-frequency sound waves to loosen dirt particles.

6. Parts must be ___ when they go into an abrasive blast machine. a. wet b. dry c. grease-free d. both b and c Answer: d. Parts must be dry and grease-free before abrasive cleaning for best results.

7. An engine block should be mounted to an engine stand using a minimum of ___ bolts. a. four b. six c. three d. five Answer: a. Use at least four bolts to mount an engine block to an engine stand.

8. Which of the following is not considered part of the organic soil grouping? a. Petroleum by-products derived from crude oil, including tar, road oil, engine oil, gasoline, diesel fuel, grease, and engine oil additives b. Rust that is a product of coolant and aluminum c. By-products of combustion, including carbon, varnish, gum, and sludge d. Coatings, including such items as rust-proofing materials, gasket sealers and cements, paints, waxes, and sound-deadener coatings Answer: b. Rust is not an organic soil; it is the result of a chemical reaction that takes place when iron and steel are exposed to oxygen and moisture. Corrosion, like rust, results from a similar chemical reaction between oxygen and metal containing aluminum.

If left unchecked, both rust and corrosion can physically destroy metal parts quite rapidly. In addition to metal destruction, rust also acts to insulate and prevent proper heat transfer inside the cooling system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

9. Which of the following statements is not true about thermal cleaning? a. The main advantage of thermal cleaning is a total reduction of all oils and grease on and in blocks, heads, and other parts. b. After a part has been thermally cleaned, it should be submerged in water to cool it quickly. c. Thermal cleaning leaves behind a dry, powdery ash on the parts. d. After a part has been thermally cleaned, it should be washed or blasted with shot.

Answer: b. A slow cooling rate is recommended to prevent distortion that could be caused by unequal cooling rates within complex castings.

10. Which of the following is not a common way to identify the location of cracks in the engine block or cylinder head? a. Pressure checks b. Vacuum test c. Magnetic particle inspection d. Penetrant dye Answer: b. A vacuum test is used to determine if a physical problem exists within an engine but cannot be used to find cracks in components.

ASE-STYLE REVIEW QUESTIONS 1.

While working on an engine with an excessive amount of sludge buildup: Technician A says that the presence of sludge is a signal to look for wear on other components.

Technician B says that excessive buildup can indicate a poor maintenance schedule.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct.

2. While discussing the common causes for cracks developing in a cylinder block or head: Technician A says that the chilling of a hot engine by a sudden rush of cold water or air over the surface may cause cracking. Technician B says that excessive overheating is a common cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

3. Technician A uses a crane to remove an engine from its compartment. Technician B uses an engine cradle to remove an engine from its compartment. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A crane is used on RWD vehicles and the engine cradle is used on some FWD vehicles.

4. While removing a cylinder head: Technician A keeps all rocker arms and pushrods in order. Technician B loosens each head bolt, starting with the center bolts and moving toward the ends. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. The pushrods and rocker arms should be kept in order to aid in diagnosing valve-related problems. The cylinder head bolts should be loosened one or two turns beginning at the ends and working toward the center or according to the order specified by the manufacturer.

5. While discussing abrasive cleaners: Technician A says that the shot is angular in shape and is used for aggressive cleaning. Technician B says that grit is an angular-shaped media and is used to peen metal surfaces. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Of the two types of abrasive media, shot is round and is used for surface peening, and grit is angular and used for aggressive cleaning jobs.

6. Technician A labels or marks all electrical wires before disconnecting them. Technician B labels or marks all vacuum hoses and verifies the connections to the underhood decal before disconnecting them. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct 7. While discussing cleaning engine parts: Technician A says that the cleaning method used depends on the component to be cleaned and the type of cleaning equipment available. Technician B says a parts tumbler is good for cleaning aluminum components such as intake manifolds and cylinder heads. Who is correct? a. Technician A b. Technician B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

c. Both A and B d. Neither A nor B Answer: a. The choice of cleaning methods depends on the component to be cleaned and the available cleaning equipment. A parts tumbler can save considerable labor when cleaning small parts such as engine valves is a tumbler. Various cleaning media can be used in a tumbler to scrub the parts. A parts tumbler is normally not used to clean aluminum or large parts.

8. While loosening the axle shaft hub nuts on a FWD vehicle: Technician A says that a large breaker bar should be used to prevent damage to the bearings. Technician B says that these nuts should be loosened with the vehicle on the floor and the brakes applied. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct.

9. While preparing to remove an engine: Technician A turns the crankshaft pulley to set the engine at number 1 cylinder TDC. Technician B removes the drive belt and crankshaft pulley. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. While preparing to remove an engine from a vehicle, there are many things that should be removed or disconnected. Most of the items connected to the engine are easier to remove once the engine is out, therefore only those items that may interfere with engine removal should be moved or removed before engine removal. An example of this is the drive belts. After a drive belt is removed, the drive pulleys do not need to be removed unless they will be in the way during engine removal. Also, while removing the drive belts there is no need to worry about the position of the engine’s crankshaft. Again, you can set this (if necessary) much easier once the engine is out of the vehicle.

10. After removing the vehicle’s hood in preparation for removing the engine: Technician A places the hood on the roof of the vehicle. Technician B sets the hood aside in a safe place on fender covers or cardboard. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct; however, A is correct only if he/she also does what B does.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 10: Engine Disassembly and Cleaning

TECH MANUAL CONCEPT ACTIVITY 10-1 Service Procedures Choose two vehicles, each made by a different manufacturer, and compare the engine disassembly procedures given in the service information. Describe the similarities and the differences, and explain why there are differences.

Answer Answers will vary but may include content from service information regarding engine disassembly procedures. Difference may be due to different engine types (inline, V, opposed) and the use of different materials.

CONCEPT ACTIVITY 10-2 Engine Cleaning List all of the engine-cleaning equipment and solvents that are available in your shop and what they are used to clean. When listing the solvents, include the health-related precautions listed on the solvent container’s label or on its SDS. Answer Answers will vary but may include options such as solvent tanks, hot or cold cleaning tanks, and bead-cleaning cabinets.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 11: Lower End Theory and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 11: LOWER END THEORY AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4

SHORT ANSWER 1.

Describe how to inspect an oil pump.

Answer To inspect an oil pump: Carefully remove the pressure relief valve and note the direction it is pointing to so it can be reinstalled in its proper position. Inspect the relief valve spring for signs of collapsing or wear. Check the tension of the spring according to specifications. Also check the piston for scores and free operation in its bore. Remove the housing bolts, then remove the cover from the housing. Mark the gear teeth so they can be reassembled with the same tooth indexing. Once all parts have been removed, clean them and dry them off with compressed air. Inspect the pump gears or rotors for chipping, galling, pitting, or signs of abnormal wear. Check the mating surface for the pump cover for wear. Use a feeler gauge to check the clearance between the outer gear and pump body. Use a micrometer to measure the diameter and thickness of the rotors. Use a feeler gauge to check the clearance between the outer rotor and pump body.

2. What is cylinder taper?

Answer Cylinder taper is the difference in diameter between the bottom of the cylinder bore and the top of the bore just below the ridge.

3. Describe how to measure main bearing oil clearance.

Answer To measure the oil clearance of the main and connecting rod bearings:

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 11: Lower End Theory and Service

1) 2) 3) 4) 5) 6) 7)

Make sure the new bearings match the crankshaft journal diameters and main bearing bores.

Make sure the bore is clean and dry.

Put the new main bearings into each main bearing cap and the bearing bores in the cylinder block.

Make sure all holes are aligned.

Place the crankshaft onto the bearings.

The oil clearance is now measured with Plastigage.

If the oil clearance is not within specifications, the crankshaft needs to be machined or replaced, or undersized bearings should be installed.

4. Where does maximum cylinder bore wear occur and why?

Answer Maximum cylinder bore wear occurs at the top of the ring travel area.

5. List three types of compression rings.

Answer Compression rings can be cast iron, cast iron coated with molybdenum, or cast iron coated with chrome.

6. What is the purpose of a thrust main bearing?

Answer A main bearing with flanged sides is called a thrust bearing and is used to control the horizontal movement or end play of the shaft. Most thrust main bearings are double flanged.

7. How should the oil pump be primed when installing it into the engine?

Answer The preferred way is to submerge the pump in clean engine oil. Make sure the inlet port is fully in the oil. Then turn the pump until you see oil flow from the outlet of the pump.

8. What tools can be used to measure crankshaft end play?

Answer A dial indicator or a feeler gauge 9. Describe the pattern that should be present after the final honing of a cylinder wall.

Answer A criss-crossing pattern

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 11: Lower End Theory and Service

10. Describe how to check for crankshaft bearing journal wear.

Answer The journals can be measured with a micrometer for diameter and out-of-round.

11. Describe how to inspect a piston for wear.

Answer Inspect a piston for wear and damage. Measure the diameter of the piston and the pin bore and check for out-of-round.

MULTIPLE CHOICE 1.

Most pistons used today are made of ___. a. cast iron b. aluminum c. ceramic d. none of the above Answer: b. Aluminum pistons are most commonly used in automotive engines.

2. Cam bearings in OHV engines are typically which type? a. Split insert b. Full-round c. Thrust d. None of the above Answer: b. Cam bearings in OHV engines are located in the block and are pressed into the cam bearing bores using special tools.

3. Which of the following is not of concern when checking a piston? a. Diameter b. Surface finish c. Groove wear d. Pin boss wobble Answer: c. Pistons are checked for their correct diameter, surface finish, and wear on the pin boss.

4. Each half of a split bearing is made slightly larger than an exact half. What is this called? a. Spread b. Crush c. Both a and b d. Neither a nor b Answer: b. Bearing crush refers to each half of a split bearing being slightly greater than an exact half. Bearing spread means that the distance across the parting edges of the insert should be slightly greater than the diameter of the bearing bore.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 11: Lower End Theory and Service

5. The connecting rod journal is also called the ___. a. balancer shaft b. vibration damper c. Plastigage d. crankpin Answer: d. The connecting rod journal is also called the crankpin.

6. Which of the following are not typically found in the block of a modern engine? a. Pistons b. Crankshaft c. Valves d. Oil pump Answer: c. Valves are located in the cylinder head(s) of modern engines.

7. All of the following are functions of the flywheel, except it ___. a. provides a mounting place for the clutch assembly b. smooths out cylinder firing pulsations c. has marks used to set the valve timing d. meshes with the starter drive gear Answer: c. The flywheel supports the clutch assembly, smooths out crankshaft pulsations, and meshes with the starter drive gear to crank the engine during starting.

8. Which type of oil ring is slotted so that excess oil can pass through it? a. Cast iron b. Segmented c. Both a and b d. Neither a nor b Answer: c. Both cast-iron and segmented rings have slots to allow excess oil to pass through.

ASE-STYLE REVIEW QUESTIONS 1.

When removing the balance shaft assembly: Technician A inspects the bearings for unusual wear or damage. Technician B smoothens a damaged camshaft or balance shaft journal by lightly sanding it. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. If the camshaft or balance shaft bearings or journals are damaged, the shafts and bearing should be replaced. Never attempt to salvage the shafts.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 11: Lower End Theory and Service

2. After installing cam bearings: Technician A checks that the oil holes in the bearings are properly aligned with those in the block by squirting oil into the holes. Technician B checks for proper alignment by inserting a wire through the holes. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both methods may be used to check for proper alignment of the bearing oil hole with the block.

3. Technician A says that a cylinder wall with too smooth a surface will prevent the piston rings from seating properly. Technician B says that a cylinder wall should have a crosshatch honing pattern. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both statements are correct. The cylinder wall surface should have a crosshatch pattern and should not be so smooth that the rings are not able to seat properly.

4. Technician A installs a cup-type core plug with its flanged edge outward. Technician B installs a dish-type core plug with the dished side facing inward. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A cup-type core plug is installed with the flanged edges pointing outward; a dished-type plug is installed with the dished side facing outward, not inward as stated.

5. Technician A uses a micrometer to measure the connecting rod journal for taper.

Technician B uses a micrometer to measure the connecting rod journal for out-ofroundness. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. An outside micrometer is used to measure for both taper and out-ofroundness.

6. Technician A says that piston ring end gaps should be the same for each ring on a piston. Technician B says that piston ring end gaps should be aligned before installing the piston into its bore. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 11: Lower End Theory and Service

Answer: d. Piston ring end gaps should be staggered, and most manufacturers recommend locations for each ring. Piston ring end gap specifications vary according to ring location, with some manufacturers specifying a larger end gap for the second ring.

7. Technician A checks crankshaft oil clearance with a feeler gauge. Technician B uses a dial indicator to check crankshaft oil clearance. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Oil clearance is checked with Plastigage, and a dial indicator can be used to check for crankshaft thrust bearing wear or end play.

8. When removing the piston and rod assemblies from a cylinder block: Technician A positions the throw of the crankshaft at the top of its stroke and removes the connecting rod nuts and cap. Technician B covers the rod bolts with protectors and pushes the piston and rod assembly out with the wooden hammer handle or wooden drift and supports the piston as it comes out of the cylinder. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. When removing the piston and rod assemblies from a cylinder block, position the throw of the crankshaft at the bottom of its stroke. Remove the connecting rod nuts and cap. The caps and rods must remain as a set. Cover the rod bolts with protectors to avoid damage to the crankshaft journals. Carefully push the piston and rod assembly out with the wooden hammer handle or wooden drift and support the piston as it comes out of the cylinder.

9. Technician A says that crankshaft counterweights offset the weight of the connecting rods and pistons. Technician B says that crankshaft counterweights are used to dampen crankshaft torsional vibrations. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Counterweights are used to offset the weight of the pistons and rods. The crankshaft damper or harmonic balancer is used to dampen torsional vibrations.

10. Technician A uses a feeler gauge and straightedge to determine the pump cover flatness. Technician B uses an outside micrometer to measure the diameter and thickness of the outer rotor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A straightedge and feeler gauges are used to determine pump cover flatness, and an outside micrometer is used to measure the diameter and thickness of an oil pump outer rotor.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 12: Upper End Theory and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 12: UPPER END THEORY AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4

SHORT ANSWER 1.

Explain staged and continuously variable valve timing systems.

Answer Staged VVT systems allow for changes in valve lift, such as Honda’s VTEC system.

Continuously variable systems allow either the intake or both the intake and exhaust camshafts to change timing in relation to the crankshaft.

2. How does resurfacing the cylinder head of an OHC engine affect valve timing and what should be done when the head needs resurfacing?

Answer When the cylinder head on OHC engines is resurfaced, the removal of material from the head results in the camshaft being closer to the crankshaft, altering valve timing.

On some engines, special shims are used to raise the camshaft by the same amount as the material removed, thus restoring valve timing. On many engines, shims cannot be used and this is why manufacturers recommend replacing the head rather than resurfacing it.

3. Define valve margin.

Answer Valve margin is the area between the valve face and the head of the valve that allows for some machining of the valve face, which is sometimes necessary to restore its finish, and allows the valve an extra capacity to hold heat.

4. What usually causes warpage in an aluminum cylinder head?

Answer Warpage in an aluminum cylinder head is usually the result of overheating or uneven cooling within the cylinder head. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 12: Upper End Theory and Service

5. What are the two ways pushrods can be checked for straightness?

Answer Pushrods may be checked for straightness while installed in the engine by rotating them when the valve is closed and visually checking for indications of wobble. When the pushrods are out of the engine, they can be checked by rolling them on a flat surface; a pushrod that is not straight will appear to hop. The most accurate method is by using a dial indicator. If more than 0.003 (0.076 mm) TIR is found, the pushrod should be replaced.

6. Define rocker arm ratio.

Answer Rocker arm ratio is the increase in valve opening distance based on the position of the rocker arm pivot. By locating the pivot off-center, the valve can open further than the distance the rocker arm moves due to the cam lobe.

7. Which areas of the cylinder head are most prone to cracking?

Answer Around the valve seats.

8. Explain the benefits of variable valve timing.

Answer VVT improves performance, reduces fuel consumption, and can reduce exhaust emissions.

9. Explain the operation of cam phasers.

Answer Cam phasers change the position of the cam drive gear in relation to the camshaft, which alters the cam timing. Phaser position changes as oil is allowed to fill the space in the vane cavity or as oil flows out of the cavity. Some systems use electric stepper motors to change phaser position.

10. Explain valve overlap and how it is used to improve engine performance.

Answer Valve overlap is used to help empty the cylinder at high speeds and to draw in the intake charge into the cylinder.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 12: Upper End Theory and Service

MULTIPLE CHOICE 1.

Which of the following is not true of knurling? a. It is one of the fastest techniques for restoring the ID dimensions of a worn valve guide. b. It reduces the amount of work necessary to reseat the valve. c. It is useful for restoring badly worn guides to their original condition. d. None of the above.

Answer: c. Knurling does not restore a guide to its original condition.

2. To allow the engine to run on the Atkinson cycle, Toyota’s VVT-i system causes the ___. a. intake valve to open early b. exhaust valve to open late c. intake valve to close late d. exhaust valve to close early Answer: c. The system is reprogrammed to allow the intake valve to close later for the Atkinson cycle.

3. To ensure proper seating of the valve, the valve seat must be ___. a. the correct width b. in the correct location on the valve face c. concentric with the guide d. all of the above Answer: d. Proper seating and sealing requires proper fit and alignment between the valve seat and face.

4. Many engines with VVT have a phaser mounted to the end of one or more camshafts.

Which of the following statements is not true? a. A phaser is used to alter valve timing. b. Most phasers are controlled by oil pressure. c. Phasers are used to change valve lift. d. Phasers can be used to change valve overlap.

Answer: c. Phasers only alter the timing of valve events.

5. Multiple valve engines tend to be more efficient than two-valve-per-cylinder engines because they ___. a. allow for increased port areas b. have smaller valves c. provide less restriction to the airflow d. all of the above Answer: d. Airflow into and out of the combustion chamber is improved by using multiple small valves rather than a single large intake and single exhaust valve.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 12: Upper End Theory and Service

6. Which of the following is not a type of valve guide seal? a. Positive b. Negative c. Umbrella d. O-ring Answer: b. Valve seals are either positive (stationary to the valve) or umbrella/O-ring types (move with the valve). Negative valve seals do not exist.

7. What type of valve lifter automatically compensates for the effects of engine temperature? a. Hydraulic b. Solid c. Roller d. All of the above Answer: a. Hydraulic lifters operate using oil pressure to compensate for any play in the valvetrain caused by temperature changes.

8. What device in the valve train changes rotary motion into reciprocating motion? a. Eccentric b. Cam c. Bushing d. Mandrel Answer: b. The oblong shape of the cam lobe creates a linear reciprocating motion as the camshaft rotates.

ASE-STYLE REVIEW QUESTIONS 1.

While discussing the reasons for resurfacing a cylinder head: Technician A says it should be resurfaced to make it flat and very smooth so that the head gasket can seal properly during engine assembly. Technician B says that it can be resurfaced to raise the compression. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

Answer: b. If the surface is made very smooth, the metal will not be able to grip and the head gasket and poor sealing will result. For proper head gasket seating, the finish cannot be too smooth, decreasing the grip of the gasket, or too rough, preventing the gasket from conforming to the sealing surface.

2. While inspecting the timing gears of an engine: Technician A says a gear with cracks, spalling, or excessive wear on the tooth surface indicates improper gear backlash.

Technician B says the diameter of many of the engine’s timing gears and sprockets should be measured with the drive chain wrapped around the individual gears. Who is correct? a. Technician A b. Technician B © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 12: Upper End Theory and Service

c. Both A and B d. Neither A nor B Answer: a. Cracks, spalling, and excessive wear can occur on gear drive systems if the spacing (backlash) or contact between the gears is incorrect.

3. Technician A says that positive valve stem seals fit tightly around the top of the valve guide. Technician B says that positive stem seals scrape oil off the valve as it moves up and down. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Positive valve stem seals fit tightly around the stem and scrape excess oil off the valve as it moves up and down.

4. Technician A says to cylinder heads often crack between the valve seats and around the spark plug holes. Technician B says cracks often appear around the intake ports.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Cracks typically appear along high-stress areas of the combustion chamber, not around the ports.

5. Technician A says an engine may use one or more valve springs per valve. Technician B says additional valve springs are used to control vibration and increase total pressure.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Adding a second or third valve spring increases pressure and helps control vibration of the main spring.

6. Technician A says it is not necessary to measure valve stem height unless the valves have been replaced. Technician B says valve stem height can be adjusted with shims.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Valve stem height is critical for correct valvetrain operation and should be checked any time valves are removed, serviced, or replaced. Valve spring height may be adjusted with shims but valve stem height cannot.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 12: Upper End Theory and Service

7. While discussing the Valvetronic system: Technician A says the system has no need for a throttle plate. Technician B says the system alters the lift of the intake valves. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The Valvetronic system varies the lift and timing of the valves. Under light load, the intake valves open less. When more power is required, the valves open more, allowing more air into the engine. Because valve opening is controlling the airflow into the cylinders, a throttle body is not required.

8. While checking a hydraulic phaser after the camshaft has been removed from the engine: Technician A attempts to rotate the phaser’s timing gear by hand and replaces it if it does not move. Technician B applies air pressure to the advance and retard ports and replaces it if the gear does not move. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Typically, the phaser should not move by hand. When applying air pressure, the phaser should move.

9. While servicing a pair of aluminum cylinder heads: Technician A says if needed, both heads must be machined equally and the same amount of material removed from each. Technician B replaces both heads if the warpage exceeds the specified allowable amount. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. To maintain correct valvetrain geometry and timing system operation, both cylinder heads on V-type engines must be the same distance from the crankshaft.

Machining one head and not the other will affect the alignment of the intake manifold and timing system.

10. While discussing camshafts Technician A says valve lift is based only on the height of the cam lobe. Technician B says valve duration is based on the height of the lobe. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Valve lift is based on lobe size and the rocker arm ratio. Duration is affected by the shape of the lobe at the nose.

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6

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 13: Engine Sealing and Reassembly

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 13: ENGINE SEALING AND REASSEMBLY

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 3

SHORT ANSWER 1.

What are the major differences between aerobic and anaerobic sealants?

Answer Whether they cure in the presence or absence of air, and their gap-filling ability.

2. How does a torque-to-yield bolt differ from a standard bolt?

Answer TTY bolts stretch when torque. This prevents them from being reused as they are weakened and subject to breaking if reused. A bolt that has been stretched to its yield point will not return to its original length.

3. How do seals differ from gaskets?

Answer Seals are used in places where moving and non-moving parts come together, such as the spinning crankshaft where it passes through the block. Gaskets are used between two non-moving components.

4. Where are thread sealers most often used?

Answer Thread sealers are commonly used on bolts that thread into oil or coolant passages.

5. On hybrid vehicles, how can you identify the high-voltage cables and connectors?

Answer The high-voltage cables and connectors are orange.

© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 13: Engine Sealing and Reassembly

6. What is the difference between a hard and a soft gasket?

Answer A hard gasket is rigid and may contain several layers, including steel. A soft gasket is pliable and conforms easily to fit into place.

7. List four methods of valve lash adjustment.

Answer Valve lash may be adjusted by an adjustment screw and lock nut on the rocker arm, by replacing a shim, by replacing followers with ones of different thicknesses, and by setting the cam so the lobe is down and then turning the pushrod until resistance is felt and then tightening the rocker arm an additional amount.

8. What can result if proper engine prelubrication is not performed?

Answer Excessive engine wear and damage may result if the engine is started “dry” or without prelubrication.

MULTIPLE CHOICE 1.

Which of the following statements is incorrect? a. Cylinder head bolts must be tightened to the proper amount of torque. b. Most cylinder head bolts are tightened in a sequence that starts on one end. c. On some engines, the head bolts are retorqued after the engine has been run and is hot. d. Many engines use head bolts of different lengths.

Answer: b. Most cylinder head bolts are tightened in a sequence that begins in the center, not on one end as stated.

2. Which of the following statements about the purpose of a cylinder head gasket is not true? a. It seals intake stroke vacuum, combustion pressure, and the heat of combustion. b. It prevents coolant leakage and resists rust, corrosion and, in many cases, meters coolant flow. c. It allows for lateral and vertical head movement as the engine heats and cools. d. It meters lubricating oil onto the engine’s cylinder walls.

Answer: d. The cylinder head gasket does not meter oil onto the cylinder walls.

3. Graphite is ___. a. an anaerobic substance b. an RTV

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 13: Engine Sealing and Reassembly

c. an aerobic substance d. none of these Answer: d. Graphite is not an anaerobic or aerobic substance, nor is it a RTV. It is a lubricant.

4. Which of the following are considered soft, cut gaskets? a. Paper gaskets b. Cork gaskets c. Cork/rubber gaskets d. All of the above Answer: d. All of the above 5. What material is typically not used to form a rear main bearing oil seal? a. Polyacrylate b. RTV c. Silicone synthetic rubber d. Viton Answer: b. Rear main seals are not made of RTV. 6. Which of the following statements about preparing to assemble an engine is not true? a. Discard and replace all bolts that are damaged. b. Identify what bolts go into the specific bores. c. Use a thread locker on all bolts. d. Clean bolt and cylinder block threads with a thread chaser or tap.

Answer: c. Thread locker or similar material should only be used on bolts that are identified in the specs as needing this sealant.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that TTY bolts can be used after they were removed if there are no signs of distortion or stretching. Technician B says that head bolts that pass through a coolant passage should be coated with a nonhardening sealer prior to installing them.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Torque-to-yield bolts should not be reused. Head bolts that pass through a coolant passage should be coated with a non-hardening sealer.

2. Technician A uses adhesives to hold gaskets in place while installing them. Technician B uses RTV sealant on all surfaces that are prone to leaks. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 13: Engine Sealing and Reassembly

Answer: a. RTV should only be used where specified. Using RTV in other places may result in leaks or other problems.

3. Technician A uses soft gaskets on valve covers. Technician B uses soft gaskets on water pumps. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Soft gaskets may be used for both applications 4. While installing a timing belt: Technician A installs the belt, turns the crankshaft two full rotations, then applies tension to the belt. Technician B installs the belt, applies tension, then turns the crankshaft two full rotations. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Tension is applied to the timing belt and then the engine is rotated two crankshaft revolutions and the tension is rechecked.

5. Technician A says that oil pan gaskets are often made of cork due to its ability to conform to small imperfections in the oil pan. Technician B says oil pan and valve cover gaskets are often MLS gaskets to account for the different expansion rates between components. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Cork gaskets are not used in modern engines and have been replaced by RTV and other gasket materials. Multilayer steel gaskets are used for head gaskets and other critical surfaces.

6. Technician A says that aluminum expands at a different rate than cast iron. Technician B says that cast iron has a coefficient of thermal expansion two or three times greater than aluminum. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Aluminum expands at a greater rate than cast iron, not as stated by Technician B.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 13: Engine Sealing and Reassembly

7. While discussing proper engine break-in: Technician A says that the engine should run at idle speed for at least 2 hours. Technician B says that the engine should be accelerated from a stop at full throttle to 50 mph and that this cycle should be repeated at least 10 times. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Neither technique is recommended. After the engine has started, it should be run at about 1,500 rpm until it reaches operating temperature, not at idle speed as stated by Technician A. During the test drive, the vehicle should only be accelerated from 30 mph (48 km/h) to 50 mph (80 km/h) at least 10 times at full throttle. Some manufacturers of late model engines no longer recommend a break-in procedure.

8. While tightening a TTY bolt: Technician A initially tightens the bolt to the specified torque. Technician B turns the bolt an additional amount after the bolt has been tightened to the specified torque. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The correct procedure for tightening a TTY bolt involves two distinct steps: tighten the bolt to the specified torque, and then turn the bolt to a specified angle to load the bolt beyond its yield point.

9. Before reusing head or other critical bolts: Technician A measures their length and compares the measurement to specifications. Technician B lubricates the threads and the bottom of the bolt head with engine oil before installing them. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. These are steps that should be taken to prevent failure due to poor assembly practices.

10. While selecting the proper RTV for a particular application: Technician A uses RTV in a black tube for all high-temperature applications. Technician B uses RTV in a red tube for most general applications. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither is correct. Black RTV is for general purpose; blue is for special applications; and red is for high-temperature requirements. The correct type should always be used for a specific application.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 14: LUBRICATING AND COOLING SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 14-1 .......................................................................................................... 6 CONCEPT ACTIVITY 14-2 ......................................................................................................... 8 CONCEPT ACTIVITY 14-3 ........................................................................................................ 12 CONCEPT ACTIVITY 14-4 ........................................................................................................ 14

SHORT ANSWER 1. What is the most efficient way to increase a radiator’s efficiency?

Answer Increase the difference between the temperature of the coolant and the outside air flowing through it. The efficiency is also dependent on its basic design, the area and thickness of the core, and the amount of coolant going through the radiator.

2. Explain why a pressure relief valve is needed in an automotive oil pump.

Answer Since the oil pump is a positive displacement pump, an oil pressure relief valve is used to prevent excessively high system pressures from occurring as engine speed is increased.

3. List five problems that can be caused by engine overheating.

Answer Engine overheating can cause the following problems: detonation, preignition, blown head gasket, OHC cam seizure and breakage, blown hoses, radiator leaks, cylinder damage due to swelling pistons, sticky exhaust valve stems, and engine bearing damage.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

4. Describe the procedure for using air bleed valves to purge air out of a cooling system.

Answer To use the air bleeds, make sure the engine is warm and the heater is fully on.

Connect a hose to the end of the valves and place the open end in a catch can. Open all bleed valves. Slowly put the required amount of coolant into the radiator until the coolant begins to leak out of the valves. Then close the valves and top off the system.

5. Describe the simple test used to determine whether the water pump is providing good circulation.

Answer To determine whether the water pump is creating good circulation, warm up the engine and run it at idle speed. Squeeze the upper radiator hose with one hand and accelerate the engine with the other. If a surge of coolant is felt at the hose, the pump is circulating coolant.

6. List three possible causes of low engine oil pressure.

Answer Worn main bearings, worn rod bearings, worn oil pump, and restricted oil pickup 7. List two effects on driveability of having the wrong thermostat installed.

Answer An engine may run too cold, increasing fuel use and emissions.

8. Explain how the radiator cap increases cooling system boiling point.

Answer The radiator cap allows pressure to build in the system as the coolant expands as it gets hot. The increase in pressure raises the boiling point of the coolant.

9. Explain why special cooling system service precautions are necessary when working on hybrid and electric vehicles.

Answer A hybrid may have a coolant tank that keeps hot coolant for several days to aid in quick engine warm up. Also, hybrids have two cooling systems, one for the ICE and one for the hybrid drive system. The two systems are separate and use different coolants.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

MULTIPLE CHOICE 1.

Which of the following is a function of the engine’s lubrication system? a. Holds an adequate supply of oil b. Removes contaminants from the oil c. Delivers oil to all necessary areas of the engine d. All of the above Answer: d. The lubrication system must hold enough oil for engine operation, remove dirt and contaminates, and deliver the oil to all moving parts.

2. For every pound of pressure put on engine coolant, the boiling point of the coolant is raised about ___. a. 2 °F b. 3 °F c. 4 °F d. 5 °F Answer: b. Each pound of pressure on engine coolant raises the boiling point about 3 °F (–1.6 °C).

3. Which is not a typical method of driving the water pump? a. Accessory drive belt b. Electric motor c. Hydraulic motor d. Timing belt Answer: c. Automotive water pumps are usually belt-driven by the crankshaft or an electric motor.

4. Which of the following is not an effective way to determine if an engine has an internal coolant leak? a. Performing a pressure test on the system b. Visually inspecting the exhaust, coolant, and engine oil c. Using a dye penetrant and black light d. Using a combustion leak tester Answer: c. The use of a dye and black light is only effective for external leaks.

5. Cooling system hoses should be replaced when they are ___. a. hard (brittle) b. soft (spongy) c. swollen d. all of the above Answer: d. Hoses must remain pliable to allow movement but soft or swollen hoses indicate the hose material is breaking down and is weakened.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

6. Which of the following is not a true statement about thermostats? a. Faulty thermostats are often the cause of air pockets in the coolant passages. b. They can also cause an increase in fuel consumption and poor engine performance. c. If the thermostat is stuck open, the coolant may not reach the desired temperature because it is cooled before it gets hot. d. If a thermostat is stuck closed, coolant will not flow between the engine and radiator and the engine will quickly overheat.

Answer: a. Air in the system could not be caused by a faulty thermostat.

ASE-STYLE REVIEW QUESTIONS 1.

An engine overheats in traffic but is fine when driving: Technician A says a faulty thermostat may be the cause. Technician B says the fan clutch could be the cause.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. A faulty thermostat will cause overheating under all operating conditions due to the lack of coolant flow to the radiator. A faulty fan clutch will have a greater effect when in traffic and there is reduced ram-air flow across the radiator.

2. Technician A says that excessive engine-oil consumption can be caused by low oil levels. Technician B says that excessive oil consumption can be caused by worn valve guides. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Excessive oil consumption can result from external and internal leaks, or worn piston rings, valve seals, or valve guides. If the valve guides are worn, oil will be drawn into the cylinder during the intake stroke.

3. While checking for conditions that might cause coolant electrolysis: Technician A places the positive lead of a voltmeter into the coolant and connects the negative lead to a ground. Technician B checks for the presence of voltage in the coolant with the ignition off. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. To check for the conditions prone to electrolysis, set a voltmeter so it can read in tenths of a volt. Attach the negative meter lead to a good ground. Place the positive lead into the coolant. Look at the meter while the engine is cranked with the

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

starter, and record the readings. Take another reading with the engine running and all accessories turned on.

4. When discussing oil consumption: Technician A says using one-quart of oil every 2,000 miles is acceptable. Technician B says oil consumption may increase depending on driving conditions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Oil consumption specifications vary among manufacturers and the amount consumed can change based on vehicle-operating conditions.

5. Technician A says that if the PCV valve or connecting hoses become clogged, excessive pressure will develop in the crankcase and can cause oil leaks. Technician B says that if the PCV valve or connecting hoses become clogged, oil may be pushed into the air cleaner or cause it to be drawn into the intake manifold. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The PCV removes blowby gases which, if not removed, will increase pressure in the crankcase, resulting in oil leaks or allowing oil to back up into the intake air system.

6. While bleeding air from a cooling system: Technician A loosens a heater hose at its highest point. Technician B uses air bleed valves. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Depending on the cooling system, opening a heater hose connection may be required to remove air trapped in the heater core circuit. Some engines have air bleed valves to help remove trapped air.

7. While diagnosing an engine that overheats after frequent hard accelerations: Technician A checks for a collapsed lower radiator hose. Technician B checks the cooling fan electrical circuit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A collapsed lower hose can prevent adequate coolant flow from the radiator back into the engine, leading to overheating. If the electric cooling fan is not operating, the engine can overheat at lower driving speeds or under heavy loads.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

8. While performing a cooling system service on a hybrid vehicle: Technician A says it may be necessary to connect a scan tool to the vehicle. Technician B says it may be necessary to disable the high-voltage system before servicing the engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A scan tool may be required to operate the coolant pump(s) to bleed the system.

9. While discussing the causes of low engine oil pressure: Technician A says that contaminated and old engine oil could be the cause. Technician B says that a stuck pressure relief valve could be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A stuck pressure relief valve would cause high oil pressure under some operating conditions.

10. While diagnosing the cause of air bubbles in the coolant recovery tank: Technician A checks for a bad head gasket. Technician B checks the radiator cap. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A combustion leak from the head gasket can cause bubble to form in the cooling system. A defective radiator cap may not seal properly, also allowing air to enter the system.

TECH MANUAL CONCEPT ACTIVITY 14-1 Viscosity To provide an example of the viscosities of various liquids, obtain a Styrofoam or similar cup and, using a needle or other small object, poke a small hole in the bottom of the cup. Next, place a measured quantity of water in the cup, and note the frequency of the drips from the hole. Once the water is tested, repeat the test with samples of motor oil, automatic transmission fluid, and differential lubricant. Record your results below.

1.

Water drops per minute Answer Answers will vary but may include responses such as 60 drops per minute.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

2. Motor oil drops per minute Answer Answers will vary but may include responses such as 30 drops per minute.

3. ATF drops per minute Answer Answers will vary but may include responses such as 30 drops per minute.

4. Differential lubricant drops per minute Answer Answers will vary but may include responses such as 10 drops per minute.

5. If the oil was tested at a temperature below 32 °F (0 °C), what effect do you think that would have on the frequency of the drops?

Answer Answers will vary but may include responses such as fewer drops per minute.

6. If the oil was tested at a temperature above 180 °F (82.2 °C), what effect do you think that would have on the frequency of the drops?

Answer Answers will vary but may include responses such as increased drops per minute.

If possible, cool a container of engine oil, and retest.

7. Oil temperature ______________Drips per minute______________ Answer Answers will vary based on temperature.

Now, if possible, obtain engine oil that is hot, and retest.

8. Oil temperature ______________Drips per minute______________ Answer Answers will vary based on temperature.

9. Describe the results of testing the oil both cold and hot.

Answer Answers will vary but may include responses such as cold oil has fewer drops compared to warmer oil.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

10. Did the results of the cold/hot oil test coincide with your predictions in questions 5 and 6?

Answer Answers will vary.

11. Explain why the correct oil viscosity is important for the internal engine components.

Answer Oil that is too thin will not provide enough lubrication within bearing clearances. Oil that is too thick may not be able to form an oil film in very small bearing clearances.

12. What other problems, other than component lubrication, could result from using the incorrect weight of oil?

Answer Excessive oil consumption, rapid wear on cold starts

CONCEPT ACTIVITY 14-2 Density Place into a glass jar or similar container an equal amount of water and oil. To perform a more environmentally friendly version of this experiment, use vegetable oil instead of motor oil. Once both liquids are in the jar, let them settle for a few minutes, and observe what happens to the two liquids.

1.

Describe how the water and oil appear.

Answer Answers will vary but may include responses such as the oil and water separated.

2. Why do the oil and water separate?

Answer Water molecules bond together; oil molecules which are made of long chains of hydrocarbons and have a differing charge repel against the water and separate.

To test the density of liquids, you will need three jars or beakers for water, vegetable oil, and corn syrup. You will also need paper clips, raisins, and small balls of paper. Carefully place a paper clip into each jar, attempting to float the paper clip on each liquid (check all that apply).

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

3. Paper clip floats on: Water______________ Vegetable oil______________ Corn syrup______________ Answer Answers will vary.

Now try to get the raisin to float on each liquid.

4. Raisin floated on: Water______________ Vegetable oil______________ Corn syrup______________ Answer Answers will vary.

Last, ball up some small pieces of paper and see if they will float.

5. Paper balls floated on: Water______________ Vegetable oil ______________Corn syrup______________ Answer Answers will vary.

6. Were the results of the tests what you expected?

Answer Answers will vary based on results.

The density of water changes as the temperature of water changes. Water is at its most dense at about 39 °F (4 °C) and decreases in density up to its boiling point of 212 °F (100 °C).

Repeat the experiment above by trying to float objects on water, but this time use hot and cold water.

7. Water temperature: ______________Did the paper clip float? ______________ Answer Answers will vary.

8. Water temperature: ______________Did the paper clip float? ______________ Answer Answers will vary.

Why is it important to understand specific gravity and how it is affected by temperature?

Both cooling systems and batteries are tested by using hydrometers, which determine the concentrations of coolant and battery acid based on measurements of specific gravity.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

Specific gravity tests are performed on engine coolant to determine the concentration of coolant to water. Coolant should be mixed 50/50 with water for proper cooling system operation. One method of determining this mixture is by using a coolant hydrometer (Figure 14-1). Coolant hydrometers, both the floating disc/ball-and-dial types, rely on the coolant’s density to indicate coolant effectiveness. But as you saw in the experiments above, temperature has an effect on water’s specific gravity. To accurately use a hydrometer to test coolant, the reading must be temperature-compensated. Another problem with coolant testing is that newer propylene glycol-based coolants cannot be tested with a hydrometer.

FIGURE 14–1 A hydrometer is used to check the coolant for protection against freezing.

For many years batteries have been tested with hydrometers. The concentration of sulfuric acid and water, when corrected for temperature, can provide an indication of battery charge and condition. Many modern batteries are sealed, however, and hydrometer readings are not possible.

A refractometer should be used to more accurately determine engine coolant condition (Figure 14-2). A refractometer can measure ethylene glycol- and propylene glycol-based coolants, as well as battery acid. Have you noticed that if you look at a stick, a pole, or even yourself in a body of water, the object (or you) appears to have bent at an angle below the surface of the water? The reason for that effect is that light passes through liquids more slowly than it does through air. A refractometer measures the amount that light bends as it passes through a liquid, providing a reading of the percentage of concentration. However, just as reading with a hydrometer must be temperature-compensated, so must readings with a refractometer. Fortunately, because a refractometer needs only a drop or so of liquid for testing, by placing the sample of the liquid on the tester, it will soon assume the temperature of the tester.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

FIGURE 14–2 A refractometer shows specific gravity as well as the protection factor.

9. Measure the temperature of the water being tested; then place a drop of water on a refractometer and record its specific gravity.

Temperature ______________ Specific Gravity ______________ Answer Answers will vary.

10. Perform the same test with a sample of coolant.

Temperature ______________ Specific Gravity ______________ Answer Answers will vary.

11. Retest the sample of coolant, using a hydrometer, and record the indicated specific gravity.

Answer Answers will vary.

12. Note any difference in readings.

As you may see, temperature affects the specific gravity of the water and coolant.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

CONCEPT ACTIVITY 14-3 Engine Construction Materials Inspect a vehicle in your lab and note the materials that make up the major engine components.

1.

Engine block material Answer Answers will vary but may include responses such as aluminum or cast iron.

2. Cylinder head material Answer Answers will vary but may include responses such as aluminum or cast iron.

3. Intake manifold material Answer Answers will vary but may include responses such as aluminum or plastic.

4. Which of the materials listed above will expand and contract the most over the engine’s operational temperature range?

Answer Answers will vary but may include responses such as aluminum expands more than cast iron.

5. List the gaskets and seals that are affected by these components expanding and contracting.

Answer Answers will vary but may include responses such as intake manifold and cylinder head gaskets.

As the engine warms, the coolant expands. When the engine is shut off and cools, the coolant contracts and is drawn back into the engine. This is why cooling systems are equipped with coolant reservoir bottles. On systems with pressure tanks, space is provided to allow for coolant expansion. Both systems have both hot and cold full-fill markings.

The combination of heat and expansion creates pressure in the cooling system. As the pressure increases, the boiling point of the coolant increases.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

6. At what temperature does water boil?

Answer 212 °F Locate a cooling system cap from several lab vehicles.

7. What is the system pressure listed on the caps?

Answer Answers will vary but may include ranges such as 10–20 psi.

For every 3 psi increase in pressure, the boiling point will increase about 10 °F. 8. For each cooling system cap, determine the boiling point based on the pressure listed on the cap.

Answer Answers will vary based on caps.

With a pressure cap installed on the radiator or pressure tank, system pressure increases up to a certain amount, often between 13 and 16 psi, though some newer systems are approaching 30 psi. If the preset pressure limit is reached, the cap will allow the coolant to vent.

Before continuing, obtain permission from your instructor to operate a lab vehicle. With the engine cold, remove the radiator cap, and ensure the coolant level is full. Reinstall the cap. Next, check the coolant level in the overflow reservoir. Place a mark on the reservoir with a grease pencil or similar marker. Start the engine and allow it to reach operating temperature. Monitor coolant temperature via the temperature gauge on the dashboard or a computer scanner. Once the engine is fully warmed, shut the engine off, and note the coolant level in the reservoir. Place a mark at the level of the coolant. Determine the volume of coolant displaced by expansion into the reservoir. This can be done in a couple of ways: by direct measurement of the amount of coolant or by approximating the size of the reservoir and figuring the displacement.

9. How much coolant is displaced by expansion?

Answer Answers will vary but may include: one to two pints Find the cooling system capacity in the service information or manual.

10. What percentage of the total cooling system capacity is displaced when the engine is hot?

Answer Answers will vary but may include responses such as 5–10 percent

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

11. What factors do you think affect how much coolant is displaced?

Answer Answers will vary but may include responses such as volume of system and temperature of coolant.

12. Explain why the coolant reservoir or the pressure tank is not filled to the top with coolant.

Answer Both need room for expansion, and if filled to the top, the coolant would overflow when hot.

As the engine and cooling system heat up, coolant is displaced into the reservoir or recovery tank. As the engine and cooling system cool, the displaced coolant is returned to the cooling system.

13. What cooling system component is responsible for allowing the coolant to flow out and back from the reservoir?

Answer Radiator cap 14. How would a leak in the cooling system affect the operation of the coolant recovery system?

Answer A leak will allow coolant out and air back in.

CONCEPT ACTIVITY 14-4 Heat Transfer The ability of the cooling system, and the lubrication system as well, to transfer heat is critical. Without sufficient heat transfer from either system, the engine would quickly be destroyed. Engine oil and coolant are both used to transfer heat from various components.

1.

Describe how heat is transferred and removed by engine oil.

Answer Oil allows heat to move from engine components into the oil, which is then dissipated into the air circulation through the crankcase and by an oil cooler if present.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 14: Lubricating and Cooling Systems

2. Describe how heat is transferred and removed by coolant.

Answer Heat is removed from engine components and absorbed by the coolant, which then transfers the heat to the surrounding air of the surface of cooling system components.

3. How does the condition of the fins on the radiator affect its ability to transfer heat?

Answer Radiator fins provide a large surface area over which air moves and removes heat. If the fins are damaged, air will not be able to flow across them.

4. Describe other factors that can affect the ability of the lubrication and cooling systems to remove heat from the engine.

Answer Answers will vary but may include responses such as oil and coolant type and condition, surface area of components, air flow across radiators and oil coolers, oil and coolant flow rates.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 15: BASICS OF ELECTRICAL SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 15-1 .......................................................................................................... 7 CONCEPT ACTIVITY 15-2.......................................................................................................... 9 CONCEPT ACTIVITY 15-3......................................................................................................... 10 CONCEPT ACTIVITY 15-4 ........................................................................................................ 14 CONCEPT ACTIVITY 15-5......................................................................................................... 17 CONCEPT ACTIVITY 15-6 ........................................................................................................ 18 CONCEPT ACTIVITY 15-7......................................................................................................... 19 CONCEPT ACTIVITY 15-8 ....................................................................................................... 20 CONCEPT ACTIVITY 15-9 ........................................................................................................ 21

SHORT ANSWER 1.

What is represented by the E, I, and R in the formula E = IR? Answer In Ohm’s law, which expresses the mathematical relationship between current, voltage, and resistance, the E= voltage, I= Amperage, and R= Resistance.

2. What are the two types of wires and which is the most commonly used in automobiles?

Answer The two types of automotive wiring are solid and stranded, with stranded wiring being the most common.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

3. Define voltage drop.

Answer Voltage drop is the amount of voltage required to cause current flow through a load.

4. Define circuit protection.

Answer Circuit protection consists of fuses, circuit breakers, and similar devices that open a circuit when excessive current flow occurs.

5. What happens in an electrical circuit when the resistance increases?

Answer An increase in resistance in a circuit produces a reduction of current flow.

6. What is the difference between voltage and current?

Answer Voltage refers to electrical pressure; current refers to the amount of electron flowing past a certain point.

7. What is an SPST switch?

Answer A switch that is identified as SPST is a single-pole, single-throw switch or, in other words, a simple on-off switch such as would be used in a simple circuit.

8. Solve the parallel circuit for total circuit resistance, total circuit amperage, and the amperage through each leg (Figure 15-66).

FIGURE 15–66 Answer Total circuit resistance equals 1 ohm and total amperage is 12 amp. The current through the 6 ohm branch is 2 amps, current through the 3 ohm branch is 4 amps, and the current through the 2 ohm branch is 6 amps.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

MULTIPLE CHOICE 1.

Which type of resistor is commonly used in automotive circuits? a. Fixed value b. Stepped c. Variable d. All of the above Answer: d. All three types, fixed, stepped, and variable are used in systems such as computer power circuits, blower motor controls, and sensors that vary voltage based on movement.

2. Which of the following is not a characteristic of parallel circuits? a. Total circuit resistance is always less than the resistance of the leg with the lowest total resistance. b. The current through each leg will be different if the resistance values are different. c. The sum of the resistance in each leg equals the total circuit resistance. d. Source voltage will be dropped across each leg of the parallel circuit.

Answer: c. The total resistance through a parallel circuit is calculated by using the reciprocal formula based on the resistance of each leg of the circuit.

3. Which of the following states that the sum of the voltage drops in a closed circuit equals the voltage applied to the circuit? a. Ohm’s law b. Watt’s law c. Kirchhoff’s law d. Power law Answer: c. Kirchoff’s law states that the total voltage available in a complete circuit will be by the loads on the circuit.

4. Which of the following is not a true statement about blade fuses? a. They are available in several different sizes. b. They are color coded according to their voltage capacity. c. They are normally in an underhood fuse block. d. They allow the vehicle’s electrical system to be broken down into small circuits.

Answer: b. They are color coded according to their amperage capacity.

5. Which of the following is commonly used as a transmission neutral start switch? a. Mercury b. Momentary c. MPMT d. SPST Answer: c. A multiple-pole multiple-throw switch allows for more than one connection between circuits.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

6. All of the following are examples of circuit protection devices except: a. b. c. d.

Fuse link Relay Circuit breaker Voltage limiter

Answer: b. Relays allow a low power circuit to control the operation of a higher power circuit but does not include protection for overloading either circuit.

7. Which of the following is not a factor in a wire’s resistance? a. Length of the wire b. Wire temperature c. Diameter of the wire d. Insulation material Answer: d. Insulation material prevents the conductor from contacting other components and has no effect on conductor resistance.

8. A taillight circuit is being voltage drop tested. Technician A says excessive voltage drop on the light’s power circuit could cause the fuse to blow. Technician B says excessive voltage drop on the light’s ground circuit could cause the light to be dim. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Voltage drop will decrease current flow, which will not cause a fuse to blow. Reducing current and voltage to the bulb will reduce its brightness.

ASE-STYLE REVIEW QUESTIONS 1.

While discussing resistance: Technician A says that current will decrease with a decrease in resistance. Technician B says that current will decrease with an increase in resistance. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A decrease in resistance will result in increased current, and current will decrease as resistance increases according to Ohm’s law.

2. Technician A says that a 12-volt light bulb that draws 12 amps has a power output of 1 watt. Technician B says that a motor that has 1 ohm of resistance has a power rating of 144 watts if it is connected to a 12-volt battery. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

Answer: b. Using the formula P = E × I, a 12-volt light bulb drawing 12 amps would have a power output of 144 watts, not 1 watt as stated. An electric motor with 1-ohm resistance would draw 12 amps of current (I = E/R = 12/1 = 12). Using the formula P = E × I = 12 × 12 = 144, there would be a power output of 144 watts.

3. While discussing the circuit shown in Figure 15-67: Technician A says that the total resistance of the circuit is 1 ohm. Technician B says that the current flow through the 6 ohms of resistance is 12 amps. Who is correct?

FIGURE 15–67 a. b. c. d.

Technician A Technician B Both A and B Neither A nor B

Answer: d. Technician A is correct; using the reciprocal formula we find that the resistance total in the circuit is 1 ohm. Using Ohm’s law to find the current flow through the 6-ohm resistor (12/6 = 2), we find that there will be 2 amps flowing through it, not 12 amps as stated.

4. While discussing electrical grounds: Technician A says that a component may be grounded through its mounting to a major metal part. Technician B says that some components must be grounded by connecting its positive terminal to a metal section of the frame. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct; if a wire is connected from the positive terminal to a metal portion of the frame, the component will not be grounded and the connection will cause a problem called a direct short.

5. While discussing voltage drop: Technician A says voltage drops in a closed circuit must equal source voltage. Technician B says that voltage drops can be calculated by multiplying circuit voltage times the load’s resistance. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct; if the circuit is closed, all of the voltage that leaves the battery will be dropped or used as the current completes the path back to the battery.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

6. While discussing electrical relays: Technician A says that the relay’s coil is energized when the circuit’s control switch is open. This action connects power to the load circuit. Technician B says that a relay is an electric switch that allows a large amount of current to control a low-current circuit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. A relay is an electric switch that allows a small amount of current to control a high current circuit. And, the relay coil is energized when the control switch is closed. This action connects battery power to the load.

7. While discussing copper wire: Technician A says that if the length of wire is doubled, the resistance between the wire ends is doubled. Technician B says that if the diameter of a wire is doubled, the resistance between the wire ends is doubled. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct; if the length is doubled, the resistance between the wire ends is doubled. If the diameter of a wire is doubled, the resistance for any given length is cut in half. The larger the wire’s diameter, the lower the resistance.

8. While discussing current flow: Technician A says that current results from electrons being attracted to protons. Technician B says that for practical purposes, it is best to remember that current flows from a point of higher potential to a point of lower potential. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Electrons flow through a circuit from a source of high electrical potential to a place of lower potential.

9. While discussing voltage: Technician A says that voltage is the force developed by the attraction of the electrons to protons. Technician B says that the force developed by the attraction of electrons to protons is called electromotive force and it is measured in volts. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Voltage is the force developed by the attraction of the electrons to protons. The more positive one side of the circuit is, the more voltage is

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

present in the circuit. Voltage is the pressure that causes current flow. To have current flow, some force is needed to move the electrons between atoms. This force is called electromotive force (EMF) and is measured in units called volts. One volt is the amount of pressure required to move 1 ampere of current through a resistance of 1 ohm.

10. While discussing the AWG system: Technician A says that most automotive wiring range from 0 to 4 gauge. Technician B says that the higher the gauge number, the larger the diameter of the wire. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither is correct. Most automotive wiring ranges from number 10 to 18 with battery cables normally 4 gauge or lower. And, sizes are identified by a numbering system ranging from number 0 to 20, with number 0 being the largest and number 20 the smallest in a cross-sectional area.

TECH MANUAL CONCEPT ACTIVITY 15-1 Static Electricity Almost everyone is familiar with two very common electrical occurrences: lightning and static electricity. Lightning is actually an electrical discharge due to static electricity, just like when you get shocked touching a doorknob on a dry winter day. The difference is the energy in a lightning bolt is many, many times greater.

1.

Describe what you think are the conditions necessary for getting a static electricity shock.

Answer Answers may include responses such as an accumulation of electrical charges in substances normally not conductive.

2. Why do you think a lightning discharge is so much more powerful than a static electricity shock?

Answer Vast amounts of interaction within the volume of the clouds allow for a much greater charge to develop.

The term static electricity refers to a build-up of an electrical charge where there is typically poor electrical conductivity. When there is an electrical charge, there is the potential for electron flow. When an electron leaves an atom, it leaves behind an opening. The atom from which the electron left will now have a positive charge due to the loss of the negatively © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

charged electron. The atom the electron moved to now has a negative charge. Whenever an imbalance occurs, there is the potential for electrical current flow. When an electrical force is present, and electrons move from atom to atom, electrical current flow exists. If a material does not easily accept the movement of electrons, it is an insulator or a poor conductor.

Metals such as copper, silver, gold, and aluminum can readily give up and transfer electrons and are considered good electrical conductors (Figure 15-1).

If during this static electricity transfer, dissimilar charges are present, the charges will attract. If the charges are similar, the charges will repel — just as two magnets will repel if the north poles are placed close together and attract if the north and south poles are near each other. If you have ever pulled a wool sweater over your head and had your hair stand on end, you have experienced this phenomenon. When you pulled the sweater over your head, electrons transferred from the wool to your hair. Similarly, rubbing a balloon against a sweater can cause enough of a static charge to allow the balloon to “stick” to a wall.

FIGURE 15–1 Conductors are atoms with loosely bound outer electrons.

3. Inflate two balloons and attach a length of string to each knotted end. Rub one balloon against a piece of clothing. Then hold the string so that the balloons hang down near each other. Describe what takes place.

Answer Answers will vary but may include responses such as balloons move away from each other.

4. Rub the balloons against your clothing and attempt to stick them to various surfaces.

What surfaces stuck the best? Which were the worst?

Answer Answers will vary but may include responses such as plastic and drywall, concrete.

5. Describe why you think some surfaces hold the balloons better or worse than others.

Answer Answers will vary but may include responses such as the type of charge present at the material dry air.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

6. What environmental factors affect static electricity?

Answer Answers will vary.

CONCEPT ACTIVITY 15-2 Magnetic Fields Obtain a magnet and some iron shavings from your instructor. Place a piece of construction paper on top of the magnet. Then sprinkle some of the shavings on the paper over the magnet.

1.

What shapes do the shavings show on the paper?

Answer Answers will vary but may include responses such as shavings would be arranged along the magnetic lines of force.

2. Describe why the shavings appear in the patterns you see.

Answer Answers will vary but may include responses such as shavings would be following the lines of force.

Ask your instructor for a magnetic compass. To use the compass as an electrical current detector, place it along the positive or negative battery cable of a vehicle. Place the compass so the needle is parallel with the cable.

3. Turn on the headlights and describe the reaction of the compass.

Answer Answers will vary but may include responses such as the needle may move in response to the magnetic field.

4. Why did the compass react the way it did?

Answer Answers will vary but may include responses such as current flow along the wire creates a magnetic field.

5. How would the compass react to a smaller electrical load than the headlights?

Answer Answers will vary but may include responses such as there would be less needle movement.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

CONCEPT ACTIVITY 15-3 Ohm’s Law Using Ohm’s Law, depicted in Figure 15-2, solve the problems in Figures 15-3 through 15-6.

FIGURE 15–2 Ohm’s law.

Problem 1: Series Circuit

FIGURE 15–3 Series circuit.

Calculate the following values: 1.

Total circuit resistance: _____________________ Answer 4 ohms

2. Total circuit amperage: _____________________ Answer 3 amps 3. Voltage drop of lamp: _____________________ Answer 6 volts 4. Voltage drop of resistance: _____________________ Answer 6 volts 5. Current through lamp: _____________________ Answer 3 amps © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

6. Current through resistance: _____________________ Answer 3 amps 7. What effect does the unwanted resistance have on the circuit?

Answer It uses voltage available for the lamp, making the lamp dim.

8. What steps would you take to diagnose this concern?

Answer Answers will vary but should include options such as voltage drop testing.

9. What are three possible causes of this concern?

Answer Poor connection(s), corrosion, damaged conductor Problem 2: Parallel Circuit

FIGURE 15–4 Parallel circuit.

Referring to Figure 15-4, calculate the following values: 1.

Total circuit resistance: _____________________ Answer 1.333

2. Total circuit amperage: _____________________ Answer 9.xxx depending on the number of decimals for answer 1

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

3. Voltage drop of Lamp 1: ________________________Lamp 2: ________________________ Answer 12 volts and 12 volts 4. Current through Lamp 1: ________________________Lamp 2: ________________________ Answer 6 amps and 3 amps 5. Why is the current flow through each lamp different?

Answer Each lamp has a different resistance.

6. How is the total circuit current flow affected by the resistances?

Answer As resistance increases, the current flow decreases, and as resistance decreases, the current flow increases.

Problem 3: Series-Parallel Circuits

FIGURE 15–5 Series-parallel circuit.

Referring to Figure 15-5, calculate the following values.

1.

Total circuit resistance: Answer 2 ohms

2. Total circuit amperage: Answer 6 amps

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

3. Voltage drop of Lamp 1: ________________________ Lamp 2: ________________________ Lamp 3: ________________________ Lamp 4: ________________________ Answer 8 volts, 4 volts, 4 volts, 8 volts 4. Current through Lamp 1: ________________________ Lamp 2: ________________________ Lamp 3: ________________________ Lamp 4: ________________________ Answer 2 amps, 2 amps, 4 amps, 4 amps 5. Current through Branch 1 (resistances 1 and 2): ________________________ Branch 2 (resistances 3 and 4): ________________________ Answer 2 amps, 4 amps 6. Why are the voltage drops for each resistance different?

Answer Each load has a different resistance.

Problem 4: Series-Parallel Circuits

FIGURE 15–6 Series-parallel circuit.

Referring to Figure 15-6, calculate the following values: 1.

Total circuit resistance: Answer 2 ohms

2. Total circuit amperage: Answer 6 amps

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

3. Voltage drop of Lamp 1: ________________________Lamp 2: Resistance: ________________________ Answer 6 volts, 6 volts, 6 volts 4. Current through Lamp 1: ________________________Lamp 2: Resistance: ________________________ Answer 3 amps, 3 amps, 6 amps 5. Why is the current flow through each lamp different?

Answer Each lamp uses a portion of the amperage of the whole circuit.

6. How is the total circuit current flow affected by the resistance?

Answer As resistance increases, the current flow decreases and vice versa.

7. If this were a taillight circuit, how would the unwanted resistance affect the operation of the circuit?

Answer It would cause the light to be dim.

8. What steps would you take to diagnose this concern?

Answer Answers will vary but should include options such as voltage drop testing.

CONCEPT ACTIVITY 15-4 Circuit Operation Obtain from your instructor several automotive exterior lights with sockets. Bulb types 194, 1156, and 1157 (or similar) work well. Construct circuits using the diagrams below and record your findings.

1.

(Figure 15-7) Series circuit.

FIGURE 15–7 Series circuit.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

2. (Figure 15-8) Series circuit.

FIGURE 15–8 Series circuit.

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

3. (Figure 15-9) Parallel circuit.

FIGURE 15–9 Parallel circuit.

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

4. (Figure 15-10) Parallel circuit.

FIGURE 15–10 Parallel circuit.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

5. (Figure 15-11) Series-parallel circuit.

FIGURE 15–11 Series-parallel circuit.

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

6. (Figure 15-12) Series-parallel circuit.

FIGURE 15–12 Series-parallel circuit.

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

7. (Figure 15-13) Series-parallel circuit.

FIGURE 15–13 Series-parallel circuit.

Battery voltage: ________________________ Circuit resistance: ________________________ Voltage drops: ________________________ Ohm’s Law predicted amperage: ________________________ Measured amperage: ________________________ Answer Answers will vary.

CONCEPT ACTIVITY 15-5 Schematic Components Identify the following wiring diagram components:

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

Answer Battery Resistor Ground Rheostat Potentiometer

single pole single throw switch SPST normally open switch multiple relay fuse, circuit breaker, fuse link

pole multiple throw switch

CONCEPT ACTIVITY 15-6 Measurement Conversion Convert the following values: 1.

3.7 ohms = _____________________ K ohms Answer 0.0037

2. 641 mV = _____________________ volts Answer 0.641 3. 0.783 K ohms = _____________________ ohms Answer 783 4. 0.445 volts = _____________________ mV Answer 445

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

5. 20 mA = _____________________ amps Answer 0.020 6. 337 mA = _____________________ amps Answer 0.337 7. 1.2 M ohms = _____________________ ohms Answer 1,200,000 8. 8375 ohms = ____________________ K ohms Answer 8.375 9. Using a DMM provided by your instructor, list the various setting ranges for the following. If the meter has auto-ranging, list the scales available by pressing the scale button. a. Voltage ranges: _____________________, _____________________,_____________________ , _____________________ b. Resistance ranges: _____________________, _____________________,____________________ , _____________________ c. Amperage ranges: _____________________, _____________________,_____________________ , _____________________ Answer Answers will vary but may include responses such as 20V, 200V, 40 ohms, 400 ohms, 400 mA, and 10 A.

CONCEPT ACTIVITY 15-7 Fuse Identification 1.

Match the fuse amperage rating to its correct color: 4A _____________________Red 5A _____________________Pink 10A _____________________Yellow 15A _____________________Light blue 20A _____________________Light green 25A _____________________Tan 30A _____________________Natural

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

Answer 4A = pink 5A = tan 10A = red 15A = blue 20A = yellow 25A = natural 30A = green Installing a higher amp fuse can cause damage to the circuit and wiring.

2. Why is it important to replace a blown fuse with one of the correct voltage and amperage ratings?

Answer Excessive current could flow before the fuse opened, which could cause damage to components and wiring.

3. Describe what could happen if a blown fuse were replaced with one of too high of an amperage rating.

Answer Answers will vary but may include responses such as increased current flow can damage wiring and connectors.

CONCEPT ACTIVITY 15-8 Relay Identification Referring to Figure 15-14, identify the components of the relay: 1.

Define the purpose of a relay.

FIGURE 15–14 Relay identification.

Answer a. power from source b. power out to load

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

c. d. e. f. g.

circuit control core coil ground to allow a small current to control a larger current

Obtain a relay from your instructor.

2. Measure the resistance of the relay coil: _____________________ ohms Answer Answers will vary.

3. Is the coil resistance acceptable?

Answer Answers will vary.

4. What could cause the relay coil resistance to be lower than specifications?

Answer A shorted relay coil could cause this.

5. What could be the result of the relay coil resistance being too low?

Answer Excessive current flow could be the result.

CONCEPT ACTIVITY 15-9 Fuse Block Identification Refer to Figures 15-15 and 15-16 to complete the following table: TABLE 15–1 Fuse Block Identification.

Fuse/Relay Location # 38

Fuse Size

Circuit Description

Fuse/Relay Type

Fuse Color

Radio 40 6 Fuel pump

Micro relay

25

Orange Diode

12

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 15: Basics of Electrical Systems

FIGURE 15–15 Identification figure for fuses in Table 15-1.

FIGURE 15–16 Identification figure for fuses in Table 15-1.

Answer 38 29 5 6 14 19,20,22,23,24,26 25 Above 25 12

Empty 10A 40 30A

15A

n/a Radio Ign main Cool fan 1 Fuel pump Spare Ele ign

Cool fan 1

n/a Mini fuse Maxi Maxi Micro relay

n/a red orange green

Mini

blue orange

Diode Mini relay

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 16: GENERAL ELECTRICAL SYSTEM DIAGNOSTICS AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 16-1 .......................................................................................................... 6 CONCEPT ACTIVITY 16-2 ......................................................................................................... 7 CONCEPT ACTIVITY 16-3 ......................................................................................................... 8 CONCEPT ACTIVITY 16-4 ......................................................................................................... 8 CONCEPT ACTIVITY 16-5 ......................................................................................................... 9

SHORT ANSWER 1.

How will an electrical circuit behave if there is a short in the circuit?

Answer If there is a short to power, an unwanted connection between two circuits may result in one circuit operating when the second circuit is turned on. A short to ground can cause a fuse to open or can even overheat wiring and cause a fire.

2. What happens to an electrical circuit when there is unwanted resistance in it?

Answer When there is unwanted resistance in a circuit, current flow will be lower than normal and the components in the circuit will not operate normally.

3. What is indicated by a reading of battery voltage on the ground side of a component?

Answer The ground circuit is open.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

4. What type of solder should be used to repair electrical wiring?

Answer Electrical wiring should be repaired using rosin-core solder.

5. Why should only high-impedance meters be used on modern vehicles?

Answer High-impedance meters reduce the current flow caused by the meter being placed into the circuit for testing. This reduces the possibility of damage to electronic components.

6. Explain how a test light can be used to test for power and ground.

Answer A test light can be connected to ground to check for power or it can be connected to power to check for ground. If the light completes a path from power to ground, it will light.

7. Describe the procedure to perform a voltage drop test.

Answer Voltage drop is tested by placing the meter’s leads across a component or connection, such as the power wire going into and out of a connection. The circuit is turned on and the amount of voltage used or dropped by the connection is shown on the meter.

8. Why is a voltage drop test a more accurate test to check for unwanted resistance?

Answer Voltage drop testing occurs with the circuit in operation and under load. The meter will measure the actual voltage available based on circuit resistance and current flow.

A resistance test only measures the resistance of the circuit when it is off and no load is in operation so readings do not reflect what actually takes place during operation.

MULTIPLE CHOICE 1.

An ammeter is always connected in ___ with the circuit, whereas a voltmeter is connected in ___ with the circuit. a. parallel; series b. parallel; parallel c. series; parallel d. series; series

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

Answer: c. An ammeter is always connected in series with the circuit, while a voltmeter is connected in parallel with the circuit.

2. Which of the following is not a typical cause of unwanted or high resistance in a circuit? a. Corrosion on terminal ends b. A power wire contacting the chassis c. Loose or poor connections d. Frayed and damaged wires Answer: b. A power wire that is contacting the chassis would be an example of a short to ground, not high resistance.

3. Wiring harnesses are typically shielded by plastic conduit. What color is normally used to shield SRS-related wiring? a. Black b. Green c. Yellow d. Orange Answer: c. Yellow is used to shield SRS wires.

4. Which of the following lab scope controls must be set when trying to observe how long an event takes place? a. Intensity b. Vertical c. Horizontal d. Trigger Answer: c. Use the horizontal control. The horizontal scale measures time.

5. Which of the following statements is true? a. A short to ground causes decreased current flow. b. An open causes unwanted voltage drops. c. High-resistance problems can cause damage to wiring and connections. d. High-resistance problems may cause a fuse to blow.

Answer: c. Damaged wiring and connectors can cause poor connections and increase resistance in a circuit 6. Which of the following information is not given in a wiring diagram? a. Wire-by-wire color coding b. Location of wire harness travel c. Terminal designation d. Component designations Answer: b. The physical location of wiring harnesses and components are not given in a wiring diagram.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

ASE-STYLE REVIEW QUESTIONS 1.

While discussing electricity: Technician A says that an open causes unwanted voltage drops. Technician B says that high-resistance problems cause increased current flow.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. An open circuit causes a complete loss of current flow through the circuit; without current flow, there will be no voltage drops across the various loads. Highresistance problems cause decreased current flow, not increased flow as stated by Technician B.

2. While discussing NTC thermistors: Technician A says that some systems use this type of thermistor as a protection device. Technician B says that when there is high current in a circuit, the resistance of the thermistor increases and causes a decrease in current flow. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. A PTC, not a NTC, thermistor may be used as a circuit protection device.

When there is high current, the resistance of a PTC thermistor increases and causes a decrease in current flow.

3. While measuring the resistance of a wire with an ohmmeter: Technician A says that if low resistance is shown on the meter, the wire is shorted. Technician B says that if infinite resistance is measured, the wire is shorted. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. The best way to check a wire is to measure the voltage drop across it.

4. While testing variable resistors: Technician A says that while checking a rheostat with a voltmeter, the voltage should change smoothly with a change in the control.

Technician B says that a potentiometer can be checked with a scope. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A rheostat and potentiometer may be tested using a voltmeter or lab scope to observe the output voltage; look for a smooth change as the control is moved.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

5. While using an ohmmeter to measure the resistance values of a component: Technician A says that if the component has the specified resistance, the part is good.

Technician B says that having resistance does not guarantee a part is good. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Because a resistance test does not place a load on the component or circuit, it may not detect a condition where a component measures in specification when off but is out of specification under load.

6. Technician A uses a test light to test circuit protection devices. Technician B uses a voltmeter to test circuit protection devices. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Either meter may be used to test circuit protection devices.

7. Technician A uses a test light to detect high resistance. Technician B uses a jumper wire to test circuit breakers, relays, and lights. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A test light is used to identify shorted or open circuits, not to detect resistance as stated. A jumper wire can be used to bypass faulty components such as circuit breakers or relays, or to apply a known good voltage or ground supply to test a light.

8. While diagnosing the location of a wire-to-wire short: Technician A checks the wiring of the affected circuits for signs of burned insulation and melted conductors.

Technician B checks common connectors shared by the two affected circuits. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A wire-to-wire short causes increased current flow, resulting in burned insulation and melted connectors. Common connectors shared by the two affected circuits are a possible location where one circuit may be shorted to another.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

9. While measuring resistance: Technician A uses an ohmmeter to measure resistance of a component before disconnecting it from the circuit. Technician B uses a voltmeter to measure voltage drop. A circuit with very low resistance will drop zero or very little voltage. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A voltmeter is used to measure the amount of voltage dropped across a portion of a circuit. A portion of the circuit with very little resistance will drop very little of available voltage.

10. While discussing how to test a switch: Technician A says that the action of the switch can be monitored by a voltmeter. Technician B says that continuity across the switch can be checked by measuring the resistance across the switch is in its different positions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A voltmeter can be used to check a switch by testing for the presence of voltage on each side of the switch, or by performing a voltage drop test across the switch. Comparing resistance across the switch terminals as the switch is opened and closed may also be used to check it.

TECH MANUAL CONCEPT ACTIVITY 16-1 Schematic Symbols Referring to Figure 16-1, match the following schematic symbols with the correct name:

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

Figure 16–1 Identify the schematic symbols.

Answer Motor, ground, fuse, diode, SPST switch, lamp, relay, splice, transistor, circuit breaker, potentiometer

CONCEPT ACTIVITY 16-2 Test Light Diagnosis Use the diagram shown in Figure 16-2 to answer the following: 1.

If a test light were attached to the battery positive terminal and point X, would it light?

Answer Yes, it would.

2. If a test light were attached to the battery negative terminal and point Y, would it light?

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

Figure 16–2 Using a test light.

Answer Yes, it would.

CONCEPT ACTIVITY 16-3 DMM Measurement Setup Label the electrical measurement in each of the three drawings shown in Figure 16-3.

Figure 16–3 DMM setup.

Answer Voltage drop, amperage, and resistance

CONCEPT ACTIVITY 16-4 DMM Symbols Match the multimeter symbols with the correct units.

–V ~V Ω A

Amperage Resistance DC volts AC volts

Answer DC volts, AC volts, resistance, and amperage

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

CONCEPT ACTIVITY 16-5 Electrical Diagnosis Use Figures 16-4 and 16-5 to answer the questions about circuit faults.

Figure 16–4 Brake light circuit diagnosis.

1.

Based on the open at point X, what would be the symptom or customer complaint?

Answer One light would be inoperative.

2. How would you test this circuit on the vehicle?

Answer Answers will vary but may include responses such as testing for voltage with a DMM or test light.

3. What steps would you have to take to narrow down the cause of the problem?

Answer Answers will vary but may include responses such as testing at splice or connector locations until the open section is found.

4. How would the resistance at point X affect the circuit?

Answer It may cause both lights to be dim.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 16: General Electrical System Diagnostics and Service

Figure 16–5 Headlamp circuit diagnosis.

5. Would the resistance at point X affect both the right and left headlights?

Answer No, it wouldn’t.

6. Explain your answer to question 5.

Answer Each set of lights has its own power and ground sources so only the lights with the resistance in their ground path will be affected.

7. What steps would you take to diagnose this type of problem?

Answer Answers will vary but may include responses such as voltage drop tests of the power and ground circuits.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 17: BATTERIES: THEORY, DIAGNOSIS, AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 3 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 17-1 .......................................................................................................... 6 CONCEPT ACTIVITY 17-2.......................................................................................................... 6 CONCEPT ACTIVITY 17-3.......................................................................................................... 7 CONCEPT ACTIVITY 17-4 ......................................................................................................... 8

SHORT ANSWER 1.

Define an electrolyte and its role in battery operation.

Answer Electrolytes are chemical solutions that react with the metals used to construct the plates. These chemical reactions cause a lack of electrons on the positive electrode and an excess on the negative electrode. The reactions continue to provide electrons for current flow until the circuit is opened or the chemicals inside the battery become weak.

2. What design characteristics determine the voltage and the current capacity of a battery?

Answer The capacity of a battery is determined by factors such as its cell size, type of electrolyte, and type of plate materials.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

3. How is a battery leakage test conducted?

Answer To perform a battery leakage test, set a voltmeter on a low DC volt range. Connect the negative test lead to the battery’s negative terminal. Then move the meter’s positive test lead across the top and sides of the battery case. If some voltage is read on the meter, current is leaking out of the battery’s cells.

4. Describe parasitic draw.

Answer A parasitic load is an electrical load that drains the battery while the ignition is off.

Often these drains are intended to maintain computer memories or to preserve such things as clock settings and radio presets.

5. How can you identify the high-voltage system in most hybrid vehicles?

Answer The high-voltage circuit is identifiable by size and color. The cables have thicker insulation and are colored orange. The connectors are also colored orange. On some vehicles, the high-voltage cables are enclosed in an orange shielding or casing; again the orange indicates high voltage. In addition, the high-voltage battery pack battery and other high-voltage components have “High Voltage” caution labels.

6. How many volts are present in a fully charged 12-volt battery?

Answer 12.6 volts 7. What is meant by the term specific gravity?

Answer Specific gravity is the weight of a given volume of liquid divided by the weight of an equal volume of water.

8. What causes gassing in a battery?

Answer Gassing occurs in a battery during charging when the water in the electrolyte is converted into hydrogen and oxygen gases.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

9. List five things that shorten the life of a battery.

Answer Factors such as improper electrolyte levels, temperature, corrosion, overcharging, undercharging/sulfation, poor mounting, and cycling can shorten the life of a battery.

10. List five things that should be checked during a battery inspection.

Answer Open circuit voltage, the hold down, terminals, connections, battery cables, acid leaks, case condition, electrolyte level, and battery age

MULTIPLE CHOICE 1.

Which of the following statements about battery types is not true? a. Deep cycle batteries are designed to go through many charge and discharge cycles. b. A low-maintenance battery is a heavy-duty version of a normal lead-acid battery. c. Maintenance-free batteries require external holes or vent caps. d. In a gel cell battery, gassing is minimized and vents are not needed.

Answer: c. Maintenance-free batteries have small gas vent holes but not external holes or vent caps.

2. Which of the following statements about battery ratings is true? a. The ampere-hour rating is defined as the amount of steady current that a fully charged battery can supply for 1 hour at 80 °F (26.7 °C) without the cell voltage falling below a predetermined voltage. b. The cold cranking amps rating represents the number of amps that a fully charged battery can deliver at 0 °F (−17.7 °C) for 30 seconds while maintaining a voltage above 9.6 volts for a 12-volt battery. c. The cranking amp rating expresses the number of amperes a battery can deliver at 32 °F (0 °C) for 30 seconds and maintain at least 1.2 volts per cell. d. The reserve capacity rating expresses the number of amperes a fully charged battery at 80 °F (26.7 °C) can supply before the battery’s voltage falls below 10.5 volts.

Answer: c. The cranking amps rating is based on the current the battery can deliver at 32 °F (0 °C) for 30 seconds before falling below 7.2 volts.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A uses a current probe to test the open circuit voltage of a battery.

Technician B uses the results of an open circuit voltage test to determine the battery’s state of charge. Who is correct? a. Technician A b. Technician B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

c. Both A and B d. Neither A nor B Answer: b. Voltage readings from an open circuit voltage test are an indication of a battery’s state of charge.

2. Technician A says that the reserve rating of a battery is the amount of steady current that a fully charged battery can supply for 20 hours without the voltage falling below 10.5 volts. Technician B says that ampere-hour ratings state how many hours the battery is capable of supplying 25 amperes. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. The reserve capacity is the time in minutes a battery can supply 25 amps without falling below 10.5 volts at 80 °F (26.6 °C), and the ampere hour rating is the amount of steady current a fully charged battery can discharge for 20 hours at 80 °F (26.6 °C).

3. Technician A says that battery straps should be used whenever a battery is lifted.

Technician B says that when a battery is removed, the positive cable should be disconnected first. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Use a battery strap to safely lift a battery. Always remove the ground cable first, not the positive cable as stated by Technician B. 4. Technician A says jump-starting a battery can damage electronic components.

Technician B says a dead battery should be jump-started instead of recharged. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Jump-starting a battery incorrectly can cause damage to the vehicle’s electronic components.

5. Technician A says that battery corrosion is commonly caused by spilled electrolyte.

Technician B says that battery corrosion is commonly caused by electrolyte condensation from gassing. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

Answer: c. Battery corrosion is commonly caused by spilled electrolyte and electrolyte condensation from gassing.

6. Technician A says that before a battery is removed, a memory saver ought to be installed. Technician B says that before a battery is removed, the positive cable should be disconnected and the area around the battery should be cleaned. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A. A memory saver should always be installed before disconnecting or removing the battery. The battery’s negative cable should always be disconnected first.

7. Technician A says that side post terminals need to be removed to inspect them for corrosion. Technician B says that side post terminals can be damaged by overtightening the terminal bolt. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Side post terminals typically have to be removed to thoroughly inspect their condition and overtightening the fastener can strip or break the battery connection.

8. A vehicle’s battery goes dead after sitting for two days. Technician A says a thorough battery inspection should be performed. Technician B says a check for a parasitic draw should be performed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Any battery or starting system diagnosis should include a complete battery inspection. A battery that discharges in a short period of time should be checked for a parasitic draw.

9. Technician A always wears safety glasses or goggles when working with batteries.

Technician B says that there is no need to seek medical help if electrolyte gets in your eyes as long as you flush your eyes immediately after the electrolyte hits them. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

Answer: a. If electrolyte contacts your skin or eyes, flush the area with water for several minutes. When eye contact occurs, force your eyelid open and flush your eyes with eyewash solution. Do not rub your eyes or skin and call a doctor immediately.

10. While discussing the results of a load test: Technician A says that if a battery fails a load test but the voltage rises above 12.4 volts when the load is removed, the battery should be replaced. Technician B says that if a battery fails a load test but the voltage rises above 12.4 volts when the load is removed, the battery is able to hold a charge.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. If a battery fails a load test but the voltage rises above 12.4 volts when the load is removed, the battery is able to hold a charge but has insufficient cold cranking capacity and should be replaced.

TECH MANUAL CONCEPT ACTIVITY 17-1 Batteries 1.

Look around your lab and note some of the different battery-powered items and the types of batteries used in these devices.

Answer Answers will vary but may include responses such as flashlights, impacts, and jumpstarting boxes.

CONCEPT ACTIVITY 17-2 Build a Battery Batteries can be made from simple items such as vegetables, wire, and nails. To construct an organic battery, connect three potatoes, lemons, or other fruits or vegetables with pieces of copper wire. Use a galvanized nail or similar item as one battery terminal and a penny or other piece of copper for the other battery terminal. Place the end of each terminal into the organic battery. Next, connect several batteries together, positive to negative, so that you are left with the two end batteries each having an unconnected lead (Figure 17-1). Connect the voltmeter leads to the unattached leads at each end of the battery.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

1.

FIGURE 17–1 Building an organic battery.

How much voltage is produced by this battery?

Answer Answers will vary but may include 100 mV.

2. How could more voltage be produced?

Answer Answers will vary but may include responses such as increasing the number of fruits or vegetables.

3. What would be the result if the batteries were connected in parallel instead of in series?

Answer Answers will vary but may include responses such as voltage will be lower.

4. Why are the dissimilar metals needed to make the battery function?

Answer Answers will vary but may include responses such as dissimilar metals increase number in series.

5. What allows for the reaction between the metals and the vegetables or fruits?

Answer Answers will vary but may include responses such as the moisture and chemical content and the reaction to the metals.

6. What acts as the electrolyte in this battery?

Answer Answers will vary but may include responses such as the juices or moisture content.

CONCEPT ACTIVITY 17-3

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

Battery Types 1.

Examine the batteries used in lab vehicles. List the different types of batteries you find and what vehicles they are installed in.

Answer Answers will vary but may include responses such as standard flooded lead acid, enhanced flooded lead acid, AGM.

2. What are some reasons why a vehicle manufacturer may install one type of battery in one vehicle and a different type of battery in another vehicle?

Answer Answers will vary but may include reasons such as electrical system requirements, space available, etc.

CONCEPT ACTIVITY 17-4 Batteries and Temperature Obtain two flashlights that use the same size, type, and number of batteries, such as two AA or AAA powered lights. Note the time and turn on both lights. Place one light in a freezer and leave the other at room temperature. Check the lights every half hour and note their light output. Continue periodic checking until one light is out.

1.

Length of time until first light became dim: Answer Answers will vary but may include time durations such as four hours.

2. Length of time until first light went out: Answer Answers will vary but may include time durations such as 10 hours.

3. Which light became dim or went out first?

Answer Answers will vary but may include responses such as frozen flashlight.

4. If the light in the freezer went out first, how do you think the temperature affected the light?

Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 17: Batteries: Theory, Diagnosis, and Service

Answers will vary but may include responses such as the cold reduced the capacity of the batteries.

5. If you could repeat this activity with insulation on the flashlight placed in the freezer, what effect do you think the insulation would have on the results?

Answer Answers will vary but may include responses such as it will go out in less time.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 18: STARTING AND MOTOR SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 18-1 .......................................................................................................... 7 CONCEPT ACTIVITY 18-2 ......................................................................................................... 9

SHORT ANSWER 1.

Explain the purpose of the field windings in an electric motor.

Answer The field windings generate strong stationary magnetic fields.

2. Briefly explain counter EMF and how it relates to motor operation.

Answer When the armature rotates within the field windings, conditions exist to induce a voltage in the armature. Voltage is induced anytime a wire is passed through a magnetic field. When the armature, which is a structure with many loops of wire, rotates past the field windings, a small amount of voltage is induced. This voltage opposes the voltage supplied by the battery to energize the armature. As a result, less current is able to flow through the armature. The faster the armature spins, the more induced voltage is present in the armature. The more voltage induced in the armature, the more opposition there is to normal current flow to the armature. The induced voltage in the armature opposes or is counter to the battery’s voltage. This is why the induced voltage is called CEMF. 3. The part of the armature that the brushes ride on is called the ___.

Answer The part of the armature that the brushes ride on is called the commutator.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

4. Describe how to perform a starter bench test.

Answer Clamp the starter in a bench vice and connect a battery or booster to the B terminal and the starter case. Connect a remote starter switch to the S terminal and battery positive. Connect a VAT or similar tester to measure cranking amperage. Engage the starter motor and note the cranking amps. Compare the readings to specs. A motor that has a constant speed, regardless of load is called a synchronous motor.

5. List and define four components of the starting system.

Answer Answers will vary but include components such as the battery, the starter motor, batter cables, ignition and safety switches, and starter solenoid or relay. The battery provides the power to turn the starter motor. The starter motor has a drive gear that connects with the engine to spin the engine fast enough so it can start. The battery cables connect the battery to the starter and to the engine for ground. The ignition and safety switches control starter motor operation based on driver input and transmission gear position or clutch pedal position. The starter solenoid or relay completes the circuit between the battery and the starter motor.

6. Compare and contrast AC and DC motors and their operation.

Answer Answers will vary but may include responses such as most automotive DC motors are brush-type motors and AC motors are brushless. AC motors often require sophisticated electronics to control their operation.

7. List five components of a typical starter motor.

Answer The drive gear, armature, field windings or permanent magnets, brushes, kick out lever, return spring, housing, and end plate 8. Describe the three primary starting circuit voltage drop tests.

Answer Answers will vary but may include responses such as insulated power, insulated ground, and control circuit. The insulated power circuit is tested between the battery positive terminal and the motor terminal at the starter. The insulated ground circuit is tested between the battery negative terminal and the starter case. The control circuit is tested between the battery positive terminal and the control circuit or S terminal on the solenoid. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

9. Describe two causes of higher-than-normal starter current draw.

Answer Answers will vary but may include responses such as a short in the starter motor, high internal mechanical resistance in the starter, internal engine resistance.

MULTIPLE CHOICE 1.

Which of the following is not part of the starter motor circuit? a. Battery b. Starting safety switch c. Starter motor d. Relay solenoid Answer: b. The starting safety switch is part of the control circuit, not part of the high-current circuit.

2. Which of the following tests would not be performed to check for high resistance in the battery cables? a. Cranking voltage test b. Insulated circuit resistance test c. Starter relay by-pass test d. Ground circuit resistance test Answer: c. The starter relay bypass test is only used to see if the problem is related to a nonfunctioning relay. All of the other tests would determine if there was high resistance in the circuit.

3. When the starter spins but does not crank the engine, which of the following may be true? a. Defective starter relay b. Damaged flywheel teeth c. A faulty starter solenoid d. All of the above Answer: b. Damaged flywheel teeth can keep the engine from cranking even when the starter drive gear turns.

4. If the solenoid just clicks while trying to crank the engine with the starter, which of the following is not a probable cause? a. A faulty neutral safety switch b. Low battery voltage c. Low voltage available to the solenoid d. An open in the hold-in winding Answer: a. If the solenoid clicks while trying to crank the engine, the neutral safety switch is closed and would not be a probable cause of the problem.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

5. The normal minimal cranking voltage specification is approximately ___. a. 9.6 volts b. 10.5 volts c. 11.0 volts d. 12.65 volts Answer: a. There should be a minimum of 9.6 volts during cranking.

6. If a ground circuit test reveals a voltage drop of more than 0.2 volt, the problem may be ___. a. a loose starter motor mounting bolt b. a poor battery ground terminal post connector c. a damaged battery ground cable d. all of the above Answer: d. Each of these can cause an increase in ground circuit voltage drop.

7. Which of the following would not cause excessive current draw by the starter motor? a. A short in the motor b. High resistance in the armature c. Using oil that is too heavy in the engine d. Very cold weather Answer: b. High resistance in the armature or field windings causes less current draw, not more as stated.

8. The device that prevents the engine from turning the armature of the starter motor is the ___. a. overrunning clutch b. pinion gear c. flywheel d. pole shoe Answer: a. The overrunning clutch prevents the engine from turning the armature after it starts.

9. A control circuit voltage drop test shows a 1.1 volt drop at the starter S terminal.

Which of the following could be the cause? a. High resistance in the solenoid switch circuit b. High resistance in the clutch safety switch c. Loose battery cable connection d. Short in the starter armature windings Answer: a. High resistance in the solenoid control circuit may cause an excessive voltage drop to the S terminal.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

ASE-STYLE REVIEW QUESTIONS 1.

An engine cranks slowly: Technician A says that a possible cause of the problem is poor starter circuit connections. Technician B says that an engine problem could be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Corroded connections and engine problems can cause the engine to crank slowly.

2. While discussing auto start-stop systems: Technician A says special starters are used that allow for quicker engine restarts. Technician B says both the starters and generators are different on vehicles with this system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. The starters are more robust to allow for more frequent starts, and the solenoid is different to provide cranking even when the engine is spinning down. The generator on auto start-stop systems are the same as on other vehicles.

3. Pinion gear-to-flywheel ring gear clearance is being discussed: Technician A says that if there is too much clearance, there will be a high pitch whine while the engine cranks. Technician B says that if there is too little clearance, there will be a high pitch noise after the engine is started. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. If clearance is excessive, the starter will produce a high-pitched whine while cranking, not after the engine starts, as stated by Technician A. If clearance is insufficient, there will be a high-pitched whine after the engine starts, as stated by Technician B. 4. Technician A says that a starter no-load test is conducted with the starter in a bench vise. Technician B says that the no-load test is used to determine starter motor circuit voltage drop. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. The open circuit voltage test checks the available voltage at the battery.

The no-load test is used to check the voltage drop of the starter motor circuit.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

5. Cranking current is excessive but is normal when the starter is bench tested: Technician A says the problem could be with the positive battery connection to the solenoid. Technician B says there could be an engine mechanical problem. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A problem with the positive battery connection will likely cause excessive voltage drop and decrease current flow. A mechanical problem with the engine that prevents it from spinning easily will increase current flow.

6. Technician A says that the purpose of the starter relay is to complete the circuit from the battery to the starter motor. Technician B says that the purpose of the solenoid is to complete the circuit from the battery to the starter motor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Either a relay, a solenoid, or both may be used to complete the circuit from the battery to the starter motor.

7. When diagnosing a no-crank no-start condition, no voltage is present at the S terminal of the solenoid while attempting to crank the engine. Technician A says a faulty starter motor is the cause. Technician B says a shorted safety switch is the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. No power to the S terminal would be caused by an open in the control circuit.

8. While discussing a no-crank condition: Technician A says to verify the condition of the battery before testing the starter motor. Technician B says a scan tool may be used to check starter control circuit operation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The battery condition should always be checked and a scan tool may be used to determine if the cranking circuit is operating.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

9. While discussing DC starting motors: Technician A says that the armature may be wired in series with the field coils. Technician B says that the field coils may be wired parallel with the armature. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. The armature may be wired in series with the field coils (series motor); the field coils may be wired parallel or shunted across the armature (shunt motors); or a combination of series and shunt wiring (compound motors) may be used.

10. While discussing electric motors: Technician A says that when there is high CEMF, there will be high current flow. Technician B says that if the reluctance of an electromagnet increases, its field strength increases. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Current will decrease with an increase in CEMF. Also, if the reluctance increases, the magnet’s field strength will decrease.

TECH MANUAL CONCEPT ACTIVITY 18-1 Magnetic Fields Obtain several magnets from your instructor. Round magnets with a hole in the center are preferred; transmission oil pan magnets work well. Place a pencil through the magnets.

Arrange the magnets so they are repulsing each other.

1.

How many magnets can you place over the pencil without the magnets touching each other?

Answer Answers will vary but may include numbers such as four or five.

2. Approximately how far apart do the magnetic fields keep each magnet separated?

Answer Answers will vary but may include 1/8”.

Next, take two or three of the magnets from the pencil and place them on a wooden (non-magnetic) bench top. Arrange the magnets so that they are near each other, but not in contact. Use the magnet’s repulsion to move a second magnet.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

3. How close do the magnets have to be for the magnetic repulsion to cause movement?

Answer Answers will vary but may include ¼”.

Join two magnets together and attempt to move a third magnet.

4. How did using two magnets affect the distance necessary to move the third?

Answer Answers will vary but may include responses such as it decreases the distance.

Now, move two magnets close together so that they attract each other. Be careful not to pinch your fingers.

5. How close can the magnets get before the magnetic attraction brings them together?

Answer Answers will vary but may include 1/8”.

6. How does this distance compare to the distance for magnetic repulsion?

Answer Answers will vary based on magnetic field but should be similar.

Place a magnet upright on its edge. Next, try to position two additional magnets near the first magnet and attempt to make the upright magnet rotate or move.

7. Describe what happens when trying to get the magnet to rotate.

Answer Answers will vary but may include responses such as it only moves slightly.

8. What do you think would be necessary to make one magnet rotate in response to two other magnets placed in close proximity?

Answer Answers will vary but may include responses such as additional magnetic fields and a way to support the spinning magnet.

9. Describe your conclusions about magnetic attraction and repulsion.

Answer Answers will vary but may include responses such as magnetic fields can create motion.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

CONCEPT ACTIVITY 18-2 Toy Motor Building Obtain from your instructor two transmission pan-type magnets, a two- to three-foot length of insulated single-strand wire like that used for armature windings on a fan motor, paper clips or cotter pins, a Styrofoam cup or small box, and a 9-volt battery. Follow these steps to build a simple DC electric motor: •

Strip the ends of the wire to remove about one-half of the insulation along the length of the last 2 inches of the wire. Each end should have bare copper exposed around half of the wire’s circumference and insulation around the other half. This will allow an on-off connection through the wire.

•

Form the wire (coil) into a tightly wound loop approximately 1 inch in diameter, leaving the two ends protruding out from the middle (Figure 18-1).

FIGURE 18–1 A tightly wound loop of wire.

•

Mount the paper clips or cotter pins into the cup or box so that they can form a holding fixture for the wire.

•

Place the magnets so that they hold each other to the top section of the cup or box between the paper clips or cotter pins.

•

Place the wire into the paper clips or cotter pins. Adjust the height so that the coil can rotate very close to the magnet without touching.

•

Attach the 9-volt battery so that the positive is connected to one paper clip or cotter pin, and the negative is connected to the other paper clip or cotter pin (Figure 18-2).

•

Some adjusting may be required, but once a good connection is made, the coil should easily spin on its own.

FIGURE 18–2 A simple DC motor.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

1.

Note the coil’s direction of rotation.

Answer Answers will vary but may include responses such as clockwise or counter-clockwise.

2. Reverse the battery polarity and note the motor rotation.

Answer Answers will vary.

3. Why did the motor respond as it did to the battery voltage change in polarity?

Answer Answers will vary but may include responses such as it reversed the polarity of the magnetic field.

4. List the electrical motors used in modern automobiles that operate so that they reverse their direction of rotation.

Answer Answers will vary but may include responses such as power window motors, power door lock motors, power moonroof motors, power seat motors.

5. List the electrical motors used in modern automobiles that rotate in only one direction.

Answer Answers will vary but may include responses such as cooling fan motors, interior fan motors, CD/DVD player motors.

6. What would be the result if a motor, such as for the cooling fan that only rotates one way, were hooked to the battery in reverse polarity?

Answer It would rotate in reverse.

7. Match the motor components with their electrical function.

Paper clip or cotter pin Armature Wire Brush Magnets Commutator Wire insulation Field coils

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10

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 18: Starting and Motor Systems

Answer paperclip/cotter pin = brush Wire = armature Magnets = field coils Wire insulation = commutator 8. Explain why the wire’s insulation is not completely removed.

Answer To provide a break in the circuit to allow for the switching magnetic field 9. What effect would the use of a smaller battery, such as a D cell, have on the motor, and why?

Answer The rotation speed would be reduced due to less voltage.

10. How would the use of more magnets affect the operation of the motor, and why?

Answer It may increase the speed and/or torque.

11. Why do you think the electric motors used in automobiles have more commutator segments than the simple motor you built?

Answer This is because of greater speed and/or torque requirements.

12. What are the wear points on a DC motor?

Answer Brushes and commutator 13. What are some examples of problems that can affect the operation of a DC motor?

Answer Answers will vary but may include responses such as circuit resistance, mechanical binding.

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11

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 19: CHARGING SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 19-1 .......................................................................................................... 6 CONCEPT ACTIVITY 19-2 ......................................................................................................... 8

SHORT ANSWER 1.

What is the purpose of the diodes in the generator?

Answer The diodes allow or block current flow based on how they are configured. This is to change the AC current into DC current.

2. How does a voltage regulator regulate the voltage output of an AC generator?

Answer The voltage regulator regulates the voltage output of an AC generator by controlling the amount of current through the rotor, which changes its magnetic field strength.

3. Describe the differences between an overrunning alternator pulley and an alternator decoupler pulley.

Answer Overrunning pulleys reduce noise and vibration by allowing the generator drive to coast when engine speed decreases. Decoupling pulleys have an additional spring to absorb torsional vibrations without affecting generator speed.

4. What would happen to the output of an AC generator if one of the stator windings has an open?

Answer The output would be reduced by about a third.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

5. Describe the basic difference between a DC motor and a DC generator.

Answer In a motor, the armature receives current from a power source. This creates the magnetic field that opposes the magnetic fields in the motor’s coils, which causes the armature to rotate. The armature in a DC generator is driven by the engine or other device. It is not magnetized, and the windings simply rotate through the stationary magnetic field of the field windings. This induces an AC voltage in the conductors inside the armature.

6. Explain how to perform charging system voltage drop tests.

Answer Answers will vary but may include the following responses: Connect the positive DMM lead to the generator output terminal and the DMM negative lead to the battery positive terminal. Connect the positive DMM lead to the battery negative and the negative DMM lead to the generator case.

7. Explain the differences between a wye and a delta stator winding.

Answer A wye winding is shaped like a Y and is used for higher charging rates at low speeds. A delta winding resembles the Greek letter delta and is used for high charging rates at high speeds.

8. Explain the voltage regulator A and B circuits.

Answer An A circuit has the regulator on the ground side of the field, and a B circuit places the regulator on the power side of field.

MULTIPLE CHOICE 1.

A rotating magnetic field inside a set of conducting wires is a simple description of a ___. a. DC generator b. AC generator c. voltage regulator d. none of the above Answer: b. AC generators have rotating magnetic fields inside a set of conductors.

2. What part of the AC generator is the rotating magnetic field? a. Stator b. Rotor © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

c. Brushes d. Poles Answer: b. The rotor is the rotating magnetic field consisting of a field coil around an iron core and two sets of pole pieces. As current flows through the coil, the core is magnetized and the pole pieces assume the polarity of the end of the core that they touch.

3. Which type of stator winding has two windings in parallel? a. Wye b. Delta c. Trio d. Series Answer: a. The wye winding 4. Slip rings and brushes ___. a. mount on the rotor shaft b. conduct current to the rotor field coils c. are insulated from each other and the rotor shaft d. all of the above Answer: d. The slip rings and brushes are located on the rotor shaft, conduct current to the field coil, and are insulated from each other.

5. The alternating current produced by the AC generator is rectified into DC, or direct current, through the use of ___. a. transistors b. electromagnetic relays c. diodes d. capacitors Answer: c. AC current is rectified into DC through the use of diodes.

6. A voltage drop over ___ indicates high resistance in either the positive or ground circuit of the charging system. a. 0.1 volt b. 0.2 volt c. 0.5 volt d. 1.0 volt Answer: c. If a voltage drop of over 0.5 volt is found in either circuit, there is high resistance in that circuit.

7. Voltage regulation by a PCM is done by ___. a. using a variable resistor to vary current flow to the rotor field windings b. pulsing current flow to the rotor field windings on and off to create a correct average field current supply c. changing the duty cycle of a current sensor to control the field’s path to ground d. none of the above

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

Answer: b. When computer modules control voltage regulation circuits, they pulse current flow through the field windings, varying the amount of on time to achieve precise voltage regulation.

8. Current flow to the rotor is controlled by which of the following? a. Diodes b. Stator c. Voltage regulator d. Pole pieces Answer: c. Field current is controlled by the voltage regulator.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that the waveform produced by an AC generator after rectification is called a sine wave. Technician B says that the waveform produced by the AC generator after the output moves through the diodes is a straight line because it is a constant DC voltage. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The waveform produced by an AC generator, before rectification, is called a sine wave. After one complete rotation of the rotor, the waveform is comprised of three staggered sine waves. The waveform produced after the output moves through the diodes is not a straight line, but a rippled line whose shape resembles the rounded tops of a picket fence.

2. While discussing what is indicated by a vehicle’s charge indicator: Technician A says that any positive reading on an ammeter shows that the generator is in working condition. Technician B says that if the voltmeter reading does not increase immediately after starting the engine, the battery is bad. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A positive indication on the ammeter indicates the generator is working.

3. When checking the charging system on a late-model vehicle: Technician A connects a scan tool to monitor the system’s voltage output. Technician B connects a scan tool to retrieve any DTCs that may be in the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

Answer: c. On PCM-controlled systems, diagnosis should include a check for diagnostic trouble codes (DTCs). Also, on most systems, the voltage output can be monitored with a scan tool.

4. While diagnosing the cause of a noise coming from a generator just after the engine shuts off: Technician A says that the noise can be caused by something mechanical or electrical. Technician B says that the whirring noise is probably caused by a diode or an overrunning clutch and it should be considered normal. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. If there is noise coming from the AC generator after the engine has been shut down, the cause must be something mechanical such as the overrunning clutch.

This clutch may cause a noise as it slows down, and this is normal.

5. Technician A says generator output should be within 10 amps of the AC generator’s rated output. Technician B says generator voltage output should not exceed 14.5 volts during voltage output test. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Generator output should be within 10 percent of its rated output and voltage should not exceed 14.5 volts under load.

6. Technician A says that many newer charging systems do not have a separate voltage regulator. Technician B says that most late-model charging systems are computer regulated through the ground of the field. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Many modern charging systems use the engine control module to regulate generator output.

7. While diagnosing rapid and severe belt wear after generator replacement: Technician A says that a defective drive belt tensioner may be the cause. Technician B says that the generator may have the wrong type of pulley installed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. A worn belt tensioner or incorrect drive pulley could cause rapid belt wear.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

8. Technician A says that if there was no output from the charging system until the AC generator was full-fielded, the voltage regulator is faulty. Technician B says that this indicates one or more leaking diodes in the generator. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. If there is no output until the AC generator is full-fielded, the voltage regulator is faulty. One or more leaking diodes would reduce output.

9. When checking AC generator output on a late-model vehicle: Technician A tests the battery’s open circuit voltage before testing the generator’s output because the battery’s SOC will affect the maximum output of the generator. Technician B checks the ambient temperature before performing any tests because the generator’s output will be affected by temperature. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Several conditions will cause the PCM to increase or decrease the target charging output. These include the current operation of some heavy current draw accessories, the battery’s state-of-charge, low current demand at constant vehicle speeds, low speed after initial engine start-up, and low or high temperatures.

10. While testing a charging system: Technician A says that an overcharge condition is evident any time charging voltage is greater than 13 volts. Technician B says that the system should be able to supply its maximum current output when the engine is at idle and there is no load on the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither is correct. A voltage reading of over 16-volts indicates an overcharging problem, 13-volts is rather low. Maximum output can only be expected when there is a heavy load on the generator and when the engine is running at a moderate speed.

TECH MANUAL CONCEPT ACTIVITY 19-1 Inducing Voltage Obtain a bar or cylindrical magnet and a length of wire from your instructor. Attach the leads of a DMM to the ends of the wire. Set the DMM to read AC voltage. Next, move the magnet so

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

that the lines of force from the north to south poles cut across the wire. Move the magnet quickly back and forth as close to the wire as you can.

1.

How much voltage did the DMM read?

Answer Answers will vary but may include ranges such as 10–100 mV.

2. Move the magnet across the wire more slowly than before. How much voltage was generated?

Answer Answers will vary but may include ranges such as 10–20 mV. 3. Move the magnet so that the north and south poles move parallel with the wire. How much voltage was generated?

Answer Answers will vary but may include responses such as no voltage reading.

Next, obtain two permanent magnet-type wheel speed sensors or crank/cam position sensors. Attach the leads of the DMM to one of the sensors. Next, move the sensing tip of the second sensor quickly back and forth very close to the sensing tip of the first sensor.

4. How much voltage did the DMM read?

Answer Answers will vary but may include ranges such as 10–100 mV. 5. Was the voltage generated by the sensors greater than the voltage generated by the single magnet and piece of wire?

Answer Answers will vary but may include responses such as yes or no.

6. If the voltage was greater, why do you think that was so?

Answer Answers will vary but may include responses such as increased wire or proximity.

7. What conclusions can you make about induced voltage?

Answer Answers will vary but may include responses such as voltage is based on proximity, strength of magnetic fields, and the number of conductors.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 19: Charging Systems

CONCEPT ACTIVITY 19-2 Generator Components Match the following generator components with their function.

Diode Coil Fan Voltage regulator Stator Slip ring

Generates magnetic field Supplies power to the coil Converts AC into DC Has induced AC current Removes heat Connection for brushes

Answer Diodes = converts AC to DC Coil = generates magnetic field Fan = removes heat Voltage regulator = supplies power to the coil Stator = has induced AC current Slip rings = connection for brushes

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8

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 20: LIGHTING SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 20-1 ......................................................................................................... 6 CONCEPT ACTIVITY 20-2......................................................................................................... 8 CONCEPT ACTIVITY 20-3........................................................................................................ 10 CONCEPT ACTIVITY 20-4........................................................................................................ 12

SHORT ANSWER 1.

What lighting systems are controlled by the headlight switch?

Answer The headlamp switch controls the headlights, parking lights, side markers, taillights, license plate light, and instrument panel lights.

2. What is a CHMSL? Answer A center high mount stop light.

3. How many wires are normally connected to a double-filament light bulb?

Answer Double-filament bulbs have two hot wires. Some are grounded through their case and others require a third, ground wire.

4. What are the most probable causes for one low-beam headlamp not working?

Answer A bad bulb or high resistance in the power or ground circuit. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

5. Why do some manufacturers protect the headlamp circuit with a circuit breaker instead of a fuse?

Answer The use of a circuit breaker to protect the headlight circuit allows for illumination of the headlights part of the time when there is a problem.

6. What types of headlights do not have a filament?

Answer High-intensity discharge (HID) lights do not have a filament; instead, an electric arc is created between two electrodes that excite a gas, such as xenon, inside the headlamp.

LED lamps also do not rely on a filament; they are semiconductors that give off light as current passes through them.

7. What is the primary tool used to diagnose an auto-leveling headlamp system?

Answer Diagnosis of this system is mostly done with a scan tool 8. Explain why you should not touch the glass of a halogen bulb.

Answer Touching the glass deposits dirt and oil from your skin onto the glass, which can reduce bulb life.

9. List three circuits that may be controlled by a multifunction switch.

Answer Headlights (low and high beam), horn, wipers, turn signals, hazard lights 10. Describe the safety precautions you should take when servicing high-intensity discharge lamps.

Answer Follow the service procedures exactly, and let the voltage dissipate before service.

11. List four types of lighting found on modern vehicles.

Answer Incandescent, LED, HID, Xenon, halogen, neon, and fluorescent

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

MULTIPLE CHOICE 1.

Which of the following may cause the turn signal blink rate to be incorrect? a. Burned out bulb b. Open in turn signal circuit c. Incorrect flasher unit installed d. All of the above Answer: d. All of the choices could cause an incorrect blink rate.

2. Circuits that can energize the high beams even if the headlight switch is off are known as ___ circuits. a. flash-to-pass b. mercury c. dimmer d. retractable Answer: a. The flash-to-pass feature illuminates the headlights even when the switch is in the off position.

3. Which of the following would probably not cause the headlights on both sides of the vehicle not to work? a. An open in the power or ground circuit b. A bad headlight switch c. A blown fuse d. Low generator output Answer: d. Unless the battery was totally dead, the headlights would still come on.

They may be dim, but they would illuminate.

4. The stoplight switch is normally mounted on the ___. a. instrument panel b. transmission c. brake pedal arm d. none of the above Answer: c. The stoplight switch is normally mounted on the brake pedal arm.

5. Which of the following is not a true statement about LED-based lights? a. LEDs achieve their full output in about 200 milliseconds. b. LEDs require a much smaller space so they are much less intrusive in the trunk. c. LEDs have a long operating life. d. LEDs provide a more precise contrast and signal pattern, thus attracting attention much more effectively.

Answer: a. LEDs achieve their full output in less than 1 millisecond, not 200 milliseconds as stated.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

6. One turn signal indicator blinks normally, while the other indicator blinks very rapidly.

Which of the following is the most likely cause? a. Faulty flasher unit b. Shorted turn signal switch c. Open brake light switch connection d. Inoperative bulb Answer: d. The most common cause for incorrect turn signal blink rate is an inoperative bulb.

ASE-STYLE REVIEW QUESTIONS 1.

While troubleshooting a headlight problem: Technician A says that when one headlamp does not work, the problem may be a burned-out bulb or lamp. Technician B says that you should check for voltage at the bulb before replacing a bulb. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. When one headlamp does not work, the problem is often a burned out bulb; check for the presence of voltage, and if voltage is present, replace the bulb.

2. Technician A says that the condition of the vehicle’s springs and shocks should be checked before aligning a headlight. Technician B says that the vehicle should have a full tank of fuel when its headlights are being adjusted. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Before adjusting the headlights, check the condition of the springs and shocks, and make sure the fuel tank is at least half full, not full as stated by Technician B. 3. Composite headlights are being discussed: Technician A says that they have replaceable bulbs. Technician B says that condensation on the lens will prevent the operation of a composite headlamp. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Composite lights have a replaceable bulb, but condensation buildup on the lens will not prevent operation as stated by Technician B.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

4. While troubleshooting a brake light problem: Technician A says that when the pedal is depressed the brake lights should come on. Technician B says that on some systems only part of the brake light should illuminate when there is slight pressure on the brake pedal. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. When the brake pedal is partially depressed, the brake lights should illuminate; a vehicle equipped with adaptive brake lights will illuminate the standard brake lights during moderate braking, and under intense or ABS-controlled braking, additional lamps are illuminated.

5. Technician A says that a composite headlight housing that is cloudy should be replaced. Technician B says that clouding or oxidizing of the composite housing or lens may be removed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The oxidation may be able to be removed and the housing polished.

6. While diagnosing an HID lamp that does not turn on: Technician A says a smoky or blackened lamp may indicate the bulb is burned out. Technician B says before replacing a suspected bad ballast, check to make sure it is getting power and ground.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. When a HID lamp is not working, do not automatically assume there is a faulty lamp. The ballast assembly could be bad or there is a fault in its electrical circuit. To make sure the circuit is operating fine, check for battery voltage at ballast and also check its ground. Look at the lamp; a smoky or blackened lamp may indicate the bulb is burned out. If the bulb looks good, but does not illuminate, it is likely that the ballast or igniter is faulty.

7. Technician A says that flickering vehicle lights can be caused by a circuit breaker that is kicking in and out due to a short. Technician B says that flickering vehicle lights can be caused by a loose electrical connection. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Flickering lights can be caused by a faulty circuit breaker or a loose connection.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

8. The turn signals operate in the left direction only: Technician A says that the flasher unit is bad. Technician B says that the fuse is probably blown. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Both are wrong. If either of these were the problem, all turn signals would not work. The problem is something that is common to only the left side.

9. The right back-up lamp is dim: Technician A says that the back-up lamp switch may have high resistance. Technician B says that the back-up lamp fuse may have corroded terminals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Both are wrong. If either of these were the problem, both back-up lamps would be dim. The problem is something that is common to only the right side.

10. When the headlights are switched from low beam to high beam, all headlights go out: Technician A says that the problem may be a bad dimmer switch. Technician B says that the ignition switch may be bad. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician B is wrong because the ignition switch would affect all circuits.

The dimmer switch, however, is the control for both the low and high beams. If it were bad, either or both beams may not work.

TECH MANUAL CONCEPT ACTIVITY 20-1 Lighting Principles Incandescent lights use a thin wire filament, which, when current passes through it, gets hot enough to glow and radiate light. This type of lightbulb has been in use since Thomas Edison developed it in 1879.

1.

How does the material of the filament affect a lightbulb’s operation?

Answer It affects electrical resistance, current flow, brightness, power consumption, and service life.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

2. Why is the filament enclosed in a vacuum?

Answer The filament is enclosed in a vacuum so that oxygen in the air does not combust with the hot filament.

3. How will breaking the vacuum seal affect the bulb’s operation?

Answer The filament will burn up quickly.

Incandescent lights have been in use for well over one hundred years, but they are now being replaced in automotive applications by other types of lighting.

Light-emitting diodes (LEDs) are solid-state devices that produce light with very little heat while using very small amounts of electricity.

4. Explain what a standard diode is and describe its function.

Answer An electrical one-way valve that due to its structure will allow current to flow in one direction but not the other under normal conditions.

5. Describe how light is produced by LEDs. Answer When an electron moves to a lower energy level in a hole, it emits a photon of energy.

6. Explain why electrical power conservation is important in modern automobiles.

Answer Reduced power consumption means smaller wiring, which saves weight and construction costs; hybrids and electric vehicles that conserve power in accessories can use the power for propulsion.

High-intensity discharge (HID) lights are available on many vehicles. They provide better illumination than standard bulbs but operate much differently than incandescent or LED bulbs.

7. Explain the basic operation of HID lights.

Answer HID lights use a high voltage arc to produce light.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

8. Why do HID lights require high voltages to operate?

Answer HID lights require high voltages to operate to maintain the current flow and arc across the electrodes.

9. What are the symptoms of an HID light in the beginning stages of failure?

Answer Cycling on/off 10. What service and safety precautions must be observed when working in HID lighting systems?

Answer One must exercise caution with the transformers due to the high voltages produced for start-up and operation.

CONCEPT ACTIVITY 20-2 Lighting Identification Referring to the following figures, identify the automotive lights.

Answer Sealed beam headlight

Answer Replaceable halogen insert bulb

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

Answer 3157 taillight/stoplight bulb

Answer Single filament taillight bulb

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

Answer Single filament 163/194 bulb, interior and exterior lights

Answer HID lights

Answer LED taillight

CONCEPT ACTIVITY 20-3 Electrical Circuits To diagnose a malfunctioning lighting circuit, it is necessary to have the ability to read and understand an electrical wiring diagram. Trace the current flow through the low-beam portion of the circuit shown in Figure 20-1 below.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

FIGURE 20–1 A typical headlamp circuit.

Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 20: Lighting Systems

CONCEPT ACTIVITY 20-4 Electrical Circuit Diagnosis 1.

What would be the symptom(s) if there were high resistance at point X in the diagram below?

Answer Dim or inoperative low beam lights 2. List the steps you would take to diagnose this condition.

Answer Answers will vary but may include responses such as voltage drop tests.

3. What tools might be needed to diagnose and repair this concern?

Answer Answers will vary but may include responses such as DMM and test light.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 21: INSTRUMENTATION AND INFORMATION DISPLAYS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 21-1 .......................................................................................................... 6 CONCEPT ACTIVITY 21-2.......................................................................................................... 7

SHORT ANSWER 1. Explain how an air-core gauge works.

Answer An air-core gauge relies on the interaction of two electromagnets and the effect of the strength of those fields on a permanent magnet. The needle of the gauge is attached to the permanent magnet. The electromagnetic windings do not have a metal core; rather the permanent magnet is placed inside the windings. One of these windings is a reference winding and receives battery voltage at all times. The other winding, called the field winding, is placed at angle to the reference winding. When current flows through the coils, their magnetic fields superimpose and the magnet is free to align with the combined fields. The amount of movement is controlled by the resistance of the sending unit.

2. What are two ways to provide input for the speedometer?

Answer Input to a speedometer is provided by a speedometer cable from the transmission, from a vehicle speed sensor to the speedometer head, or through wheel speed sensor inputs to the instrument cluster.

3. Describe the two types of instrument panel displays.

Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

The two types of instrument panel displays are analog and digital.

4. What is the device found in some fuel tanks to prevent fuel gauge fluctuations due to rough road surfaces?

Answer An anti-slosh/low fuel warning (LFW) module in the fuel tank reduces needle fluctuation caused by the motion of the fuel in the tank and also provides a warning when fuel level is about 1/8 full.

5. What is the correct way to check a coolant temperature sensor?

Answer A coolant temperature sensor is tested by measuring resistance between its terminal and ground. It should change in response to changing engine temperature, and the results should be within specifications.

6. What type of sending unit is typically used to monitor oil pressure?

Answer Oil pressure gauges typically use a piezoresistive sensor in the sending unit.

7. What is the major difference between an indicator lamp and a warning light?

Answer Indicator lamps are used to indicate when something is turned on; warning lights are used to notify the driver that something in the system is not functioning properly.

8. Which two devices trigger the warning and indicator lamps?

Answer Normally open or normally closed switches.

9. Explain how a fuel gauge and sending unit display fuel level.

Answer The fuel sender is a variable resistor that controls the current flow through the gauge.

As fuel level changes, the resistance increases or decreases, changing the current flow through the gauge.

10. Explain the function of a balancing coil gauge.

Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

Answers will vary but may include: The current flowing through the two or three coils causes the needle to move toward the stronger magnetic field.

MULTIPLE CHOICE 1.

The indicator needle on a speedometer is held to the zero position by ___. a. magnetic force b. the weight of the needle c. the speedometer cable d. a hairspring Answer: d. The indicator needle of a cable-driven speedometer is held in the zero position by a hairspring.

2. Which of the following uses a permanent magnet and two electromagnets? a. Air-core gauge b. Balancing coil gauge c. Quartz analog gauge d. D’Arsonval gauge Answer: b. A balancing coil gauge relies on two electromagnets and a permanent magnet to move the gauge’s needle.

3. What type of memory is used to store the accumulated mileage in an electronic odometer? a. RAM b. ROM c. PROM d. None of the above Answer: d. Accumulated mileage is stored in nonvolatile ROM so that the mileage value is retained even when the battery is disconnected.

4. Which of the following is not a true statement about lamp-out warning lights? a. The lamp-out warning module measures small changes in voltage levels. b. An electronic switch in the module completes a ground path for the indicator lights in the event of a bulb going out. c. A special resistance wire is used in multibulb systems. d. When a bulb burns out, the module senses the increased voltage drop and turns on the indicator lamp.

Answer: d. The module senses a decreased, not an increased, voltage signal when one bulb is burned out.

5. Which of the following statements about oil gauge circuits is not true? a. A switch can be used. b. A thermistor can be used. c. A piezoresistive sensor can be used. d. An oil pressure gauge may not show actual oil pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

Answer: b. A thermistor reacts only to temperature changes and not to pressure.

ASE-STYLE REVIEW QUESTIONS 1.

While discussing what the maintenance reminders base the time for the next service on: Technician A says that future service is based on the type of driving the vehicle has seen since the last service. Technician B says that the next interval may be based only on the number of miles or kilometers since the last service. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The service interval display may be based only on distance traveled. On many vehicles, driving style and previous operating conditions are also included in its calculations.

2. None of the engine’s gauges works: Technician A tests gauge operation using a scan tool.

Technician B begins by checking the fuse and then checks for voltage at the last point common to all the malfunctioning gauges. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. These are among the tests that should be conducted when all of the gauges are malfunctioning.

3. The oil pressure light stays on whenever the engine is running, and the oil pressure has been checked and it meets specifications: Technician A says that a ground in the circuit between the indicator light and the pressure switch could be the cause. Technician B says that an open in the pressure switch could be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A pressure-actuated switch in the sending unit controls the oil pressure light. It provides a ground when there is no oil pressure and opens when there is sufficient oil pressure. A ground in the circuit between the indicator light and the pressure switch would turn the light on. An open circuit would turn the light off.

4. A digital speedometer constantly reads 0 mph: Technician A says that the problem may be the vehicle speed sensor. Technician B says that the problem may be the throttle position sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

Answer: a. Digital speedometers receive input from the vehicle speed sensor, not the throttle position sensor.

5. All gauges operate but read lower than normal: Technician A says that the connection to the instrument cluster may be corroded. Technician B says that the cluster’s IVR may be open. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. When there is a corroded connection to the instrument cluster, it could cause all of the gauges to read too low. An open in the IVR would more likely cause the gauges that are dependent on it for their voltage source to not operate at all.

6. When testing an engine temperature sensor: Technician A uses an ohmmeter to test the thermistor. Technician B says that the thermistor reacts to pressure and applies air pressure to the backside of the sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Measuring the resistance of a thermistor is a valid test since it changes resistance in proportion to temperature. A thermistor reacts only to temperature, not pressure so Technician B is wrong.

7. The coolant temperature gauge stays low (cold) after the engine has been started and ran until the engine is hot: Technician A says that the wires to the sending unit may be shorted together. Technician B says that the sending unit may be electrically open. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. If the sending unit or the wire from it were open, the lamp could not light.

If the wires were shorted together, it would have the same result as a very hot engine.

8. While discussing the instrumentation on a Toyota hybrid: Technician A says that the “ready” light must be on before the vehicle is able to move. Technician B says that the engine must be running before the “ready” light is turned on. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. When the car is ready to be driven, the engine may not be running, but the “ready” lamp will be lit, which means the motor is ready to move the vehicle. If the “ready lamp” does not come on, the vehicle cannot be driven.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

9. The TPM warning lamp is lit: Technician A says that the cause could be low inflation.

Technician B says that the customer may have used a tire sealant to seal a puncture.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The TPM lamp will illuminate whenever the tire pressure is low or when the sensor is unable to communicate with the receiver, which could be caused by tire sealant blocking the air port at the sensor.

10. The yellow electronic throttle control warning lamp comes on occasionally while the vehicle is driven: Technician A says that this means there is a problem with the system.

Technician B says that the system is actively regulating drive torque and engine power when the lamp is lit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. This lamp is illuminated only when the PCM sees a problem within the control system. When the lamp is lit, the system moves into a safe mode.

TECH MANUAL CONCEPT ACTIVITY 21-1 Warning Light Identification Obtain the keys to a vehicle from your instructor. Note the vehicle information: Year ________________ Make _________________________ Model __________________

1.

Turn the key to the ON position and note the warning lights on the IP. Answer Answers will vary but include: brake, check engine, TPMS, battery, oil, seatbelt, or air bag

2. Are there any spots on the IP for lights where none illuminates?

Answer Answers will vary but include: yes or no

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

Locate a wiring diagram for the IP. Locate the warning lights that are controlled by a switch and those that are computer-controlled.

3. Switch-operated warning lights Answer Answers will vary but include: door ajar or oil pressure 4. Computer-controlled warning lights Answer Answers will vary but include: fuel level, battery, or TPMS

CONCEPT ACTIVITY 21-2 Coolant Temperature Sensors Obtain from your instructor a sample of coolant temperature sensors. Measure the resistance of the sensors at room temperature.

1. Sensor 1 resistance, cold __________ Answer Answers will vary but include: 50–100k ohms 2. Sensor 2 resistance, cold __________ Answer Answers will vary but include: 50–100k ohms 3. Sensor 3 resistance, cold __________ Answer Answers will vary but include: 50–100k ohms Next, carefully heat the sensors and recheck their resistance. Do NOT use a flame to heat the sensors.

1.

Sensor 1 resistance, hot __________ Answer Answers will vary but include: 50–100 ohms

2. Sensor 2 resistance, hot __________ Answer Answers will vary but include: 50–100 ohms

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 21: Instrumentation and Information Displays

3. Sensor 3 resistance, hot __________ Answer Answers will vary but include: 50–100 ohms 4. How did the increase in temperature affect the sensors’ resistance?

Answer Answers will vary but include: resistance goes down as temperature goes up Fuel sending units use variable resistors to change the voltage for the dash fuel gauge.

Voltage is supplied to the sending unit. The voltage returned depends on the position of the fuel float level, which is attached to the variable resistor.

Ask your instructor for an old fuel sending unit.

5. Measure and note the resistance of the sensor with the float at the fully raised position.

Answer Answers will vary but include: 200 ohms 6. Measure and note the resistance of the sensor with the float at the fully lowered position.

Answer Answers will vary but include: 40 ohms 7. How would unwanted resistance affect the coolant temperature and fuel level circuits?

Answer Unwanted resistance will change the readings displayed by the coolant and fuel gauges.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 22: BASICS OF ELECTRONICS AND COMPUTER SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 3 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 22-1 ......................................................................................................... 6

SHORT ANSWER 1.

Explain the three types of memory used in the computer system.

Answer The three main types of memory in a computer are called, ROM, RAM, and PROM. Read-Only Memory (ROM). Permanent information is stored in read-only memory (ROM). Information in the ROM cannot be erased, even if the system is turned off or the CPU is disconnected from the battery. As the name implies, information can only be read from ROM. Programmable Read-Only Memory (PROM). The programmable read-only memory (PROM) differs from the ROM in that it plugs into the computer. It contains program information specific to different vehicle model calibrations. The PROM in some computers is replaceable or reprogrammable, to upgrade the system.

Random-Access Memory (RAM). The random-access memory (RAM) is used during computer operation to store temporary information. The CPU can write, read, and erase information from RAM in any order, which is why it is called random. One characteristic of the RAM is that when the ignition key is turned off and the engine is stopped, information in the RAM is erased. The RAM is used to store information from the sensors, the results of calculations, and other data that are subject to constant change.

2. The type of memory that contains specific information about the vehicle and can be replaced or reprogrammed is called ___.

Answer The type of memory that contains specific information about the vehicle and can be replaced or reprogrammed or replaced is called PROM.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

3. Which is the simplest type of semiconductor.

Answer A diode is the simplest type of semiconductor.

4. What is meant by the term pulse width?

Answer Pulse width is the length of time, usually measured in milliseconds, during which something is kept on.

5. Explain how transistors can be used in automotive electronics.

Answer Transistors can be used as switches, amplifiers, and filters.

6. How should you test a diode with a multimeter?

Answer To test a diode using a multimeter you would first isolate the diode from the rest of the circuit. Set the meter to the diode check function if equipped or use the ohmmeter function. Connect the meter’s leads across the diode. Observe the reading on the meter. Then reverse the leads and observe the reading on the meter. The resistance in one direction should be very high or infinite, and in the other direction, the resistance should be very close to zero. A diode with high resistance in both directions is open, and one with low resistance in both directions is shorted.

7. What is the name of the module that allows the different serial buses in a multiplexed system to communicate with each other?

Answer A gateway module allows for data exchange between the different buses. It translates a message on one bus and transfers that message to another bus without changing the message.

8. What is the major difference between ROM and RAM memory in a microprocessor?

Answer Information in ROM cannot be erased; RAM information is erased whenever the ignition switch is turned off.

9. Describe the operation of the CAN data bus.

Answer Answers will vary but may include: The CAN bus uses twisted pair wiring, a gateway module, and termination resistors. The data is transferred using a voltage signal that pulses high and low.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

10. Compare and contrast Class B and Class C multiplexing.

Answer Answers will vary but may include: Class B is medium speed and is used for systems such as the instrument cluster. Class C is a high speed system and is used for powertrain control, braking, and similar systems that need real-time networking.

11. List three advantages of multiplexing.

Answer Three advantages are: reduces wiring, allows many computers and systems to network, and reduces redundancy.

12. Explain the function of a diode.

Answer A diode is a one-way valve for current flow. It can allow current to flow in one direction but blocks current flow in the opposite direction.

MULTIPLE CHOICE 1.

Which of the following is not made of semiconductor material? a. Zener diode b. Thermistor c. PM generator d. Hall-effect switch Answer: c. PM generators are not semiconductors. They are constructed of a permanent magnet and windings of wire.

2. Which of the following is a basic function of a computer? a. To store information b. To process information c. To send out commands d. All of the above Answer: d. All of the above

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that when positive voltage is present at the base of an NPN transistor, the transistor is turned on. Technician B says that when an NPN transistor is turned on, current flows through the collector and emitter of the transistor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

Answer: c. Both statements are correct. Applying voltage to the base turns on an NPN transistor, and current flows through the emitter and collector.

2. While checking an A/C compressor clutch coil clamping diode with a DMM, the meter shows infinite resistance when the diode is measured in both directions: Technician A says that the diode is open. Technician B says that all diodes should behave this way until a specified voltage is applied to them. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. When testing a diode with an ohmmeter, there should be low resistance in one direction and high resistance in the other. The zener diode is the type of diode that needs a specific voltage to allow current flow. A voltage suppressing, or clamping, diode is not a zener.

3. Technician A says that some types of voltage sensors provide input to the computer by modifying or controlling a constant, predetermined voltage signal. Technician B says that a coolant temperature sensor is a voltage-generating sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A coolant temperature sensor does not generate a voltage; rather it normally changes resistance as temperature changes.

4. Technician A says that multiplexing is a way to increase data communication without increasing the weight of the vehicle. Technician B says that multiplexing uses data buses to share information. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Multiplexing bus data use allows for more communication between modules using less wiring.

5. Technician A says that when a diode is placed in a circuit with the positive side of the circuit connected to the positive side of the diode and the negative side of the circuit connected to the negative side of the diode, the diode is said to have reverse bias. Technician B says that the diode’s P material is repelled by the positive charge of the circuit and is pushed toward the N material and that the N material is pushed toward the P. Who is correct? a. Technician A b. Both A and B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

c. Technician B d. Neither A nor B Answer: b. When a diode’s P material is connected to the positive charge in the circuit, it is forward biased, not reverse biased as stated by Technician A. Because like charges repel, the diode’s P conductive material is pushed toward the N material, and the N material is pushed toward the P, as stated by Technician B. 6. Technician A says that a capacitor always dis-charges with the same voltage it was charged with. Technician B says that current only flows through a capacitor when it is charging or discharging. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. A capacitor will discharge with the same voltage as the battery that charged it. Also, current can only flow during the period of time that a capacitor is either charging or discharging.

7. While discussing multiplex system protocols: Technician A says that CAN communications are based on variable pulse widths carried on a single bus wire. Technician B says that Class B communications offer real-time communications over a twisted pair of wires. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither is correct. Class B offers medium speed communication and relies on either a single wire or a two-wire differential bus. Class C is used for real-time control of the powertrain, vehicle dynamics, and brake-by-wire. This protocol can use a twisted pair, but shielded coaxial cable or fiber optics may be used for less noise interference. The predominant class C protocol is CAN. 8. Technician A says that the signal from a Hall-effect switch needs to pass through a Schmitt trigger before the computer can process it.

Technician B says that a Hall-effect switch produces an analog signal.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The signal from a Hall-effect switch is a weak analog signal. It is then sent to a Schmitt trigger, where it is digitized and conditioned into a clean square wave.

9. While diagnosing a network communication failure: Technician A checks for communication codes in the problem network. Technician B checks for DTCs in all networks and modules. Who is correct? a. Technician A b. Technician B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

c. Both A and B d. Neither A nor B Answer: c. Both are correct. Network failures will set communication codes in various systems and modules depending on the type of problem.

10. Technician A says that only the gateway module contains the terminating resistors in a HS-CAN system. Technician B says that MOST networks do not require terminating resistors. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Terminating resistors can be in any of the modules, not just the gateway.

MOST networks are not a type of CAN and do not require terminating resistors so Technician B is correct.

TECH MANUAL CONCEPT ACTIVITY 22-1 Onboard Network Data Bus Identification Below is an example of a computer data network (Figure 22-1).

FIGURE 22–1 A multiplexed system uses a serial data bus to allow communications between the various control modules.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 22: Basics of Electronics and Computer Systems

1.

Using a vehicle and a scan tool assigned to you by your instructor, determine and list what control modules are installed on the vehicle.

Answer Answers will vary but include: engine control, body control, ABS

2. Using the service information, determine the type of computer communication network(s) used by this vehicle.

Answer Answers will vary but include: CAN, LIN, MOST, FlexRay 3. List the modules and/or functions that utilize the high-speed data bus.

Answer Answers will vary but include: engine, ABS, transmission 4. List the modules and/or functions that utilize the medium-speed data bus.

Answer Answers will vary but include: body and infotainment 5. List the modules and/or functions that utilize the low-speed data bus.

Answer Answers will vary but include: windows and door locks, lighting

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 23: ELECTRICAL ACCESSORIES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 23-1 ......................................................................................................... 7

SHORT ANSWER 1.

Explain the principles of adaptive cruise control.

Answer The primary purpose of adaptive cruise control is to not only maintain a desired speed, but also to maintain a desired safe distance from the vehicle in front of you in your lane. Adaptive cruise control uses either radar or lasers to determine the distances to the vehicle in front of the vehicle being driven. If the distance decreases, the adaptive cruise can slow down and even apply the brakes to prevent a collision. If the distance increases, the system can speed the vehicle up until the desired distance is reached.

2. Describe telematics.

Answer Telematics is a technology that allows the transfer of data over a distance and from remote sources. It is best defined as the integrated use of telecommunications and information technology (IT).

3. What could be the problem when the vehicle’s dome light dims significantly when a power seat is moved?

Answer If the dome light dims, the seat may be binding or have some physical resistance on it.

Check under the seat for binding or obstructions.

4. What should be checked if none of the grids in a rear-window defogger work?

Answer When none of the grids in a rear window defogger operate, check the power and ground circuits to and from the grid.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

5. What component in a wiper system makes it possible for the wipers to shut off and rest in a certain location? How does it work?

Answer A park switch is incorporated into the motor. It operates off a cam or latch arm on the motor’s gear. The switch supplies voltage to the motor after the wipers have been turned off with their switch. This allows the motor to continue running until it reaches the park position.

6. Name the two most common problems that occur with power seats.

Answer The two most common problems with power seats are a tripped or constantly tripping circuit breaker and the inability of the seat to move in the desired direction due to binding or obstructions.

7. Explain the operation of the rear-window defroster grid.

Answer Answers will vary but may include: The defroster grid is a series of resistive lines wired in parallel along the rear glass. When turned on, voltage is dropped across the grid as current flows through each line. The current flow warms the grid and the glass.

8. Describe how express power windows function.

Answer Answers will vary but may include: Express windows allow for one-touch up or down window operation based on driver input to the window switch. Most system use current sensing electronics to determine when the window is fully up or down to shut off the motor.

9. Explain the operation of rain-sensing wiper systems.

Answer Answers will vary but may include: Rain-sensing wipers use a sensor that monitors the refraction of the light through the windshield glass. As rain falls and coats the glass, the light is refracted. When the refraction reaches a preset point, the wipers are turned on.

10. Describe basic horn circuit testing procedures.

Answer Answers will vary but may include: Verify if the horn operates, if not, press the horn pad and listen for the relay to click. The horn circuit can be tested at the relay by checking for ground by the horn switch, power to the relay, and by powering the horns at the relay to test horn operation.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

11. Explain adaptive and active seating.

Answer Answers will vary but may include: Adaptive seating moves the seats slightly while driving to help prevent fatigue. Active seating stimulates the spine and surrounding muscles to prevent the driver from getting sore.

MULTIPLE CHOICE 1.

Technician A says vehicles with electronic throttle control do not need a separate cruise control module, stepper motor, or cable to control engine speed. Technician B says a faulty brake light switch may cause the cruise control to not operate. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. On vehicles with electronic throttle control (drive-by-wire) the circuitry in the PCM operates the cruise control without the need for modules, cables, or stepper motors. Any faulty switch within the system can cause it not to operate normally.

2. Rear defrosters generally have a relay with a timer. This allows ___. a. the defogger to shut down after a predetermined length of time b. the defogger to function just until the rear window is clear c. the defogger to be independent of the ignition switch d. none of the above Answer: a. Typically, after about 10 minutes, a time delay circuit opens the ground path to the relay’s coil and the coil de-energizes. This shuts off power to the grids. The time delay circuit prevents the system from remaining on during periods of extended driving.

3. Which of the following can be sources of radio interference? a. Ignition system wiring b. Electrical power lines c. Neon signs d. All of the above Answer: d. All of the above.

4. The front passenger power window motor goes down but not back up. Technician A says a faulty power window relay is the cause. Technician B says the passenger window switch may be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. If the power window relay was bad, the motor would not move in either direction.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

5. Which of the following parts or circuits could cause one power window to not operate from either the master or the door switch? a. Power window fuse b. Power window motor c. Faulty wiring d. All of the above Answer: d. All could cause the problem, depending on the wiring in the system.

6. When diagnosing a vacuum/mechanical cruise control system that cannot maintain a constant speed, all of the following should be checked, except the ___. a. brake switch b. vacuum lines c. vacuum servo d. vehicle speed sensor Answer: a. If the system does not keep a constant speed, check the vacuum hose between the check valve and the servo, the check valve, the vacuum dump valve, servo, and speed sensor.

7. Which of the following is not a true statement? a. When all power windows do not operate, check the fuse and the wiring to the master switch, including the ground. b. When one power window does not operate, check the wiring to the individual switch, the switch, and the motor. Also check the window for binding in its tracks. c. When both rear power windows cannot be operated by their individual switches, check the lockout and master switch. d. When one power window moves in one direction only, check the fuse and the wiring to the master switch, including the ground.

Answer: d. When one power window moves in one direction only, check the wiring between the master switch and the individual switch. If the fuse were bad, none of the windows would work.

ASE-STYLE REVIEW QUESTIONS 1.

While discussing power door locks: Technician A says that if none of the locks work, the actuators at each door should be checked first. Technician B says that a scan tool is required to test the operation of the keyless entry remote. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. If none of the locks work, check the circuit protection devices and the wiring. Keyless remotes can often be checked using a TPMS tool in addition to a scan tool.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

2. A vehicle’s horns do not work. When the horn button is pressed, the relay can be heard clicking. Technician A says that the horn button is likely not completing the relay circuit to ground. Technician B says that the horn fuse may be blown. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct because the relay would not click if the horn button circuit were open or the fuse were blown..

3. The right front power door lock does not work: Technician A says that the motor might have a bad ground. Technician B says that the master door switch could be the problem. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct.

4. The reasons for slower than normal wiper operation are being discussed: Technician A says that the problem may be in the mechanical linkage. Technician B says that there may be excessive resistance in the electrical circuit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Either binding mechanical linkage or excessive electrical resistance can cause slower-than-normal wiper operation.

5. A six-way power seat does not work in any switch position: Technician A says to check the circuit breaker. Technician B says to use a continuity chart to test the switch. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. When power seats do not operate in any switch position, check for a tripped circuit breaker, check the power and ground circuits, and, finally, check for continuity in each switch position. Refer to the service manual for the expected continuity between the various terminals of the switch.

6. Technician A says that some antitheft systems sound an alarm if someone enters the vehicle without a key. Technician B says that some antitheft devices prevent the engine from starting. Who is correct? a. Technician A b. Technician B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Antitheft systems may have features that sound an alarm, disable the ignition, or deny entry to the vehicle.

7. The circuit breaker at a power seat motor continuously trips: Technician A says that this could be caused by a seat track problem that is causing mechanical resistance.

Technician B says that this could be caused by corrosion at the motor, which is causing electrical resistance. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A continuously tripping circuit breaker may be caused by binding or mechanical resistance. Check the seat tracks and under the seat for obstructions. High electrical resistance causes a decrease, not an increase in current flow, and would be unlikely to cause the circuit breaker to trip.

8. Technician A says that a resistance key has a small thermistor bonded to it. Technician B says that a transponder key sends a radio signal to the PCM. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Keys equipped with a transponder return a radio signal to the PCM. A resistance key has a small resistor, not a thermistor, bonded to it.

9. Technician A says that navigational systems rely on global positioning satellites.

Technician B says that navigational systems rely on information programmed in its memory and information stored on a CD or DVD. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Navigational systems rely on global positioning satellites, and a computer inside the vehicle compares the data it receives from the satellite with information stored in memory, or that it reads from a compact disc or DVD. 10. While diagnosing an adaptive cruise control system that does not hold the set speed: Technician A checks for dirt or obstructions around the radar unit. Technician B says the radar sensor may need to be realigned. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 23: Electrical Accessories

Answer: c. Adaptive cruise control systems may not activate if the forward-looking sensor is obstructed with dirt. A misaligned sensor can also cause the system to not operate.

TECH MANUAL CONCEPT ACTIVITY 23-1 Identify Electrical Accessories Make a list of 5 safety-related systems and 10 convenience accessory systems found on newer vehicles.

Answer Answers will vary but may include: ABS, traction control, stability control, lane keep assist, blind spot monitoring, adaptive headlamps, cross traffic alert systems, back up cameras, 360 degree cameras.

Remote keyless entry, push-to-start, automatic door locks, express (auto) power windows, power seats, power sliding doors, power liftgates, heated and cooled seats, adaptive cruise control, auto dimming mirrors, power folding mirrors, remote start, electronic keys.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 24: ENGINE PERFORMANCE SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 24-1 ......................................................................................................... 7 CONCEPT ACTIVITY 24-2 ......................................................................................................... 9 CONCEPT ACTIVITY 24-3 ......................................................................................................... 9 CONCEPT ACTIVITY 24-4........................................................................................................ 10

SHORT ANSWER 1.

Describe the difference between an open- and a closed-loop operation.

Answer When the engine is in open loop, there is no feedback from the oxygen sensors and so fuel calculation must be based on predetermined parameters contained in look-up tables. When the engine goes into closed loop, the PCM begins adjusting fuel and timing requirements by reacting to sensor feedback, mainly from the oxygen sensors.

2. Explain the use and importance of system strategy and look-up tables in the computerized control system.

Answer The computer depends on system strategies to actually learn from past experience.

This allows the system to adjust for wear and for differences in operating conditions.

Look-up tables are used to calculate fuel and timing needs when the system is in open loop.

3. Describe an OBD II warm-up cycle.

Answer OBD-II standards define a warm-up cycle as a period of vehicle operation in which the coolant rises by at least 40°F (4°C) and reaches at least 160°F (71°C).

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

4. Explain the trip and drive cycle in an OBD II system.

Answer The OBD-II trip consists of an engine start following an engine off period, with enough vehicle travel to allow the following monitoring sequences to complete their tests: (1) misfire, fuel system, and comprehensive system components; (2) EGR; and (3) H2OS. An OBD-II drive cycle consists of an engine start and sufficient vehicle operation to bring the vehicle into closed loop and to include whatever specific operating conditions are necessary to either initiate and complete a specific monitoring sequence or verify a symptom or a repair. To complete a drive cycle, all five monitors must be completed followed by the catalyst monitor.

5. Describe how engine misfire is detected in an OBD II system.

Answer An engine misfire is detected in an OBD-II system by the misfire monitor. It measures the contribution of each cylinder to engine power. This is accomplished using highly accurate crankshaft angle measurements of the rate of crankshaft acceleration after each cylinder fires. When a cylinder does not contribute to engine power, the expected rate of crankshaft acceleration does not occur.

6. Describe the purpose of having both upstream and downstream oxygen sensors in an exhaust system.

Answer The downstream oxygen sensor is used primarily to monitor the operation of the catalytic converter and the upstream sensor is primarily used for fuel control.

7. Briefly describe the monitors in an OBD II system.

Answer Monitors in an OBD-II system include: • Catalyst efficiency monitor: gives an indication of the efficiency of the catalytic converter.

• Engine misfire monitor: measures the amount each cylinder contributes to engine power. A cylinder not contributing to engine power is flagged as a misfire. There are two types of misfires. Type A misfires, which are detected over a 200 rpm period and are considered excessive if between 2 percent and 20 percent. Type B misfires, which are checked over a 1,000 rpm range and are flagged if they exceed 2 percent to 3 percent.

• Fuel system monitor: checks short-term (STFT) and long-term (LTFT) fuel trim while the PCM is operating in closed loop.

• Heated oxygen sensor: measures the response time and the frequency of the oxygen sensor signals and whether the heater is functioning. It can detect a lazy or faulty sensor.

• EGR system monitor: checks the efficiency of the EGR system. A variety of strategies may be employed by various manufacturers to check their systems,

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

• •

•

•

•

ranging from measuring the pressure differential on each side of the EGR valve to opening the valve and watching for a change in the MAP signal.

EVAP system monitor: tests the ability of the fuel tank to hold pressure and the purge system to vent gas fumes to the charcoal canister.

AIR system monitor: checks the operation of the AIR system by turning the system to inject air upstream of the oxygen sensor and monitoring its signal for an expected increase in oxygen content.

Thermostat monitor: checks the engine and its cooling system for defects that would affect engine temperature and prevent the engine from reaching normal operating temperature. The monitor checks the time it takes for the cylinder head to reach a specific temperature.

PCV monitor: looks at HO2S signals for consistent lean readings and the lack of switching from rich to lean. Abnormal signals can be the result of a leaking PCV system.

Comprehensive component monitor: checks any electronic input that could affect emissions. It employs two strategies for input sensors. One looks for out-of range values from sensors as they are received at the analog/digital (A/D) converter, and the other performs a rationality check of sensor values. It also checks the operation of each of the outputs that affect emissions. The output state monitor of the comprehensive component monitor (CCM) checks most of the outputs by monitoring the voltage of each solenoid, relay, or actuator at the output driver of the PCM.

8. Describe how freeze-frame data can be important in performing diagnostics.

Answer Answers will vary but may include: A freeze frame is stored when a code is set. The FF includes some data parameters of engine operation when the code set to help the technician determine the cause of the fault and to operate the vehicle in a similar manner to verify if the concern has been corrected.

9. Explain three functions of the ignition system.

Answer Answers will vary but may include: To supply spark to the spark plugs to ignite the air/fuel mixture to the right cylinder at the right time while adapting to for engine speed and load.

MULTIPLE CHOICE 1.

Which sensor is used for misfire monitoring on OBD II systems? a. Oxygen sensor b. Camshaft position sensor c. Crankshaft position sensor d. DPFE sensor

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

Answer: c. A crankshaft position sensor is the primary sensor used by OBD to detect a cylinder misfire.

2. Which of the following statements is not true? a. DTCs that will not affect emissions will never illuminate the MIL b. An active or current DTC represents a fault that was detected and occurred during two trips c. When a two-trip fault is detected for the second time, a DTC is stored as a pending code. d. There are some DTCs that will set in one trip.

Answer: c. When a two trip fault is detected for the first time, a DTC is stored as a pending code. A pending DTC is a code representing a fault that has occurred, but that has not occurred enough times to illuminate the MIL. 3. A computer is capable of doing all of the following except ___. a. receive input data b. process input data according to a program and monitor output action c. control the vehicle’s operating conditions d. store data and information Answer: c. The computer has no control over a vehicle’s operating conditions.

4. Which of the following memory circuits is used to store trouble codes and other temporary information? a. Read-only memory b. Programmed read-only memory c. Random access memory d. All of the above Answer: c. The random access memory (RAM) stores trouble codes and other temporary information in much the same way that a scratch pad is used.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that the oxygen sensor provides the major input during the openloop mode. Technician B says that the coolant temperature sensor input is not used during open-loop mode operation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Open-loop operation relies on system strategies, lookup tables, and sensor input. The oxygen sensor is not the major input during open loop. The ECT is the primary sensor used to switch from open to closed loop.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

2. While discussing OBD II systems: Technician A says that the PCM illuminates the MIL if a defect causes emission levels to exceed 2.5 times the emission standards for that model year vehicle. Technician B says that if a misfire condition threatens engine or catalyst damage, the PCM flashes the MIL. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A flashing MIL alerts the driver to imminent engine or catalyst damage. The MIL is illuminated when emissions exceed 1.5 times, not 2.5 times.

3. While discussing the catalyst efficiency monitor: Technician A says that if the catalytic converter is not reducing emissions properly, the voltage frequency increases on the downstream HO2S. Technician B says that if a fault occurs in the catalyst monitor system on three drive cycles, the MIL will be illuminated. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. An ineffective catalytic converter would be indicated by an increase in the voltage frequency of the downstream oxygen sensor.

When a fault is detected by the catalyst monitor on three drive cycles, the MIL is illuminated.

4. While discussing monitoring systems: Technician A says that the fuel system monitor checks the short-term and long-term fuel trims. Technician B says that the heated oxygen sensor monitoring system checks lean-to-rich and rich-to-lean response times.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The function of the fuel system monitor is to make sure short and long term fuel trims remain within normal parameters. The oxygen sensor monitor detects the time it take the sensor to switch and how often it switches rich and lean.

5. While discussing the comprehensive monitoring system: Technician A says that it tests various input circuits. Technician B says that it tests various output circuits. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The comprehensive monitor is used to detect physical wiring problems on input and output circuit.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

6. While discussing the MIL on OBD II systems: Technician A says that the MIL will flash if the PCM detects a fault that would damage the catalytic converter. Technician B says that whenever the PCM has detected a fault, it will turn on the MIL. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. A flashing MIL can mean a fault is detected that could result in a damaged catalytic converter. Not all faults will cause the PCM to illuminate the MIL. 7. While discussing diagnostic procedures: Technician A says that after the visual inspection has been performed, the DTCs should be cleared from the memory of the PCM. Technician B says that serial data can be helpful when there are no DTCs but there is a fault in the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. Serial data can be essential to solving no-faultcode drivability problems. Codes should not be erased after a visual inspection, as stated by Technician A. 8. Technician A says that the enable criteria are the criteria that must be met before the PCM completes a monitor test. Technician B says that a drive cycle includes operating the vehicle under specific conditions so that a monitor test can be completed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Enable criteria must be met before the PCM completes a monitor test. A drive cycle includes operating the vehicle under specific operating conditions until all, or most, of the monitors have completed their functions.

9. While discussing PCM monitor tests: Technician A says that some monitors only run after another monitor completes. Technician B says that the monitor tests are run when the scan tool activates them. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. Monitors are run during normal driving when enable criteria are met.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

10. While discussing the misfire monitor: Technician A says that while detecting type A misfires, the monitor checks cylinder misfiring over a 500-revolution period. Technician B says that while detecting type B misfires, the monitor checks cylinder misfires over a 1,000-revolution period. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Type A misfires are checked over a 200-rpm, not a 500-rpm, range.

TECH MANUAL CONCEPT ACTIVITY 24-1 Ignition Systems Comparison Compare the two ignition systems shown in Figures 24-1 and 24-2.

FIGURE 24–1 One type of electronic distributor type ignition system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

FIGURE 24–2 This wiring schematic shows the grounding control of the ignition coil module used in the waste spark ignition system.

1.

List the locations for mechanical wear in the distributor ignition (DI) system.

Answer Distributor gear, distributor bushing(s)

2. List the components of the DI system that need periodic service or replacement.

Answer Distributor cap, rotor, plugs, plug wires 3. List the locations for wear in the distributorless electronic ignition (EI) system.

Answer Plugs, plug wires 4. List the components of the EI system that need periodic service or replacement.

Answer Plugs, plug wires 5. Explain the benefits of EI systems compared to DI systems.

Answer Answers will vary but may include reduced wear, more precise spark timing, and better coil saturation.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

CONCEPT ACTIVITY 24-2 Identify the Operating Circuits of a Carburetor Referring to Figure 24-3, fill in the blanks with the names of the operating circuits of a carburetor.

FIGURE 24–3 Basic parts of a carburetor.

1.

2.

3.

4.

5.

__________ __________ __________ __________ __________ Answer Answer order not important 1. float circuit 2. main metering circuit 3. idle circuit 4. Enrichment or power circuit 5. Choke circuit

CONCEPT ACTIVITY 24-3 Comparison of TBI and PFI 1.

Compare an older TBI or carburetor air cleaner assembly and a newer port fuel injected (PFI) air cleaner assembly. Note the location of the air inlet, the materials, hoses, heat riser, and filter elements.

Answer Generally found on top of the engine.

2. What is the purpose of the heat riser tube from the exhaust manifold to the air cleaner housing?

Answer Purposes include to warm the air entering the engine, warm the intake to prevent cold fuel from puddling in the intake, and prevent freezing of the throttle body.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 24: Engine Performance Systems

3. Why are heat risers not used on fuel injection systems?

Answer Fuel does not pass through the intake.

CONCEPT ACTIVITY 24-4 OBD Systems 1.

Compare and contrast five major differences between OBD I and OBD II. Answer Answers will vary but may include catalyst monitoring, evaporative monitoring, misfire monitoring, EGR, PCV, thermostat monitoring, MIL triggered by emission levels, DLC, or DTCs.

2. Describe the location of the DLC on OBD II vehicles.

Answer Left side of dash area 3. Explain what is required for the OBD II system to illuminate the MIL. Answer Emissions to exceed 1.5 the federal test parameter 4. Describe multiplexing.

Answer Allowing computers (modules) to communicate using dedicated transmission lines and communication protocols

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 25: DETAILED DIAGNOSIS AND SENSORS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 25-1 ......................................................................................................... 6 CONCEPT ACTIVITY 25-2 ......................................................................................................... 7 CONCEPT ACTIVITY 25-3 ......................................................................................................... 8

SHORT ANSWER 1.

OBD II systems use several modes of operation. List three of them.

Answer OBD II modes include mode 1—display current data; mode 2—display freeze frame data; mode 3—display trouble codes; mode 4—clear emissions related data; modes 5, 6, 7—display test parameters and results; mode 8—request control of onboard systems; mode 9—in use performance tracking; and mode 10—display permanent trouble codes.

2. List the four ways that individual components can be checked.

Answer Individual components may be checked by (1) visual inspections, (2) ohmmeter checks, (3) voltmeter checks, and, (4) lab scope checks.

3. Explain how a bad circuit ground can affect a sensor’s reference voltage.

Answer A bad circuit ground affects a sensor’s reference voltage by increasing reference voltage. In series circuits when additional resistance is added to a circuit from something like a corroded ground connection, a reduction of voltage at the load is expected. Because reference voltage circuits are series parallel circuits, the opposite is true. An increase in resistance at the ground increases reference voltage sent to the sensors. This causes them to provide faulty information to the PCM. Poor grounds can

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

also allow EMI, or noise, to be present on the voltage reference signal. This also affects the accuracy of sensor input.

4. List six steps involved in performing a visual inspection.

Answer Steps involved in performing a visual inspection: • Check all vacuum hoses. Make sure they are connected and are not pinched, cut, or cracked.

• Check the condition and tension of the generator drive belt.

• Check the battery and battery connections. Look for loose and corroded connections and damaged or burned wires under the hood.

• Inspect the wiring for sensors and outputs.

• Check the level and condition of the engine’s coolant.

• Check the air filter. Also check the air intake system for restrictions and leaks.

Check for exhaust system leaks.

5. Many control systems have operating modes that can be accessed with a scan tool to control the operation of an output. What are the names of the two most common modes for controlling outputs?

Answer The output state control (OSC) and output test mode (OTM).

6. Explain how a TP sensor provides input to the PCM. Answer Answers will vary but may include: A throttle position sensors is a three wire potentiometer, which varies the voltage signal back to the computer. The signal return is connected to a moveable contact or wiper inside the sensor. As the throttle moves, the wiper contacts the resistor inside the sensor. The varying resistance changes the voltage signal returning to the computer.

7. Explain how a MAP sensor operates.

Answer Answers will vary but may include: A MAP sensor measures manifold pressure against an absolute vacuum. The sensor changes the voltage supplied by the computer and sends the signal back to the computer.

8. Explain how an O2 sensor operates.

Answer Answers will vary but may include: The oxygen sensor produces a voltage based on the amount of oxygen present in the exhaust compared to the outside air.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

9. What is the purpose of the intake air temperature sensor?

Answer Answers will vary but may include: The intake air temperature sensor is used to determine the air mass entering the engine and is used to calculate fuel and spark.

10. Explain how a hot wire mass airflow sensor works.

Answer Answers will vary but may include: In a hot-wire-type MAF, a wire, called the hot wire, is positioned so the intake air flows over it. The sensor also has a thermistor located beside the hot wire that measures intake air temperature. Current from the PCM keeps the hot wire at a constant temperature above ambient temperature, normally 392°F (200°C). Airflow past the hot wire causes it to lose heat and the PCM responds by sending more current to the wire. The increased current flow keeps the hot wire at its desired temperature. The current required to maintain the hot wire’s temperature is proportional to mass airflow. The sensor measures the current and sends a voltage signal to the PCM. The PCM interprets the signal to determine mass airflow.

MULTIPLE CHOICE 1.

Which of the following statements about zirconium oxygen sensors is not true? a. The normal operating range for an O2S is between 0 and 1 volt. b. If the sensor’s voltage toggles between 0 volts and 500 millivolts, it is operating normally. c. The voltage signal from an upstream O2S should have seven cross counts within 5 seconds with the engine running without a load at 2,500 rpm. d. Engine control systems monitor the activity of the O2S and store a code when the sensor’s output is not within the desired range.

Answer: b. If the sensor’s voltage toggles between zero volts and 500 millivolts, it is toggling within its normal range but it is not operating normally. It biased low or lean.

2. The catalyst monitor test may fail for all of these reasons, except ___. a. defective upstream or downstream oxygen sensor circuits b. a leaking exhaust c. fuel contaminants d. ignition system misfire Answer: d. ignition faults should not affect the catalyst monitor test results, they would affect the fuel system monitor.

3. A defective IAT sensor or circuit may cause the following problems, except ___. a. hard engine starting b. rich or lean air-fuel ratio c. improper converter clutch lockup d. reduced fuel economy Answer: c. A bad ECT would affect torque converter operation, not an IAT.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

4. Which of the following is the least likely cause of a no-start condition? a. Faulty CKP sensor b. Faulty KS c. Fuel or ignition system faults d. Faulty PCM wiring Answer: b. A bad KS is most likely to cause engine detonation or reduced spark advance and poor fuel economy.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that an oxygen sensor can be a voltage-producing sensor. Technician B says that an oxygen sensor is a thermistor sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. The oxygen sensor produces voltage. It is not a thermistor as stated by Technician B.

2. While discussing zirconium O2S diagnosis: Technician A says that the voltage signal on a satisfactory O2S should always be cycling between 0.5 volt and 1 volt. Technician B says that a contaminated O2S may produce a continually high-voltage signal. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. A good O2 sensor should toggle between 0.2 V and 0.8 V. A contaminated O2 sensor would be biased rich and produce a continually high voltage signal.

3. While discussing ECT sensor diagnosis: Technician A says that a defective ECT sensor may cause hard cold engine starting. Technician B says that a defective ECT sensor may cause improper operation of emission control devices. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A faulty coolant temperature sensor can affect engine and emission control system operation.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

4. While discussing Hall-effect vehicle speed sensor tests: Technician A says to use an ohmmeter to test the resistance of the coil. Technician B says that the voltage generated by the sensor can be measured by connecting a voltmeter across the sensor’s terminals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Only b is correct, there is no coil in a Hall-effect switch.

5. While discussing TP sensor diagnosis: Technician A says that a four-wire TP sensor contains an idle switch. Technician B says that in some applications, the TP sensor mounting bolts may be loosened and the TP sensor housing rotated to adjust the voltage signal with the throttle in the idle position. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Some TP sensors contain an idle switch, used to determine when the throttle is closed and some sensors can be adjusted.

6. While diagnosing the cause of a hard starting condition: Technician A checks the ECT sensor. Technician B checks the MAP sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Both engine coolant and manifold pressure sensors are used for proper engine starting and running.

7. While discussing testing OBD II system components: Technician A says that a test light can be used to test O2S output. Technician B says that a digital voltmeter can be used to test the O2S. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. A high-impedance digital voltmeter should be used to test OBD-II circuits.

8. When testing a frequency varying MAF: Technician A says that the frequency should increase with an increase in engine speed. Technician B says that when observed on a lab scope, the signal from the sensor should be a square wave. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

Answer: c. Both technicians are correct. Increased engine speed should increase the frequency of the output signal, which should also be a digital square wave pattern.

9. Technician A says that a faulty MAF sensor can cause the engine to run lean.

Technician B says that a faulty MAP sensor can cause the engine to not start. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. A faulty MAF will cause the engine to run lean.

However, Technician B is wrong because the MAP’s inputs are only looked at once the engine is started.

10. While discussing the MIL on OBD II systems: Technician A says that the MIL will flash if the PCM detects a fault in a sensor or circuit. Technician B says that as soon as the PCM has detected a fault, it will turn on the MIL. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The MIL illuminates only when the system sets a code that is emissionrelated.

TECH MANUAL CONCEPT ACTIVITY 25-1 Measure Engine Coolant Temperature (ECT) Resistance 1.

Obtain from your instructor several coolant and air temperature sensors. Use a digital multimeter (DMM) to test their resistance at room temperature.

Sensor 1 resistance __________ Approximate temperature __________ Sensor 2 resistance __________ Approximate temperature __________ Sensor 3 resistance __________ Approximate temperature __________ Sensor 4 resistance __________ Approximate temperature __________ Answer Answers will vary but include: 40–100k ohms, room temperature

2. Obtain from your instructor several coolant and air temperature sensors. Use a digital multimeter (DMM) to test their resistance at room temperature.

Sensor 1 resistance __________ Approximate temperature __________ Sensor 2 resistance __________ Approximate temperature __________

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

Sensor 3 resistance __________ Approximate temperature __________ Sensor 4 resistance __________ Approximate temperature __________ Answer Answers will vary but include: 40–100k ohms, less than room temperature 3. How much did the resistance change compared to the temperature change?

Answer Answers will vary but include: slightly to a lot 4. Obtain from your instructor several coolant and air temperature sensors. Use a digital multimeter (DMM) to test their resistance at room temperature.

Sensor 1 resistance __________ Approximate temperature __________ Sensor 2 resistance __________ Approximate temperature __________ Sensor 3 resistance __________ Approximate temperature __________ Sensor 4 resistance __________ Approximate temperature __________ Answer Answers will vary but include: 40–100k ohms, over room temperature 5. How much did the resistance change compared to the temperature change?

Answer Answers will vary but include: slightly to a lot 6. Which sensors are PTC and which are NTC sensors?

Answer Answers will vary based on sensors used.

CONCEPT ACTIVITY 25-2 Identify the Operating Circuits of a Carburetor 1.

Obtain several throttle position (TP) sensors and fuel level sensors. Use a DMM to measure the resistance from the voltage to ground terminals.

Sensor 1 resistance __________ Sensor 2 resistance __________ Sensor 3 resistance __________ Answer Answers will vary but include: 40–200 ohms

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

2. Next, measure the resistance from the voltage to signal return terminals.

Sensor 1 resistance __________ Sensor 2 resistance __________ Sensor 3 resistance __________ Answer Answers will vary but include: 40–200 ohms 3. Now move the sensor position and remeasure the resistance.

Sensor 1 resistance __________ Sensor 2 resistance __________ Sensor 3 resistance __________ Answer Answers will vary but include: 40–200 ohms 4. How do the resistances of the different sensors compare to each other?

Answer Answers will vary based on sensors used.

5. Why might one type of sensor have a different resistance than another sensor?

Answer Answers will vary but include: based on manufacturer, type of sensor 6. Describe other circuits or systems that may use variable resistors.

Answer Answers will vary but include: dash lighting dimmer switch, volume control

CONCEPT ACTIVITY 25-3 Computer Output Controls Obtain a scan tool and lab vehicle from your instructor. Connect the scan tool to the data link connector (DLC) and begin communication. Locate the output control commands.

1.

List the available systems or components that can be controlled by the scan tool.

Answer Answers will vary but include: engine control, body control, ABS, TPMS, and lighting systems

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 25: Detailed Diagnosis and Sensors

2. With guidance from your instructor, attempt to command various systems or components on or off with the scan tool. Note your results.

Answer Answers will vary but include: turn lights on/off, activate horn, windows, door locks, wipers, and instrument panel tests

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 26: IGNITION SYSTEMS

TABLE OF CONTENTS Short Answer ...................................................................................................................... 2 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 26-1 ......................................................................................................... 7 CONCEPT ACTIVITY 26-2 ......................................................................................................... 9 CONCEPT ACTIVITY 26-3 ........................................................................................................ 10 CONCEPT ACTIVITY 26-4........................................................................................................ 10 CONCEPT ACTIVITY 26-5 ........................................................................................................ 12 CONCEPT ACTIVITY 26-6........................................................................................................ 14 CONCEPT ACTIVITY 26-7 ........................................................................................................ 15 CONCEPT ACTIVITY 26-8........................................................................................................ 16 CONCEPT ACTIVITY 26-9........................................................................................................ 17 CONCEPT ACTIVITY 26-10 ...................................................................................................... 18 CONCEPT ACTIVITY 26-11 ....................................................................................................... 19 CONCEPT ACTIVITY 26-12 ..................................................................................................... 20 CONCEPT ACTIVITY 26-13 ..................................................................................................... 20 CONCEPT ACTIVITY 26-4........................................................................................................ 10 CONCEPT ACTIVITY 26-5 ........................................................................................................ 12 CONCEPT ACTIVITY 26-6........................................................................................................ 13 CONCEPT ACTIVITY 26-7 ........................................................................................................ 14 CONCEPT ACTIVITY 26-8........................................................................................................ 15 CONCEPT ACTIVITY 26-9........................................................................................................ 16 CONCEPT ACTIVITY 26-10 ...................................................................................................... 17 CONCEPT ACTIVITY 26-11 ....................................................................................................... 18 CONCEPT ACTIVITY 26-12 ...................................................................................................... 19 CONCEPT ACTIVITY 26-13 ...................................................................................................... 19

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

SHORT ANSWER 1.

Explain how voltage is induced in a permanent magnet pickup coil as the reluctor approaches alignment with the pickup coil.

Answer The magnetic pulse or PM generator operates on the principles of electromagnetism. A voltage is induced in a conductor when a magnetic field passes over the conductor or when the conductor moves over a magnetic field. The magnetic field is provided by a magnet in the pickup unit, and the rotating trigger wheel provides the required movement through the magnetic field to induce voltage.

2. Explain why dwell time is important to ignition system operation.

Answer Dwell is the period of time in which current is flowing through the primary winding of the coil. The longer current is allowed to flow, the greater coil saturation will be. A fully saturated coil can better provide maximum secondary voltage.

3. Name the engine operating conditions that most affect ignition timing requirements.

Answer Engine timing requirements are mostly affected by engine speed and load, although EI systems also look at inputs from other sensors to determine the ideal timing.

4. Explain how the plugs fire in a two-plug-per-coil DIS system.

Answer Both ends of the coil’s secondary side are directly connected to a spark plug, which means that two plugs are ignited at the same time; one is fired on the compression stroke of one cylinder and the other is fired on the exhaust stroke of the companion cylinder. One plug fires from positive to negative and the other plugs fire negative to positive.

5. Why is high voltage needed to establish a spark across the gap of a spark plug?

Answer High voltage is needed to supply enough electrical pressure to allow the electrons to jump across the gap and establish a complete circuit. Once the circuit is complete, current flows and an arc forms across the gap.

6. List the advantages of having one ignition coil per cylinder.

Answer Having one coil for each spark plug allows for more time between each firing, which increases the life of the coil by allowing it to cool. In addition, it also allows for more

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

saturation time, which increases the coil’s voltage output at high engine speeds. The increased output makes the coils more effective with lean fuel mixtures, which require higher firing voltages. Another advantage of using the coil-per-cylinder system is the ignition timing at each cylinder can be individually changed for maximum performance and to respond to knock sensor signals. Other advantages of a coil-per-cylinder system are that all of the engine’s spark plugs fire in the same direction and coil failure will affect only one cylinder.

7. Explain the components and operation of a Hall-effect sensor.

Answer Many Hall-effect sensors rely on pulleys or harmonic balancers with interrupter rings or shutters. In many cases, the crankshaft pulley has half as many windows as the engine has cylinders. As the crankshaft rotates and the interrupter passes in and out of the Hall-effect switch, the switch turns the module reference voltage on and off.

The signals are identical and the control module cannot distinguish which of these signals to assign to a particular coil.

8. Explain the construction and operation of the ignition coil.

Answer Answers will vary but may include: An ignition coil contains two windings, a heavy primary wire and a lighter secondary wire, wrapped around an iron core. Current flow through the primary generates a magnetic field. When the current flow is turned off, the field collapses across the secondary winding, which produces the high-voltage spark.

9. Explain why timing advance is necessary.

Answer Answers will vary but may include: Ignition timing must advance or take place sooner as engine speed increases because there is less time between firing events and the generation and delivery of spark takes a fixed amount of time to accomplish.

10. Explain why spark plug wires have high resistance.

Answer Answers will vary but may include: Plug wires typically have high resistance to decrease radio frequency interference in the electrical system.

MULTIPLE CHOICE 1.

What happens when the low-voltage current flow in the coil primary winding is interrupted by the switching device? a. The magnetic field collapses. b. A high-voltage is induced in the coil secondary winding. c. Both A and B. d. Neither A nor B.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

Answer: c. When current flowing through the primary winding is interrupted, the magnetic field collapses and a high voltage surge occurs in the coil secondary winding.

2. Which of the following is a function of all ignition systems? a. To generate sufficient voltage to force a spark across the spark plug gap b. To time the arrival of the spark to coincide with the movement of the engine’s pistons c. To vary the spark arrival time based on varying operating conditions d. All of the above Answer: d. All of the above 3. Reach, heat range, and air gap are all characteristics that affect the performance of which ignition system component? a. Ignition coils b. Ignition cables c. Spark plugs d. Ignition modules Answer: c. Reach, heat range, and air gap are features of spark plugs.

4. The magnetic field surrounding the coil in a magnetic pulse generator moves when the ___. a. reluctor tooth approaches the coil b. reluctor tooth begins to move away from the pickup coil pole c. reluctor is aligned with the pickup coil pole d. both A and B Answer: d. Both statements A and B are correct. The magnetic field surrounding the coil moves both when a tooth is approaching and when moving away from the coil.

5. Which of the following electronic switching devices has a reluctor with wide shutters rather than teeth? a. Magnetic pulse generator b. Optical sensor c. Hall-effect sensor d. All of the above Answer: c. A Hall-effect sensor has shutters rather than teeth.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a magnetoresistive sensor is equipped with a permanent magnet. Technician B says that a Hall-effect switch is equipped with a permanent magnet. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

Answer: c. Both a hall-effect switch and a magnetic pulse generator have permanent magnets.

2. While discussing ignition systems: Technician A says that an ignition system must supply high-voltage surges to the spark plugs. Technician B says that the system must maintain the spark long enough to burn all of the air-fuel mixture in the cylinder. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The ignition system must both supply high voltage to the spark plugs and also maintain the spark long enough to burn all of the air/fuel mixture.

3. While discussing ignition timing requirements: Technician A says that more advanced timing is desired when the engine is under a heavy load. Technician B says that more advanced timing is desired when the engine is running at low engine speeds. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither Technician is correct. Advanced timing is desirable when the engine is operating at high engine speeds, not low as stated by Technician B. When the engine is operating under heavy load, timing should be slightly retarded, not advanced as stated by Technician A. 4. While discussing secondary voltage: Technician A says that the normal required secondary voltage is higher at idle speed than at wide-open throttle conditions.

Technician B says that the maximum available secondary voltage must always exceed the normally required secondary voltage. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. Maximum available secondary voltage should always exceed what is required. Maximum required secondary voltage is higher at wide open throttle, not at idle as stated by Technician A 5. Technician A says that an ignition system must generate sufficient voltage to force a spark across the spark plug gap. Technician B says that the ignition system must time the arrival of the spark to coincide with the movement of the engine’s pistons and vary it according to the operating conditions of the engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

Answer: c. Both technicians are correct. The ignition system must both supply sufficient voltage to jump across the air gap and also deliver it at the correct time.

6. In EI systems using one ignition coil for every two cylinders: Technician A says that two plugs fire at the same time with the same voltage used by each spark plug. Technician B says that one plug fires in the normal direction (center to side electrode) and the other in reversed polarity (side to center). Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Since one plug fires with a reverse voltage, the amount of voltage required to jump the gap at that plug will be different from the other plug.

7. While discussing EI systems: Technician A says that all systems rely on CKP and CMP signals to synchronize the ignition system with piston movement. Technician B says that CKP and CMP signals are used to synchronize the operation of the ignition and fuel injection systems with piston position. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. All systems have a CKP to monitor crankshaft position, engine speed, and/or the relative position of each cylinder. Not all systems have a CMP, some have more than one. The signals from a CMP sensor are used for cylinder identification and for verifying the correlation between the position of the crankshaft and the camshafts.

Inputs from these sensors are critical to the operation of the fuel injection and ignition systems.

8. While discussing EI systems: Technician A says that when the engine is being cranked, the PCM relies only on the signals from the ECT to determine initial ignition timing.

Technician B says that when an engine is initially started and is running at a predetermined speed, the PCM looks at several inputs, including engine speed, load, throttle position, and engine coolant temperature, and makes adjustments accordingly.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. When the engine is cranked for starting, the PCM sets the timing at a fixed value. This value is used until the engine is running at a predetermined speed. Once that speed is met, the PCM looks at several inputs, including engine speed, load, throttle position, and engine coolant temperature, and makes adjustments accordingly.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

9. Technician A says the switching device controls the flow of current through the coil primary winding. Technician B says that when the switching device stops supplying current to the coil primary winding, it is time to fire the spark plug. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Starting and stopping the current flow through the primary coil winding initiates the process of supplying spark.

10. While discussing spark plugs: Technician A says that too narrow of a spark plug gap can cause a rough idle and premature wear of the electrodes. Technician B says that a spark plug with the wrong reach can cause preignition. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct.

TECH MANUAL CONCEPT ACTIVITY 26-1 Identify DI Components 1.

Identify the components of the distributor ignition (DI) system in Figure 26-1.

FIGURE 26–1 The ignition system is two circuits. The primary circuit carries the low voltage, and the secondary circuit carries the high voltage. a. __________ Answer Ignition switch © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

b. __________ Answer Ignition coil c. __________ Answer Primary coil winding d. __________ Answer Secondary coil winding e. __________ Answer Distributor cam f.

__________ Answer Distributor housing

g.

__________ Answer Spark plug wires

h. __________ Answer Distributor cap i.

__________ Answer Ignition rotor

j.

__________ Answer Spark plugs

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

2. List the components of the primary ignition system from Figure 26-1.

Answer Battery, ignition switch, coil primary, primary switching device 3. List the components of the secondary ignition system from Figure 26-1.

Answer Distributor cap, rotor, plug wires, plugs, secondary coil windings 4. Which component is part of the primary and secondary ignition systems?

Answer Ignition coil

CONCEPT ACTIVITY 26-2 Ignition Coils 1.

If a coil has 200 primary windings and 20,000 secondary windings, what is the ratio between the primary and secondary?

Answer 100:1

2. Would you expect the resistance of the primary windings to be high or low?

Answer Low 3. Would you expect the resistance of the secondary windings to be high or low?

Answer High 4. What is the purpose of the iron core in the coil?

Answer To increase the strength of the magnetic field 5. An ignition coil is a step-up transformer, meaning it boosts voltage from low to high.

What are other common examples of transformers?

Answer Answers will vary but may include cell phone chargers, power adaptors, and/or utility pole transformers.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

CONCEPT ACTIVITY 26-3 Dwell Dwell is the amount of time, in degrees, that the coil has current flowing through the primary windings. This time is important for the coil to fully charge.

1.

What two factors determine the amount of dwell time for each cylinder?

Answer

rpm and the number of coils 2. Describe the effects of insufficient dwell time.

Answer

Weak spark, incomplete combustion CONCEPT ACTIVITY 26-4 Permanent Magnet Sensors Obtain a selection of permanent magnet type sensors and a DMM from your instructor.

1.

Which type of voltage do you think these sensors generate and why?

Answer Answers will vary but include: AC voltage, due to induced voltage type sensor

2. Measure the resistance of the sensor coils and record your readings. Resistances Answer Answers will vary but include: 400–2000 ohms 3. Why do the sensors have high resistance?

Answer Coil resistance to current flow 4. What reading would an open coil show?

Answer Open lead, OL, infinite or similar 5. What reading would a shorted coil show?

Answer Lower resistance than specified

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

6. Are any of the sensors you tested open or shorted?

Answer Answers will vary but include: yes or no 7. Do any of the sensors you tested show excessively high resistance?

Answer Answers will vary but include: yes or no 8. How would excessive resistance affect the performance of the sensor?

Answer Reduced signal output voltage Set the DMM to measure AC voltage. Connect the DMM leads to the sensor’s terminals. Rotate the sensor-timing disk or move a magnet back and forth very close to the sensor end of the pickup.

9. Does the sensor produce AC voltage?

Answer Answers will vary but include: yes or no 10. Why is AC voltage produced?

Answer Moving magnetic fields across a conductor produce AC voltage.

11. Describe the voltage output as you increase the rotation speed of the sensor.

Answer Answers will vary but include: voltage increases with speed increase Connect a digital storage oscilloscope or graphing multimeter (DSO/GMM) to the sensor’s terminals. Rotate the sensor-timing disk or move a magnet back and forth very close to the sensor end of the pickup. Obtain a waveform of the sensor output.

12. Draw the waveform pattern here.

Answer

Answers will vary but include:

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

13. Describe the sections of the waveform.

Answer Answers will vary but include: rising voltage, 0 voltage, falling voltage 14. What happens to the waveform as the sensor rotates faster?

Answer Answers will vary but include: signal increases in frequency 15. What type of signal does this sensor produce?

Answer Answers will vary but include: analog (AC) or digital (DC) 16. Of the three tests you have performed on these sensors—resistance, AC voltage, and waveform observation—which provides the best information for diagnostics and why?

Answer Answers will vary but include: voltage output or waveform observation due to ability to quantify sensor output

CONCEPT ACTIVITY 26-5 Hall-Effect Sensors 1.

Why do Hall-effect sensors have three wires?

Answer Power, ground, and signal return

Connect a DMM to the power and ground terminals of a Hall-effect sensor and check its resistance.

2. What resistance reading did you obtain from the Hall-effect sensor?

Answer Answers will vary but include: no reading

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

3. Why do you think you got this reading?

Answer Answers will vary but include: Hall-effects typically do not show meaningful resistance Connect a DMM to a Hall-effect sensor on a vehicle.

4. Sensor location and use: Answer Answers will vary but include: at crankshaft for engine speed 5. What type of voltage does a Hall-effect sensor produce?

Answer Dc 6. Connect the DMM to the sensor output and ground terminals. Allow the sensor to rotate and measure its voltage output with the DMM. Describe the reading on the DMM. Answer Answers will vary but include: fluctuating voltage 7. Why did you get this reading?

Answer Answers will vary but include: signal is too fast for meter to accurately display 8. Why are the resistance and voltage output tests not effective for the Hall-effect?

Answer Answers will vary but include: no meaningful resistance values and signal speed is too fast for meter to accurately display 9. Connect a DSO/GMM to the sensor’s output wire and ground terminals. Rotate the sensor and obtain a waveform. Draw the waveform below.

Answer Answers will vary but include: should show a square wave digital pattern 10. Label the parts of the waveform you obtained.

Answer Answers will vary but include: signal off (ground) rising voltage, signal on-time, falling voltage

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

11. How will the waveform change as the rpm of the sensor increases?

Answer The frequency of the signals will increase.

12. Why do you think Hall-effect sensors are used in place of permanent magnet sensors in some situations?

Answer Answers will vary but include: more accurate than AC signals, voltage is constant

CONCEPT ACTIVITY 26-6 Optical Pickups 1.

Inspect an optical pickup as provided by your instructor. How many output circuits does the pickup have?

Answer Answers will vary but include: 4 to 360 or more

2. How many slits does each part of the pickup have?

Answer Answers will vary but include: 1 to 360 3. How are these slits used?

Answer Answers will vary but include: number 1 TDC location, each degree of crank rotation for misfire monitoring 4. What advantages or disadvantages does the optical pickup have compared to a permanent magnet or Hall-effect sensor?

Answer Answers will vary but include: very accurate, expensive Connect a DSO/GMM to the pickup signal output wire(s). Rotate the sensor and obtain a waveform pattern.

5. Draw the waveform pattern here.

Answer Answers will vary but include: square wave digital pattern

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

6. What type of waveform signal does the optical pickup produce?

Answer Answers will vary but include: square wave digital pattern 7. As the rotation speed increases, how does the waveform change?

Answer Answers will vary but include: frequency increases

CONCEPT ACTIVITY 26-7 Ignition Control Modules Locate the ICM, pickups, and related wiring on several vehicles.

Vehicle 1 Year __________ Make __________ Model __________ Engine __________ Ignition System Type __________ ICM location __________ Pickup type and location __________ Wire colors of pickup to ICM __________ Wire colors of ICM power and ground __________ Answer Answers will vary based on vehicles used.

Vehicle 2 Year __________ Make __________ Model __________ Engine __________ Ignition System Type __________ ICM location __________ Pickup type and location __________ Wire colors of pickup to ICM __________ Wire colors of ICM power and ground __________ Answer Answers will vary based on vehicles used.

1.

What factors do you think affect the location of the ICM?

Answer Answers will vary but include: ease of mounting, cooling capacity

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

CONCEPT ACTIVITY 26-8 Ignition Timing The ignition system has to adjust the firing of the coil based on engine speed and load. As the rpm increases, the amount of time between coil firing events gets shorter. This decreases dwell time. If the dwell becomes too short, the coil will not have enough time to fully charge, and the spark output will be decreased. Figure 26-2 shows how the spark timing must take place sooner as rpm increases. When the ICM advances timing, the process to generate the spark takes place sooner. When the spark generation process takes place later, it is called timing retard.

FIGURE 26–2 As engine speed increases, ignition must begin earlier to end by 23 degrees ATDC. 1.

How would the engine performance be affected if the timing did not advance as engine rpm increased?

Answer reduced power, reduced efficiency

2. Under what conditions does the engine not need as much timing advance?

Answer cruise, deceleration, idle 3. Under what conditions might the powertrain control module (PCM) command the timing retard?

Answer detonation or spark knock

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

In older model vehicles, timing control was achieved by a combination of centrifugal weights and a vacuum diaphragm. The centrifugal weights changed position based on engine speed.

The vacuum diaphragm responded to engine load. Between the two, the ignition timing was able to advance as required, but since both were mechanical in nature, they were susceptible to wear and failure. Modern ignition systems use electronic timing control. The PCM controls timing based on input from various engine sensors.

4. List the sensors used by the PCM to determine timing needs.

Answer Answers may vary but can include: throttle position, engine speed, manifold pressure, engine coolant temperature, intake air temperature

CONCEPT ACTIVITY 26-9 Ignition System Types

FIGURE 26–3 Spark plug firing for a six-cylinder engine with electronic ignition (EI).

1.

What are the advantages of EI and COP systems compared to DI systems?

Answer Increased dwell and saturation, individual cylinder adjustments

2. How many ignition coils does a V6 engine equipped with an EI system have?

Answer Three 3. How many ignition coils does a V8 engine with a COP system have?

Answer Eight

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

Electronic ignition systems operate using a waste spark system. When a coil fires, it fires both of the secondary terminals and both spark plugs connected to that coil. One plug is on the combustion stroke and the other is on the exhaust stroke. The plug on the combustion stroke requires more energy to ignite the air/fuel mixture than the plug on the exhaust stroke.

Because the plugs are in series with each other, one plug fires from positive to negative, and the other fires from negative to positive (Figure 26-3).

4. Why does the plug on the combustion stroke require more voltage than the plug on the exhaust stroke?

Answer The higher pressure in the compression cylinder 5. What can happen if one of the spark plugs or plug wires fails on an EI system?

Answer Both cylinders may be affected.

CONCEPT ACTIVITY 26-10 Spark Plugs Obtain a sample of spark plugs and a DMM from your instructor.

1.

Examine each plug’s physical characteristics. Notice the differences in the threads, fastener size, terminal type, electrode type, and seating area.

Answer Answers will vary but include: different size threads and gaskets

2. Measure the resistance of the plugs from the plug cable terminal to the center electrode. Resistances: Answer Answers will vary but include: 10–1000 ohms 3. Why do the plugs have high resistance?

Answer Answers will vary but include: to increase voltage and decrease interference Examine the plug insulation for damage.

4. What could happen if the insulation is cracked?

Answer Answers will vary but include: misfires due to spark leakage

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

Examine the gap between the center and ground electrodes.

5. How does the spark plug gap affect the plug firing voltage?

Answer Increased gap increases firing voltage, decreased gap decreases voltage 6. What effect would decreasing the plug gap have on the plug’s firing voltage and cylinder performance?

Answer May allow the plug to foul, reduces voltage, may cause a misfire 7. What effect would increasing the plug gap have on the plug’s firing voltage and cylinder performance?

Answer Increases voltage, faster electrode wear

CONCEPT ACTIVITY 26-11 Spark Plug Wires 1.

Use a DMM to measure the resistance of several spark plug wires. Record your results.

Wire 1 resistance _______ Wire 2 resistance _______ Wire 3 resistance _______ Answer Answers will vary but include: 100–5000k ohms

2. Why do spark plug wires have high resistance?

Answer To reduce RFI 3. Inspect the wires for damage to the insulation. Record your findings.

Answer Answers will vary but include: good to damaged 4. What problems can result from damaged plug wire insulation?

Answer Misfires, crossfires

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

CONCEPT ACTIVITY 26-12 Firing Order 1.

Locate the firing order diagrams for three lab vehicles with different engine and ignition types. Record the firing order for each.

Firing order 1 _______ Firing order 2 _______ Firing order 3 _______ Answer Answers will vary but include: 1342, 123456, 153624, 18436572

2. What factors do you think apply to selecting a firing order for an engine?

Answer Balanced power output, vibration, smoothness 3. What could result from the spark plug wires being installed in the wrong firing order?

Answer Misfires, crossfires

CONCEPT ACTIVITY 26-13 Ignition Patterns A primary pattern displays the events occurring in the primary side of the ignition. Figure 26-4 shows the parts of a typical primary pattern. The firing section displays the voltage being used during the spark plug firing event. The coil section shows unused energy being dissipated to ground. Following the coil section is the dwell section.

FIGURE 26–4 A typical primary pattern.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 26: Ignition Systems

The secondary pattern displays the events of the secondary ignition. The firing section shows the voltage required to reach the spark plug gap and the voltage crossing the gap. The intermediate section displays the unused energy dissipating to ground. The dwell section shows the turning on and off of the primary circuit.

1.

Label the parts of the secondary pattern shown in the following figure.

Answer Firing line, spark line, intermediate section, coil section, primary on, primary off 2. What types of faults can be seen in the primary pattern?

Answer Answers will vary but may include primary switching faults, coil faults.

3. What types of faults can be seen in the secondary pattern?

Answer Answers will vary but may include high/low secondary resistance, open plug wires, rich/lean conditions, cylinder turbulence.

4. Faults in the spark plugs and plug wires would be visible in what section of the secondary pattern?

Answer The firing and spark lines.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 27: IGNITION SYSTEM DIAGNOSIS AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 4 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 27-1.......................................................................................................... 7 CONCEPT ACTIVITY 27-2 ......................................................................................................... 7 CONCEPT ACTIVITY 27-3 ......................................................................................................... 8 CONCEPT ACTIVITY 27-4 ......................................................................................................... 8 CONCEPT ACTIVITY 27-5 ........................................................................................................ 10 CONCEPT ACTIVITY 27-6 ........................................................................................................ 10 CONCEPT ACTIVITY 27-7 ........................................................................................................ 11

SHORT ANSWER 1.

Why is the procedure for checking the resistance of a waste spark ignition coil different from the procedures for checking other types of ignition coils?

Answer Ignition coil resistance with a waste spark ignition system is tested slightly differently because there are two secondary terminals instead of one. Connect an ohmmeter to each of the secondary terminals and compare to specifications.

2. Name the three types of trace pattern display modes used on an oscilloscope and give examples of when each mode is most useful.

Answer An oscilloscope may be used to display either parade, raster, or superimposed patterns. The parade pattern is useful to easily compare voltage peak differences from cylinder to cylinder. The raster pattern is used to easily compare the timing of events in the ignition system. A superimposed pattern allows identification of the cylinder whose pattern differs from that of the other cylinders.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

3. List the common types of spark plug fouling and the typical problems each type of fouling indicates.

Answer The common types of spark plug fouling are: • Cold fouling, in which there could be an excessively rich air/fuel mixture. Or the plug might not be firing due to an ignition system fault or a mechanical failure involving the cylinder.

• Wet fouling, in which there is excess oil in the combustion chamber.

• Splash fouling, which occurs after an overdue tune-up, when combustion chamber deposits can foul the new plugs. Avoid high speed driving immediately after a tuneup.

• Gap bridging, in which stop-and-go driving causes carbon deposits to accumulate in the combustion chamber that can melt and bridge the spark plug gap when the engine is placed under load.

• Glazing, caused by high-speed driving and wide-open throttle acceleration.

• Overheating, resulting from incorrect heat range, overadvance timing, excessively lean fuel mixture, cooling system failure, low fuel octane rating, incorrectly installed plugs, or a stuck heat riser valve.

• Turbulence burning, in which overheating can be the problem if premature wear is evident.

• Preignition damage, caused by excessive engine temperatures.

4. List at least two methods of checking the operation of Hall-effect sensors.

Answer A Hall-effect sensor can be tested by using either a logic probe or a lab scope, or with a 12-volt source and a voltmeter.

5. Describe the basic procedure for finding the cause of a no-start problem on an engine equipped with an EI system.

Answer To identify the cause of a no-start condition: 1) Connect a test spark plug to the spark plug wire and ground the spark plug case.

2) Crank the engine and observe the spark plug. If there is a bright, snapping, blue spark, the ignition is working properly.

3) If the spark is weak or there is no spark; check the wiring to and from the PCM. 4) If the power and ground circuits for the PCM are okay, connect a voltmeter from the input (battery) terminal on each coil pack to ground. With the ignition switch on, the voltmeter should read 12 volts. If the voltage is less than that, check the system’s wiring diagram to determine what is included in the coil’s power feed circuit.

5) If battery voltage is present, then check the voltage drop across each of the components and wires to identify the location of an open or high resistance.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

If none is found, check the crankshaft and camshaft position sensors. Both of these sensor circuits can be checked with a voltmeter, ohmmeter, or DSO. If the sensors are receiving the correct amount of voltage and have good low-resistance ground circuits, their output should be a digital or a pulsing voltage signal while the engine is cranking. Compare their resistance readings to specifications. If any readings are abnormal, the circuit needs to be repaired or the sensor needs to be replaced.

6. What is the typical procedure for checking the resistance of the primary winding in an ignition coil?

Answer To check the primary windings, set the ohmmeter to the auto-range mode and connect the meter across to the primary coil (BAT and TACH) terminals. An infinite ohmmeter reading indicates an open winding. Higher than normal readings indicate the presence of excessive resistance. If the measurement is less than the specified resistance, the windings are shorted.

7. What does a slope in the spark line represent?

Answer The spark line represents the voltage required to maintain the spark across a plug’s gap and its length represents the amount of time the spark continues. A change in the resistance inside the cylinder, often due to incorrect fuel mixtures, will affect the slope of the spark line.

8. What happens if one of the ground electrodes of a spark plug with two or more electrodes is closer to the center electrode than the other?

Answer When spark plugs are equipped with more than one ground electrode, if one ground electrode is closer to the center electrode than the other, the spark will occur only at the smallest gap.

9. When a spark plug firing voltage test is performed, all the firing lines are the same, but abnormally low. List three possible causes for these results.

Answer Answers will vary but may include: Low primary voltage, high primary resistance, and/or high secondary resistance.

10. A vehicle with a DI has repeated ignition coil failures. What components should be checked, and why?

Answer Answers will vary but may include: The secondary components, especially the spark plug wires. Increased secondary resistance forces the coil to produce more current, which can shorten coil life.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

MULTIPLE CHOICE 1.

Richer air-fuel mixtures ___. a. decrease the electrical resistance inside the cylinder and decrease the required firing voltage b. increase the electrical resistance inside the cylinder and increase the required firing voltage c. increase the electrical resistance inside the cylinder and decrease the required firing voltage d. have no measurable effect on cylinder resistance Answer: a. Richer air/fuel mixtures decrease resistance and result in a lower firing line.

2. While checking a pickup coil with an ohmmeter, a lower-than-normal reading indicates that the pickup unit is ___. a. shorted b. open c. has high resistance d. none of the above Answer: a. A lower than normal resistance reading indicates there may be a short or other similar problem.

3. A CKP sensor can be checked with all of the following except a(n) ___. a. logic probe b. voltmeter c. ammeter d. lab scope Answer: c. A CKP sensor puts out a very low current that changes little as the voltage signal changes, therefore an ammeter will not accurately check the sensor.

4. Which of the following will cause one or more, but not all, firing lines to be higher than normal? a. High resistance in the spark plug wire b. Faulty fuel injector c. Defective spark plug d. All of the above Answer: d. All of these could cause one or more firing lines to be higher than the others.

ASE-STYLE REVIEW QUESTIONS 1.

The firing lines on an oscilloscope pattern are all abnormally low. Technician A says that the problem is probably low coil output. Technician B says that the problem could be an overly lean air-fuel mixture. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

Answer: a. A lean mixture would result in a higher than normal firing line.

2. While testing the coils in an EI system: Technician A says that an infinite reading means that the winding has zero resistance and is shorted. Technician B says that the primary windings in each coil should be checked for shorts to ground. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Primary coil windings should be checked for shorts to ground. When testing the coil windings for resistance, an infinite reading means an open circuit, not zero resistance, or a short circuit as stated by Technician A. 3. While discussing no-start diagnosis with a test spark plug: Technician A says that if a test light flutters at the coil tach terminal but the test spark plug does not fire when connected from the coil secondary wire to ground with the engine cranking, the ignition coil is defective. Technician B says that if a test spark plug connected to a terminal of a waste spark ignition coil fires when the engine is cranking but the engine does not run, a bad PCM is indicated. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. If a test light connected to the coils tach terminal flutters, but the test spark plug does not fire, the coil has most likely failed. If when testing a waste-spark ignition system, there is spark at the test spark plug but the engine does not start, the ignition system is functioning, but a bad PCM is not necessarily indicated as stated by Technician B. 4. Technician A says that EMI can affect sensor signals. Technician B says that EMI can cause intermittent drivability problems. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. EMI can affect sensor signals and can cause intermittent drivability problems.

5. While discussing waste spark EI systems: Technician A says that a spark plug with too wide of a gap can affect the firing of its companion spark plug. Technician B says that improper spark plug torque can cause an engine misfire. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

Answer: c. Both technicians are correct. High resistance of one spark plug on a wastespark ignition system will affect the companion cylinder. If the spark plugs are not correctly torqued, they may not make good contact with the cylinder head, resulting in increased resistance and a possible misfire.

6. While discussing how to test a Hall-effect crankshaft position sensor: Technician A says that a logic probe can be used. Technician B says that a DMM can be used. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Crankshaft position sensors may be tested with either a logic probe or a DMM. 7. While discussing the possible causes for a no-start condition on an EI-equipped engine: Technician A says that a shorted crankshaft sensor may prevent the engine from starting. Technician B says that a faulty ignition coil may stop the engine from starting. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A is correct because a shorted crankshaft sensor will prevent the ignition control module or engine control module from receiving the rpm reference.

A faulty coil will cause 8. While discussing the diagnosis of an electronic ignition (EI) system in which the crankshaft and camshaft sensor tests are satisfactory but a test spark plug connected from the spark plug wires to ground does not fire: Technician A says that the coil assembly may be defective. Technician B says that the PCM may be faulty. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Either a defective coil or an open circuit in the voltage supply to the coil could result in a no-spark condition.

9. While discussing EI service and diagnosis: Technician A says that the crankshaft sensor may be rotated to adjust the basic ignition timing. Technician B says that the crankshaft sensor may be moved to adjust the clearance between the sensor and the rotating blades on some EI systems. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

Answer: b. Some crankshaft sensors have an adjustable air gap; however, rotating the sensor does not adjust base timing as stated by Technician A. 10. While discussing engine misfire diagnosis: Technician A says that a defective EI coil may cause cylinder misfiring. Technician B says that a shorted CKP could cause a misfire. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. An engine with a continuous misfire should have a compression test.

Defective EI coils can cause a misfire. A shorted CKP will prevent the engine from starting.

TECH MANUAL CONCEPT ACTIVITY 27-1 Identify Ignition Component Wear 1.

Identify the components of the distributor ignition (DI) system that wear and may require service. a. __________ b. __________ c. __________ d. __________ e. __________ f. __________ Answer Distributor cap, rotor, plugs, wires, distributor drive gear, distributor bushing/seals, coil, module

CONCEPT ACTIVITY 27-2 Ignition Coils 1.

What could result from the primary windings’ resistance being too high?

Answer Weak spark, reduced coil output

2. What could result from the resistance of the secondary windings being too high?

Answer Weak spark, reduced coil output

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

3. How can the output of an ignition coil be tested?

Answer With a spark tester 4. What could be symptoms of low coil voltage output?

Answer Answers will vary but may include misfire, rich exhaust, high HC, and/or fouled plugs.

CONCEPT ACTIVITY 27-3 Dwell 1.

Define what dwell represents.

Answer The amount of time current flows through the coil primary

2. How does engine rpm affect dwell?

Answer As rpm increases, dwell time decreases.

3. What could result from too short of a dwell period?

Answer Weak spark, misfire 4. What kind of faults can cause the dwell to be incorrect?

Answer Worn distributor, faulty primary control

CONCEPT ACTIVITY 27-4 Ignition Timing The ignition system has to adjust the firing of the coil based on engine speed and load. On some engines, base timing must be adjusted after servicing the ignition system. Figure 27-1 shows an example of how timing is checked.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

FIGURE 27–1 (A) Timing marks illuminated by a timing light at 10 degrees BTDC; (B) Timing marks at 3 degrees BTDC. 1.

What engine mechanical components can affect the ignition timing?

Answer Distributor, timing belt/chain, distributor drive

2. Describe possible symptoms of an inoperative timing control circuit.

Answer Lack of power, poor fuel economy, increased emissions 3. What could result from ignition timing that is excessively retarded?

Answer Lack of power, poor fuel economy, increased emissions 4. What could result from ignition timing that is excessively advanced?

Answer Ping or spark knock, engine damage © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

CONCEPT ACTIVITY 27-5 Spark Plugs 1.

What type of drivability problem can be associated with faulty spark plugs?

Answer Answers will vary but may include misfire, hard starting, hesitation, increased emissions.

2. What could be the result of installing spark plugs with a heat range that is too hot?

Answer Preignition, plug damage 3. What could be the result of installing spark plugs with a heat range that is too cold?

Answer Fouling, misfire, increased emissions 4. How does a fouled spark plug appear on an ignition scope pattern?

Answer Low firing voltage 5. Why is proper torque on the spark plug necessary?

Answer For proper heat transfer to the cylinder head and proper sealing 6. Explain why spark plugs should not be removed from hot aluminum cylinder heads.

Answer Can damage the threads in the cylinder head

CONCEPT ACTIVITY 27-6 Spark Plug Wires 1.

What can result from open, or high-resistance, spark plug wires?

Answer Misfire, increased emissions, coil failure

2. How does an open spark plug wire appear on an ignition scope pattern?

Answer High firing voltage

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 27: Ignition System Diagnosis and Service

3. How does a shorted spark plug wire appear on an ignition scope pattern?

Answer Low firing line 4. What precautions should be followed when removing and replacing spark plug wires?

Answer Replace with correct type, length, routed properly, connected to correct cylinder

CONCEPT ACTIVITY 27-7 Ignition Patterns 1.

What faults cause high firing lines on the ignition scope pattern?

Answer Open plug wires

2. What faults cause short firing lines on the ignition scope pattern?

Answer Shorted plug wires, fouled plugs 3. What factors affect the spark lines on the ignition scope pattern?

Answer Fuel mixture, cylinder air turbulence

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 28: GASOLINE, DIESEL, AND OTHER FUELS

Table of Contents Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 28-1 ......................................................................................................... 7 CONCEPT ACTIVITY 28-2 ......................................................................................................... 7 CONCEPT ACTIVITY 28-3 ......................................................................................................... 7 CONCEPT ACTIVITY 28-4......................................................................................................... 7

Short Answer 1.

Pump gasoline may contain a small amount of alcohol. Name three problems that can occur if there is an excessive amount of alcohol in gasoline. What percentage of ethanol does E85 contain?

Answer Problems that may result from alcohol in gasoline: • fuel system corrosion • fuel filter plugging • deterioration of rubber fuel system components • lean air-fuel ratio • lack of power • acceleration stumbles • engine stalling • no-start problems • E85 can contain a maximum of 85 percent alcohol.

2. List five advantages the use of piezoelectric injectors has over solenoid-based injectors.

Answer Improved fuel economy, longer life, reduce combustion noise, more precise and rapid control of injection intervals, improved combustion, reduce exhaust emissions, can allow seven or more smaller and staggered sprays of fuel during a single power stroke

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

3. What does the Reid vapor pressure (RVP) test measure?

Answer The Reid vapor pressure test (RVP) measures the volatility of the fuel.

4. List three alternative fuels for an internal combustion engine and briefly explain where they come from.

Answer Some alternative fuels are: 1) Propane (LPG) is a by-product of natural gas production and the petroleum refining process.

2) Ethanol is a fuel made from corn, other grains, or biomass waste.

3) Methanol is a clean-burning fuel that is most often made from natural gas, but can also be produced from coal and biomass.

4) Natural gas, compressed natural gas (CNG) and liquefied natural gas (LNG), is a fossil fuel.

5) Hydrogen is the most abundant element but does not exist as a stand-alone element, therefore it must be produced.

5. Why is the sulfur content in gasoline limited? What is particulate matter and when is it produced?

Answer Some sulfur may be found in refined gasoline. When the sulfur in the fuel is burned, it combines with oxygen to form sulfur dioxide. This compound can combine with water to form sulfuric acid, which is a highly corrosive compound. This acid is the leading cause of exhaust valve pitting and exhaust system deterioration. Sulfuric acid also attacks the linings of the main and rod bearings. With catalytic converters, the sulfur dioxide can cause the obnoxious odor of rotten eggs during engine warm-up. Particulate matter refers to the tiny particles of solid or semisolid material present in the exhaust of a diesel engine. Soot is a natural byproduct of the combustion of diesel fuel.

6. What are oxygenates and why are they added to refined gasoline?

Answer Oxygenates are compounds, such as alcohols and ethers, that contain oxygen. By carrying oxygen, the fuel tends to lean the mixture. Oxygenates improve combustion efficiency, thereby reducing emissions. They also serve as excellent octane enhancers.

7. Name three drivability factors that are affected by the volatility of gasoline.

Answer Cold starting and warm-up, performance at different altitudes, and crankcase oil dilution

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

8. How does SCR lower the NOX content in a diesel’s exhaust?

Answer SCR reduces NOX emissions by injecting a reductant into the exhaust stream over the SCR catalyst. This breaks down the NOX into water vapor and nitrogen (N 2).

9. List 10 products derived from crude oil.

Answer Asphalt, petroleum cokes, grease, lubrication oils, waxes, industrial fuel oil, heating oil, diesel fuel, jet fuel, kerosene, gasoline.

10. Define octane rating.

Answer The octane number of the measure of fuel’s tendency not to experience detonation in the engine. Octane ratings are the motor octane number (MON) and the research octane number (RON).

11. Explain the benefits and disadvantages of E85.

Answer Answers will vary but may include: E85 is produced in the US, no vehicle modifications are required for its use, its emissions are cleaner than those of gasoline, and E85 helps keep the fuel system clean. Disadvantages include a weak infrastructure, it produces less energy by volume than gasoline and fuel economy is decreased.

12. Explain why ultra-low sulfur diesel is required in the United States.

Answer ULSD is much cleaner and engines emit much less NOx and soot.

13. Explain how diesel combustion differs from gasoline engine combustion.

Answer Answers will vary but may include: Diesel engines compress the air in the cylinder so much the air becomes hot enough to ignite with the fuel when the fuel is injected into the cylinder.

Multiple Choice 1.

Which of the following statements about hydro-gen is not true? a. Hydrogen displaces air, so any release in an enclosed space could cause asphyxiation. b. Hydrogen must be stored as a compressed gas. c. Hydrogen is nontoxic.

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

d. Hydrogen is highly flammable and there is risk for an explosion.

Answer: b. Hydrogen may be stored as a compressed gas, as liquid hydrogen, or by bonding it with a substrate such as a metal hydride.

2. Which of the following chemicals is commonly added to gasoline to increase its octane rating? a. Isooctane b. Heptane c. Sulfur d. Ethanol Answer: d. Ethanol is the most commonly used octane booster.

ASE-Style Review Questions 1.

Technician A says that the use of methanol in internal combustion engines has declined over the years. Technician B says that the use of MTBE as a gasoline additive has declined over the years. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The use of both methanol and MTBE has declined.

2. Technician A says that reformulated gasoline produces a leaner air-fuel mixture.

Technician B says that RFG generates more carbon dioxide. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Reformulated gasoline contains more oxygen in order to cause it to generate less carbon monoxide and more carbon dioxide from a leaner air/fuel mixture.

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

3. Technician A says that dedicated vehicles are those designed to use one particular type of fuel. Technician B says that bi-fuel vehicles can operate solely on an alcoholbased fuel or unleaded gasoline, or a mixture of the two, which gives the driver flexibility and convenience when refilling the fuel tank. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: A. Technician A is correct. Bi-fuel vehicles use either natural gas or hydrogen and/or gasoline.

4. Technician A says white smoke in the exhaust of a diesel engine can be the result of a cylinder misfire in a warm engine. Technician B says blue smoke in the exhaust of a diesel engine can be caused by scored cylinder walls. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. White smoke from a diesel can indicate a lean condition, which could cause a misfire. Blue smoke is typically oil burning, which can be caused by scored cylinder walls.

5. Technician A says piezo material is a type of crystal that rapidly shrinks when it is exposed to electrical current. Technician B says piezo material shrinks very slowly when current to it is stopped. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither are correct. Piezo materials expand slightly when electricity is applied.

6. While diagnosing a diesel engine drivability problem: Technician A says that while the scan tool data is similar to that available for a gasoline engine, all diesel engine troubleshooting procedures are unique. Technician B says a cylinder power balance check can be made by checking the resistance of the engine’s glow plugs. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Because gasoline and diesel engines have similar operating conditions and sensors, scan data from both engines will have similar data items. Glow plug resistance will not have any effect on a power balance test.

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

7. While discussing chemicals that are currently added to refined gasoline in order to boost its octane: Technician A says Methylcyclopentadienyl manganese tricarbonyl (MMT) is normally added to gasoline. Technician B says ethanol can be added to boost the octane rating of gasoline. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. MMT and ethanol are commonly used as fuel additives.

8. While discussing common rail fuel injection systems: Technician A says the individual injectors are activated by the high pressure present in the fuel rail. Technician B says some late-model CR systems have an intensifier in the injector that allows for an increase in fuel pressure. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Common rail systems do not rely on fuel pressure to open the injectors, they are controlled by an electronic module.

9. Technician A says diesel engines consume less fuel per mile than a gasoline engine of the same size. Technician B says diesel engines provide more torque than a gasoline engine of the same size. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Diesel engines typically are more fuel efficient as the extract more energy from combustion than gasoline engines. The longer stroke of a diesel engine provides increased torque compared to a gasoline engine of similar displacement.

10. While discussing the reasons why the use of E85 gasoline is good for consumers: Technician A says it is produced in the United States and can reduce our reliance on foreign oil. Technician B says an engine’s fuel consumption is greatly reduced. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. E85 contains less energy by volume than E10 gasoline, so fuel mileage decreases when E85 is used.

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Error! No text of specified style in document.: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 28: Gasoline, Diesel, and Other Fuels

CONCEPT ACTIVITY 28-1 Fuel Additives Match the following gasoline additives with their functions. a. b. c. d. e.

MMT Isopropyl alcohol Phenols Metal deactivators Ethanol

Anti-icing Octane booster (2) Rust inhibitor Oxidation inhibitor

Answer MMT and ethanol – octane boosters; isopropyl alcohol – anti-icing; phenols – oxidation inhibitor; metal deactivators – rust inhibitor

CONCEPT ACTIVITY 28-2 Fuel Octane Requirements 1.

List engine and operating conditions that require the use of high-octane fuels.

Answer Answers may vary but include: high compression, turbo or super charging, higher engine temperatures

2. List any conditions that allow the use of low-octane fuels.

Answer Answers may vary but include: high altitude operation, low compression ratios

CONCEPT ACTIVITY 28-3 Diesel Fuel 1.

List the types of diesel fuel that are available in your area.

Answer Answers will vary but include: number 1 and number 2, off road

2. List the various types of biodiesel that can be used in modern diesel engines.

Answer B100, B10, B5, B2

CONCEPT ACTIVITY 28-4 Alternative Energy

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1.

List some of the alternative energy systems discussed in the textbook under development for automotive use.

Answer Ethanol, methanol, propane/LP gas, compressed natural gas, P-series fuel, hydrogen

2. What are some service and repair differences you foresee for these vehicles?

Answer Answers will vary—differences based on the type of fuel used.

3. What do you think will be the challenges of servicing vehicles in the next 10 years?

Answer Answers will vary—availably of replacement parts.

4. How do you think the use of high-voltage hybrid drive systems will affect you as a service technician?

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 29: FUEL DELIVERY SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 29-1 ......................................................................................................... 7 CONCEPT ACTIVITY 29-2 ......................................................................................................... 7 CONCEPT ACTIVITY 29-3 ......................................................................................................... 8

SHORT ANSWER 1.

List at least five safety precautions that should be adhered to when working with fuel systems.

Answer Safety precautions that should be adhered to when working with fuel systems include: • Always wear eye protection and follow all other safety rules to prevent injury to yourself or others when servicing fuel systems.

• When working on a fuel system in the engine compartment, disconnect the negative cable of the battery. An electrical spark may cause a fire or explosion.

• Slowly remove the fuel filler cap. If the cap is venting vapor or if you hear a hissing sound, wait until it stops before completely removing the cap.

• Do not smoke when working on or near any fuel-related component.

• Do not allow heat or flames to be nearby while working on or near the fuel system.

• Remove all electronic devices, such as cell phones, pagers, and audio equipment, from your clothing when working on or near the fuel system.

• Handle and store all fuels with the utmost caution.

• Clean all fuel spills immediately; spilled fuel may be ignited by hot components.

• If a fuel line or hose is damaged in any way, replace it.

• When disconnecting or reconnecting a fuel line or hose, make sure the mating parts are totally clean.

• After disconnecting a fuel line or hose, plug both ends to prevent dirt from entering.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

•

When disconnecting and reconnecting a fuel line or hose, only use the tools designed for that connection. Using the wrong tool can cause a poor connection that can result in a fuel leak.

2. Describe the operation of the evaporative system integrity check.

Answer Late-model vehicles have a vacuum-based evaporative system integrity check. If the gas cap is loose or missing, the ECM/PCM will detect an evaporative system leak and will illuminate a warning message. A fuel tank pressure (FTP) sensor converts the absolute pressure in the fuel tank into an input for the PCM. The integrity check is done by creating a vacuum in the tank and measuring how well it holds the vacuum. If the gas cap is off or loose, the tank will not hold a vacuum. Before a vacuum is formed in the tank, the canister vent solenoid is closed to seal the entire evaporative system.

Then the vapor management valve creates a slight negative pressure in the tank.

3. Explain the purpose of the relief valve and one-way check valve in an electric fuel pump. What type of fire extinguisher should you have close by when you are working on fuel system components?

Answer The relief valve protects fuel system components from excessive fuel pressure. The one-way check valve prevents fuel from draining from the underhood components and returning to the tank.

There should be a Class B fire extinguisher nearby when working on fuel systems.

4. What is the first thing that should be disconnected when removing a fuel tank?

Answer Before disconnecting and removing a fuel tank, always disconnect the negative battery terminal first.

5. Why is a plastic or metal restrictor placed in either the end of the vent pipe or in the vapor-vent hose on some vehicles?

Answer A restrictor is placed in the vapor-vent hose to control the rate of vapor flow from the tank to the vapor storage tank.

6. Explain why you should relieve fuel pressure before servicing the fuel system.

Answer Answers will vary but may include: Opening a pressurized fuel system will allow fuel to spray out. This can cause personal injury, a fire, or even death.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

7. List two causes of higher-than-normal fuel pressure.

Answer A faulty pressure regulator and an obstruction in the fuel return line.

8. What effect can a restricted fuel filter have on engine performance?

Answer Answers will vary but may include: A restricted fuel filter can decrease pressure and volume, which can cause a lean running condition, misfires, surging, and a no-start.

9. Explain how a returnless fuel system controls fuel pressure.

Answer Answers will vary but may include: The fuel pressure is monitored by the PCM, which controls fuel pump output based on engine operating conditions.

MULTIPLE CHOICE 1.

Most fuel tank filler caps contain a pressure valve and a ___. a. vapor separator b. vacuum relief valve c. one-way check valve d. surge plate Answer: b. Most filler caps contain a pressure valve and a vacuum relief valve.

2. If fuel pump pressure or volume is less than specified, which of the following is not a likely cause of the problem? a. A restricted fuel filter b. A faulty fuel pump c. Restricted fuel return lines d. Restricted fuel supply lines Answer: c. Restricted fuel return lines would most likely cause higher, not lower, pressure.

3. Which of the following statements about a fuel volume test is not true? a. This test measures the flow rate of the pump and can help isolate fuel system restrictions or weak pumps. b. The test is conducted by collecting the fuel dispensed by the certain during a period of time, normally 5 seconds. c. The flow of fuel into the container should be smooth and continuous with no signs of air bubbles. d. Poor results may indicate a bad pump or restrictions in the delivery system.

Answer: b. The test is conducted by collecting the fuel dispensed by the certain during a period of time, normally 30 seconds.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

4. Low fuel pressure can be caused by all of the following except a ___. a. clogged fuel filter b. restricted fuel line c. fuel pump that draws too high amperage d. dirty filter sock in the tank Answer: c. A pump that draws too high amperage is one that is working too hard. Low fuel pressure can be due to a clogged fuel filter, restricted fuel line, weak pump, leaky pump check valve, defective fuel pressure regulator, or dirty filter sock in the tank.

5. If a fuel system loses pressure immediately after the ignition is turned off, the possible problems are all of the following except ___. a. a leaking injector b. restricted fuel lines c. leaking connectors or hoses d. a faulty pressure regulator Answer: b. A lack of residual pressure is typically caused by a leakage problem in an injector, fuel pump, connectors, hoses, or pressure regulator, not a restriction in the fuel lines.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that higher than normal pressure from an electric fuel pump can be caused by a faulty pressure regulator. Technician B says that the typical problem may be an obstructed return line. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Excessive fuel pump pressure can be caused by either a faulty regulator or a restricted return line.

2. Technician A replaces a damaged steel fuel line with one made of synthetic rubber.

Technician B replaces a damaged steel fuel line with one made of steel. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A damaged steel fuel line should be replaced with another steel line.

Replace fuel lines with ones of similar construction.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

3. While discussing electric fuel pumps: Technician A says that some electric fuel pumps are combined in one unit with the gauge sending unit. Technician B says that on an engine with an electric fuel pump, low engine oil pressure may cause the engine to stop running. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Some electric fuel pumps are combined with the sending unit as one assembly. Low engine oil pressure could cause an engine to stop running if it were low enough to result in engine damage, or if the fuel pump is dependent on voltage supply through the oil pressure sending unit contacts because of a failed fuel pump relay.

4. To relieve fuel pressure on an EFI car: Technician A connects a pressure gauge to the fuel rail. Technician B disables the fuel pump and runs the car until it dies. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Fuel pressure may be relieved by attaching a pressure gauge and bleed hose to the fuel rail, or by disabling the fuel pump and running the engine until it dies.

5. While discussing quick-disconnect fuel line fittings: Technician A says that some quick-disconnect fittings may be disconnected with a pair of snap ring pliers.

Technician B says that some quick-disconnect fittings are hand releasable. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Some fuel quick-disconnect fittings are hand releasable, and some require the use of a special disconnect tool, not a pair of snap ring pliers as stated by Technician A. 6. While discussing fuel filters: Technician A says that on some vehicles the fuel filter is not serviceable as a regular maintenance item. Technician B says that some fuel filters are located in the fuel return lines. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Some vehicles do not require periodic fuel filter replacement.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

7. While discussing the various fuel filters used in current automobiles: Technician A says that all systems have a vapor separator that prevents gaseous fuel from being sent to the fuel pump. Technician B says that fuel systems have a strainer located in the fuel tank that prevents large contaminants from entering the fuel system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The strainer is designed to prevent large contaminants from entering the fuel system. Technician A is wrong, the vapor separator is part of the EVAP system not the fuel delivery system.

8. While discussing fuel tank filler pipes and caps: Technician A says that the threaded filler cap should be tightened until it clicks. Technician B says that the vent pipe is connected from the top of the filler pipe to the bottom of the fuel tank. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Threaded fuel caps should be tightened until they click. The vent pipe is connected from the top of the filler pipe to the top of the fuel tank, not the bottom as stated by Technician B. 9. While discussing electric fuel pumps: Technician A says that the one-way check valve prevents fuel flow from the underhood fuel system components into the fuel pump and tank when the engine is shut off. Technician B says that the one-way check valve prevents fuel flow from the pump to the fuel filter and fuel system if the engine stalls and the ignition switch is on. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. The one way check valve prevents fuel from draining back through the pump when the engine is off.

10. While discussing electric fuel pumps: Technician A says that some electric fuel pumps in EFI systems are computer controlled. Technician B says that fuel pump pressure is determined by measuring the amount of fuel that the pump will deliver in a specific length of time. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Some fuel pumps on EFI systems are computer controlled. The amount of fuel a pump will deliver in a specified time period is referred to as fuel pump volume, not fuel pump pressure as stated by Technician B.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

TECH MANUAL CONCEPT ACTIVITY 29-1 Fuel Delivery Systems Examine a vehicle provided by your instructor, and note the following: Year __________ Make __________ Model __________ 1.

Fuel system type __________ Answer Answers will vary but include: gas or diesel

2. Fuel tank construction and location __________ Answer Answers will vary but include: metal or plastic, rear- or mid-mounted 3. Fuel line construction __________ Answer Answers will vary but include: steel, rubber, plastic 4. Fuel filter location __________ Answer Answers will vary but include: no filter, near tank, mid-mounted, underhood 5. Fuel filter and line connection types __________ Answer Answers will vary but include: bolt on, quick connect

CONCEPT ACTIVITY 29-2 Fuel Filler Designs Using vehicles provided by your instructor, examine several gas cap and filler neck designs.

Year __________ Make __________ Model __________ 1.

Cap and filler neck type (threaded or turn and lock) Answer Answers will vary but include: various vehicles

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

Year __________ Make __________ Model __________ 2. Cap and filler neck type __________ Answer Answers will vary but include: various vehicles Year __________ Make __________ Model __________ 3. Cap and filler neck type __________ Answer Answers will vary but include: threaded, capless 4. Do any of these vehicles have a gas cap warning light on the instrument panel?

Answer Answers will vary but include: yes or no 5. What are the problems a faulty gas cap can cause?

Answer An EVAP leak, MIL on

CONCEPT ACTIVITY 29-3 Fuel Filler Designs Using vehicles provided by your instructor, examine several gas cap and filler neck designs.

Vehicle 1 Year __________ Make __________ Model __________ Fuel system type __________ Fuel system operating pressure __________ Method to relieve fuel pressure __________ Answer Answers will vary but include: various vehicle types Answers will vary but include: gas or diesel Answers will vary but include: 40–2200 psi Answers will vary but include: removing fuel pump fuse and running the engine

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 29: Fuel Delivery Systems

Vehicle 2 Year __________ Make __________ Model __________ Fuel system type __________ Fuel system operating pressure __________ Method to relieve fuel pressure __________ Answer Answers will vary but include: various vehicle types Answers will vary but include: gas or diesel Answers will vary but include: 40–2200 psi Answers will vary but include: removing fuel pump fuse and running the engine

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 30: ELECTRONIC FUEL INJECTION

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 30-1 ......................................................................................................... 7 CONCEPT ACTIVITY 30-2......................................................................................................... 7 CONCEPT ACTIVITY 30-3......................................................................................................... 8

SHORT ANSWER 1.

Explain the major differences between port fuel injection and gasoline direct injection systems.

Answer Port fuel injection places the fuel injector in the intake manifold and fuel is directed at the back of the intake valve. Direct injection locates the injector so that fuel sprays into the combustion chamber directly.

2. What is meant by sequential firing of fuel injectors?

Answer Sequential firing of the injectors provides fuel by opening each injector just before the intake valve opens.

3. Explain how the computer controls the air-fuel ratio on an EFI system.

Answer The computer controls the air-fuel mixture in an EFI system based on input from various sensors by varying injector pulse width.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

4. When the throttle plates are closed in a port injection system, where does the air needed for idle speeds come from?

Answer When the engine is at idle and the throttle plates are closed, a small amount of air enters the engine through the idle air orifice. The IAC system allows additional air to enter, if the PCM commands it to do so.

5. Why are special fuel injectors needed for GDI systems?

Answer Special fuel injectors are needed for GDI systems due to much higher injection pressures and the need to seal the injector to prevent heat from igniting the fuel in the injector.

6. How does a GDI system provide for a stratified charge in the combustion chamber?

Answer The placement of the injector tip in the combustion chamber is an important feature of a direct injection system. A small amount of fuel is sprayed near the spark plug when the piston has nearly completed its compression stroke, but before ignition occurs. There is enough fuel around the spark plug to cause combustion. This local area of combustion is the stratified charge.

7. How does a piezoelectric injector work?

Answer Piezoelectric injectors rely on stacked crystals. When voltage is applied to the crystals, they change size. The pintle of the injector is attached to the crystals and when the size of the crystals changes, the pintle moves.

8. Describe clear flood mode and why it is used.

Answer Clear flood mode activates when the driver fully opens the throttle and the engine is cranked. It is designed to shut off the flow of fuel to the injectors in the event the engine is flooded.

9. Explain the basic operation of a CSFI system.

Answer A central multiport fuel injection system (CMFI) combines features from throttle body and port fuel injections system. It has one central injector like a throttle-body system and one poppet nozzle per cylinder like port fuel injection. The central injector is electronically controlled by the PCM; the poppet nozzles are controlled by fuel pressure. CSFI, a similar system, has individual injectors supply fuel to the cylinders through plastic tubes and nozzles that spray the fuel into the intake ports.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

10. Describe how the PCM determines how long to keep the fuel injector open.

Answer Answers will vary but may include: The PCM monitors engine speed, load, temperature, throttle position, oxygen sensors, and other inputs along with its base programming to determine injector opening.

11. Explain how STFT and LTFT modes are used for fuel control.

Answer Answers will vary but may include: STFT is based on pre-catalyst oxygen sensor input and LTFT is based on trends set by the STFT and by the post-catalyst oxygen sensor input. STFT varies constantly during engine operation.

12. Explain the benefits of GDI. Answer Answers will vary but may include: GDI benefits include reduced fuel consumption and the ability to run very lean fuel mixtures during certain operating conditions

MULTIPLE CHOICE 1.

Which type of fuel injection system has the fuel pressure regulator located in the fuel tank? a. Throttle body injection b. Mechanical returnless PFI c. Electronic returnless PFI d. Central multipoint injection Answer: b. A mechanical returnless system places the pressure regulator in the fuel tank.

2. Which of the following statements about fuel trim is not true? a. A positive fuel trim value means that the PCM detects a lean mixture and is decreasing the pulse width to add more fuel to the mixture. b. Short-term fuel trim represents changes made immediately in response to HO2S signals. c. Long-term fuel trim represents changes made to set a new base pulse width. d. Long-term fuel trim responds to the trends of the short-term fuel trim.

Answer: a. A positive fuel trim value means the PCM detects a lean mixture and is increasing the pulse width to add more fuel to the mixture.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

ASE-STYLE REVIEW QUESTIONS 1.

While discussing EFI systems: Technician A says that the PCM provides the proper airfuel ratio by controlling the fuel pressure. Technician B says that the PCM provides the proper air-fuel ratio by controlling injector pulse width. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Air-fuel ratio is controlled by varying injector pulse width.

2. While discussing electronic fuel injection principles: Technician A says that the PCM always adjusts the air-fuel ratio in response to the O2S signals. Technician B says that STFT is based on the output of the O2S signals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The PCM adjusts the air-fuel mixture in response to sensor inputs including the O2 sensor during closed loop operation. Technician B is correct because the PCM changes fuel delivery (STFT) based on the output of the O2 sensor(s).

3. While discussing returnless fuel systems: Technician A says that in a returnless fuel system the pressure regulator is mounted on the fuel rail. Technician B says that in this type of fuel system, the pump and pressure regulator are combined in one unit.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A returnless fuel pressure regulator combines the pump, regulator, and fuel sending unit in the fuel tank, not on the fuel rail as stated by Technician A. 4. While discussing central port injection systems: Technician A says that CPI systems use one injector and several injector nozzles. Technician B says that CPI systems open each injector sequentially. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. This system relies on a single injector with separate nozzles at each cylinder.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

5. While discussing throttle-by-wire systems: Technician A says that a spring on the throttle shaft provides the limp-home feature. Technician B says that most systems have redundant processors and the TP and accelerator pedal sensors send redundant input signals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. As a safety feature, two springs are attached to the throttle plate shaft. One, which is stronger of the two, is used to open the throttle plate slightly if the PCM loses control of engine speed. This allows for limp home operation. The PCM receives multiple signals regarding accelerator pedal and throttle position. Redundancy also occurs in the processing of the inputs and the controlling of the throttle motor. The throttle system is monitored by two separate processors inside the PCM. 6. While discussing the compression ratios used with engines equipped with a GDI system: Technician A says that higher ratios can be used because ignition timing is normally very advanced. Technician B says that higher ratios are possible because the small droplets of fuel injected directly into the cylinder tend to cool the mixture in the cylinder. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Higher compression ratios are possible because the small droplets of fuel injected directly into the cylinder tend to cool the mixture in the cylinder. This cooling makes the mixture denser, which makes the mixture less likely to detonate. Since the fuel is sprayed around the spark plug, the mixture burns quickly. This means there is less need for spark advance, this also decreases the chances of detonation.

7. While discussing air-fuel ratios: Technician A says that a stoichiometric mixture is theoretically the best combination of fuel and air to provide for total combustion.

Technician B says that a stoichiometric mixture always results in complete combustion. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Only Technician A is correct. A stoichiometric mixture is theoretically the best combination of fuel and air to provide for total combustion. The ratio, however, is based on an ideal environment for combustion. This environment rarely exists, and the injection system’s controls vary the ratio in response to the inefficiencies. It also responds to changes in conditions that affect the combustion process.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

8. Technician A says that air-fuel ratios can be regulated by controlling the “on time” of the injectors. Technician B says that the air-fuel ratio can be regulated by controlling the pressure applied to the individual injectors. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. The air-fuel ratio is controlled by adjusting the “on time” of the injector.

9. While discussing GDI systems: Technician A says that this type of system allows engines to run at very lean air-fuel ratios and at higher-than-normal compression ratios. Technician B says that GDI systems eliminate the need to have an EGR valve on the engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. While it is true that GDI systems allow engines to run at very lean air-fuel mixtures and at higher compression ratios, there is still a significant concern over the NOx levels produced by this engine. Basically, due to the heat of combusting lean mixtures. Therefore, they do not eliminate the need for an EGR system that reduces NOx emissions.

10. While discussing SFI systems: Technician A says that when the injection system fires according to crankshaft position and speed, it is operating in the synchronous mode.

Technician B says that one of the advantages of SFI systems is that they are always in the synchronous mode. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. When the system fires according to crankshaft speed, it is called a synchronous system. The action of the injectors is timed to the crankshaft. During starting and acceleration, the PCM may inject extra fuel into all of the cylinders without referring to inputs from the CKP. When the system does this, it is in the asynchronous mode.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

TECH MANUAL CONCEPT ACTIVITY 30-1 Identify Fuel Injection Types 1.

Examine several lab vehicles to determine the type of fuel system they use.

Vehicle 1 Year __________ Make __________ Model __________ VIN __________ Engine Type and Size __________ a. Fuel system type (TBI, MPI, SFI, CPI, GDI): __________ b. How many fuel injectors does the system use? c. Use the service information and record the fuel system pressure. d. Is this a returnless fuel system?

Answer Answers will vary but include: various vehicle types, GDI or PFI, 3–8, 40 psi, yes or no Vehicle 2 Year __________ Make __________ Model __________ VIN __________ Engine Type and Size __________ a. Fuel system type (TBI, MPI, SFI, CPI, GDI): b. How many fuel injectors does the system use? c. Use the service information and record the fuel system pressure. d. Is this a returnless fuel system?

Answer Answers will vary but include: various vehicle types, GDI or PFI, 3–8, 40 psi, yes or no

2. How is correct fuel pressure maintained on a returnless fuel injection system?

Answer Answers will vary but include: using a fuel pressure sensor and modulating fuel pump output 3. How is correct fuel pressure maintained on a fuel return fuel injection system?

Answer Answers will vary but include: using a fuel pressure regulator

CONCEPT ACTIVITY 30-2

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

Injector Pulse-Width Explain how these operating conditions affect injector pulse width.

1. A/C request Answer A/C request—increase pulse width 2. P/S request Answer P/S request—increase pulse width 3. Deceleration Answer Deceleration—decrease pulse width 4. Increased electrical load Answer Increased electrical load—increase pulse width 5. EVAP purge Answer EVAP purge—decrease pulse width 6. EGR flow Answer EGR flow—decrease pulse width

CONCEPT ACTIVITY 30-3 Idle Control Connect a scan tool to an OBD II-equipped vehicle. Navigate to the output controls menu.

Locate the IAC control.

1.

What are the engine’s commanded and actual idle speeds?

Answer Answers will vary but include: 500 rpm

2. What is the throttle position angle or percent?

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 30: Electronic Fuel Injection

Answer Answers will vary but include: 0–10 percent 3. Command the idle speed to increase. Does the engine respond?

Answer Answers will vary but include: yes or no 4. What could be the cause if the engine speed did not increase?

Answer Answers will vary but include: fault with engine computer or throttle body 5. Command the idle speed back to its normal setting.

Answer Answers will vary 6. What could cause the engine’s idle speed to be higher or lower than specified?

Answer Answers will vary but include: induction leaks, carbon build up, throttle body fault

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 31: FUEL INJECTION SYSTEM DIAGNOSIS AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 4 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 31-1 .......................................................................................................... 7 CONCEPT ACTIVITY 31-2.......................................................................................................... 8

SHORT ANSWER 1.

List four service precautions for working on the fuel injection system.

Answer These precautions must be observed when servicing electronic fuel injection systems:

•

Always relieve the fuel pressure before disconnecting any component in the fuel system.

•

Never turn the ignition switch on while any component of the fuel system is disconnected.

• •

Use only the test equipment recommended by the vehicle manufacturer.

• •

When disconnecting the battery, always disconnect the negative cable first.

•

Isolate or disable all high-voltage systems before testing or servicing the fuel system.

When arc welding is necessary, disconnect both battery cables before welding. Also place the ground for the welder as close as possible to the welding electrode or wire to minimize the electrical risk to the modules on the vehicle.

Use a grounding strap to prevent static electric discharges when handling computers, modules, and computer chips.

2. What is indicated by a LTFT reading of 24 percent?

Answer The PCM is adding fuel based on a lean condition.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

3. Describe how testing GDI fuel systems differs from non-GDI systems.

Answer Supply-side pressure can be checked with a pressure gauge but fuel pressure supplied by the high-pressure pump to the injectors is checked with scan tool.

4. What is the difference between the pulse width and the duty cycle of an injector?

Answer Pulse width is the time measured in milliseconds that an injector is energized. Duty cycle is the percentage of on-time to total cycle time.

5. How can you use a dual trace scope to make sure that the injectors are firing at the correct time?

Answer A dual trace lab scope can be used to make sure that the injectors are firing at the correct time. Connect the lab scope so that one trace displays the ignition reference signal and the other trace displays the injector signal. The two signals should have some sort of rhythm between them that should be constant. If the injector’s wave form is fine but varies, a faulty ignition reference sensor or circuit is faulty. If the ignition signal is lost because of a faulty sensor, the injection system will also shut down. If the injector circuit and the ignition reference circuit shut down at the same time, the cause of the problem is probably the ignition reference sensor. If the injector circuit shuts off before the ignition circuit, the problem is the injector circuit or the PCM. 6. What are three possible problems that can allow fuel pressure to rapidly bleed down once the engine is shut off?

Answer A fuel leak, a leaking fuel pressure regulator, a leaking injector, and a faulty fuel pump will cause the fuel pressure to quickly bleed down after the engine is shut off.

7. What is the purpose of having two accelerator pedal signals in an electronic throttle control system?

Answer Depending on the vehicle, there can be two separate APP sensors or one sensor capable of sending two separate signals. One signal is used to define the position of the pedal. The other signal is used to monitor the sensor itself. The PCM compares the two signals and if there is a difference in the reported pedal position, the PCM determines the sensor is bad.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

8. What is indicated by a negative LTFT value?

Answer A negative LTFT value means there is a rich condition that may be caused by leaking injectors or a faulty fuel pressure regulator.

9. What problem may result from dirt buildup on an engine’s throttle plates?

Answer Dirt, gum, or varnish buildup on the throttle plates or throttle body restricts the flow of air into the engine and may result in a drivability problem.

10. What is the difference between STFT and LTFT? Answer OBD-II compliant vehicles use adaptive fuel control strategies referred to as short term fuel trim (STFT) and long-term fuel trim (LTFT) to make adjustments to fuel control calculations. STFT begins when the engine goes into closed loop and the computer begins recognizing input from the O2 sensors. Once the engine reaches a predetermined operating temperature (typically about 180°F), the PCM begins to update the LTFT based on engine speed and STFT. STFT works to bring LTFT close to 0 percent correction. A rich condition will be indicated by a –LTFT number and a lean condition will be indicated by a +LTFT number on the scan tool.

11. What is the purpose of a fuel injector balance test?

Answer Answers will vary but may include: To test each injector’s ability to flow fuel.

12. A signal from an O2 sensor that stays above 800 mV will cause the PCM to do what?

Answer Reduce fuel injector pulse and lean out the fuel mixture.

13. Compare and contrast a traditional O2 sensor and an air/fuel ratio sensor.

Answer Answers will vary but may include: Traditional oxygen sensors produce a voltage based on the oxygen contend in the exhaust. Air/fuel ratio sensors produce a varying current based on the oxygen level in the exhaust.

14. Explain how to test an injector on a gasoline direct injection (GDI) system.

Answer Answers will vary but may include: A GDI injector can be checked for electrical resistance and tested with a scan tool to determine if is delivering fuel.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

MULTIPLE CHOICE 1.

Which of the following is the most likely cause of a lean condition during acceleration and cruising speeds? a. A defective oxygen sensor b. A defective PCM c. A defective ECT sensor d. A defective MAF sensor Answer: d. A defective mass air flow (MAF) sensor can under-report air flow and cause a lean running condition.

2. The PCM checks for a closed throttle plate each time the engine starts. This becomes the base for all throttle settings and can be viewed by looking at the PID with the throttle closed. Which of the following would not cause an abnormal reading and a higher-than-normal idle speed? a. A bad TP sensor b. A bad IAC valve c. Loose or worn throttle plates d. Excessive noise in the TP or related circuits Answer: b. A bad IAC could cause a higher than normal idle speed but it has nothing to do with the closing of the throttle plate.

3. Which of the following would not cause a hard-to-start problem on a PFI engine? a. A defective IAC valve b. A defective oxygen sensor c. A leaking fuel pressure regulator d. Dirty injectors Answer: b. The rest of the choices could cause a hard-starting problem.

ASE-STYLE REVIEW QUESTIONS 1.

While discussing the causes of higher- than-specified fuel pressure: Technician A says that a leaking fuel pressure regulator on a PFI system may cause high fuel pressure.

Technician B says that if the fuel return line is restricted, fuel pressure may be higher than normal. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A restriction in the return line will cause pressure to build up and cause an increase in system pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

2. While discussing IAC valve diagnosis: Technician A says that on some vehicles, a jumper wire may be connected to specific DLC terminals to check the IAC valve operation. Technician B says that if the scan tester indicates zero IAC valve counts, there may be an open circuit between the PCM and the IAC valve. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. On some systems, such as Toyota, a jumper wire may be used at the data link connector during diagnosis. If the IAC counts are zero, there may be an open circuit.

3. While discussing IAC motor removal, service, and replacement: Technician A says that throttle body cleaner may be used to clean the IAC motor internal components.

Technician B says that on some vehicles, IAC motor damage occurs if the pintle is extended more than specified during installation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. If the pintle is extended beyond specifications, it should be retracted before installation to avoid damage. Throttle body cleaner may be used to clean air passages, not the internal components of the motor as stated by Technician A. 4. While discussing injector testing: Technician A says that a defective injector may cause cylinder misfiring at idle speed. Technician B says that restricted injector tips may result in acceleration stumbles. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Anything that affects the flow of fuel can cause misfiring and performance concerns.

5. While discussing airflow sensors: Technician A says that with mass airflow and volume airflow sensor systems, if any air bypasses the sensors, the engine will run lean.

Technician B says that vacuum leaks in a speed density system will decrease injector pulse width. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Air that bypasses a mass air flow sensor causes the engine to run lean because the amount of fuel injected is based on the amount of air flowing through the

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

sensor; additional air that bypasses the sensor leans the mixture. A speed density system with a vacuum leak will increase, not decrease, injector pulse width.

6. While discussing scan tool diagnosis of fuel injection systems: Technician A says that the scan tool may allow for control over some systems and components on many systems. Technician B says that many scan tools will store sensor readings during a road test and then play back the results in a snapshot test mode. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Many scan tools can provide different functions for diagnosing concerns.

7. While discussing a high idle speed problem: Technician A says that higher-than-normal idle speed may be caused by low electrical system voltage. Technician B says that higher-than-normal idle speed may be caused by a defective coolant temperature sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. The engine control module may increase idle speed if certain fault conditions, such as low charging system voltage or incorrect temperature sensor readings occur.

8. While discussing the causes of a rich air-fuel ratio: Technician A says that a rich airfuel ratio may be caused by a faulty fuel rail pressure sensor. Technician B says that a rich air-fuel ratio may be caused by a defective coolant temperature sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. A faulty fuel pressure regulator may allow increased fuel flow and a temperature sensor reading too low can increase fuel delivery.

9. While diagnosing an idle speed problem: Technician A says that higher-than-normal TP signals at idle will cause the IAC to close, which will decrease idle speed. Technician B says that if the resistance of the ECT is too low, a lower-than-normal voltage signal is sent to the PCM, which interprets this as a hot engine and will close the IAC to decrease speed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

Answer: c. Both are correct. Incorrect sensor readings can cause the engine control module to alter the idle speed.

10. While looking at fuel trim values: Technician A says that restricted or dirty injectors may be evident by a negative LTFT. Technician B says that a faulty fuel pressure regulator may result in a negative LTFT. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. If a lean condition caused by a vacuum leak, restricted injectors, dirty MAF, clogged fuel filter, or bad fuel pump exists, the LTFT will have a + number. If the injectors leak or the fuel pressure regulator is faulty, there will be a rich condition. The rich condition will be evident by −LTFT numbers.

TECH MANUAL CONCEPT ACTIVITY 31-1 Fuel Filters Year __________ Make __________ Model __________ Engine Type and Size __________ Fuel System Type __________ 1.

Locate the fuel filter and describe its location.

Answer Answers will vary but include: various makes and models of vehicles Answers will vary but include: under rear- or mid-section of vehicle, underhood

2. What types of connections are used to connect the filter to the lines?

Answer Answers will vary but include: bolt on, quick connects 3. What is the manufacturer’s recommended replacement interval?

Answer Answers will vary but include: 30k to 90k miles 4. What drivability symptoms could a restricted fuel filter cause?

Answer Answers will vary but include: misfire, rough running, lack of power

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

CONCEPT ACTIVITY 31-2 Fuel Filters Year __________ Make __________ Model __________ Engine Type and Size __________ Fuel System Type __________ 1.

How many fuel injectors does this system use?

Answer Answers will vary but include: one or two per cylinder

2. Does this system use a cold-start injector?

Answer Answers will vary but include: yes or no 3. Explain the operation of a fuel injector.

Answer Current flow through the injector coil pulls the plunger back to allow fuel to flow through the injector body.

4. What factors determine the length of the injector pulse width?

Answer Engine load, coolant temperature 5. What is the purpose of the fuel pressure regulator?

Answer To allow for small changes in fuel pressure and increase fuel flow when under load 6. How is the fuel pressure regulated on a returnless system?

Answer Fuel pump pulse-width modulation 7. What can cause fuel pressure to be higher than specified?

Answer Fault vacuum pressure regulator, restricted return

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 31: Fuel Injection System Diagnosis and Service

8. How can higher-than-specified fuel pressure affect engine performance?

Answer Rich fuel mixture 9. How can a faulty fuel pressure regulator affect engine performance?

Answer Can leak and allow fuel to enter via the vacuum hose, can cause incorrect fuel pressure 10. How can lower-than-specified fuel pressure affect engine performance?

Answer Lean fuel mixture 11. Explain how a dirty or restricted fuel filter can affect drivability.

Answer Reduced fuel volume, lean fuel mixture 12. Describe how to test for dirty or restricted fuel injectors.

Answer Injector flow rate, injector rpm power balance test

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 32: INTAKE AND EXHAUST SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 32-1 ......................................................................................................... 7 CONCEPT ACTIVITY 32-2 ......................................................................................................... 8

SHORT ANSWER 1.

What is the difference between psia and psig readings?

Answer When a gauge is designed to read pressures greater than atmospheric pressure, all measurements taken are given in pounds per square inch and should be referred to as psig (pounds per square inch gauge). Gauges and other measuring devices that include atmospheric pressure in their readings also display their measurements in psi.

However the measurements on these gauges should be referred to as psia (pounds per square inch absolute). There is a big difference between 12 psia and 12 psig. 12 psia is less than atmospheric pressure and therefore would represent a vacuum, whereas, 12 psig would be approximately 26.7 psia.

2. Describe two methods to check for a restricted exhaust system.

Answer A vacuum gauge, a scan tool, and/or an exhaust backpressure gauge can be used to check for a restricted exhaust system.

3. What is acoustic supercharging?

Answer When air is drawn into the cylinders, it moves at a high speed. The moving air is suddenly halted by the closing of the intake valve. The air bounces off the closed valve and heads toward the plenum area. When the air reaches the plenum, it meets a rush

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

of incoming air and bounces back toward the intake valve. The air, however, bounces back quicker than it did when it left the intake valve. This is due to a push given by the intake air. The runners in an intake manifold are designed to take the bouncing intake air and send it back to the intake valve in time for the next opening. This timing determines the length of the runner and results in a stronger intake charge since the air is under pressure. In most manifolds, this air wave bounces several times before the intake valve opens again. The bouncing effect and resultant pressure of the air is called acoustic supercharging.

4. Describe the basic operation of an intake manifold runner control (IMRC) system.

Answer IMRC systems are the most commonly used variable intake manifold designs. They change the path of air between long and short runners or between small diameter and large diameter runners according to engine speed. Intake air passes through long or small diameter runners at low speeds and is routed through short or large diameter runners at high speeds. The switching of runners is mostly done by controlling a butterfly valve that opens and closes the short or large diameter runners.

5. Why is an intercooler used on turbocharged and supercharged engines?

Answer An intercooler cools the turbocharged or supercharged air before it reaches the combustion chamber. When intake air is compressed, its temperature increases greatly. As a result, air density is reduced and the cylinders receive less fresh air than what could be from the boosted intake air. Also, the increased temperature of the air increases the chances of engine knock. To offset these consequences, many turbocharger and supercharger systems are fitted with an intercooler or charge air cooler. The removal of heat from the pressurized air going into the intercooler increases the density of the air, which improves efficiency, engine horsepower, and torque.

6. Why is a wastegate not needed on a supercharger?

Answer Unlike a turbocharger, the supercharger does not require a waste gate to limit boost and prevent a potentially damaging overboost condition. Since the speed of the supercharger is directly linked to the engine speed, its pumping power is limited by the rpm of the engine itself rather than revolutions produced by exhaust gases.

Supercharger boost is therefore directly controlled through the opening and closing of the throttle or a bypass system that controls the air leaving the supercharger. The bypass system may be electrically or vacuum controlled.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

7. Why can a restricted exhaust system reduce engine vacuum at 2,000 rpm?

Answer Answers will vary but may include: With a restricted exhaust, the engine cannot push out exhaust gas. This causes pressure to build up in the exhaust, which also backs up into the cylinders when the exhaust valves open. This reduces the engines ability to draw in fresh air and fuel, which decreases the vacuum in the intake.

8. How does a very restricted air filter affect engine efficiency?

Answer Answers will vary but may include: A severely restricted air filter will reduce the amount of air entering the engine and cause the mixture to be rich.

9. List two causes of excessive boost pressure in a turbocharger.

Answer Answers will vary but may include: A faulty wastegate, faulty wastegate control.

10. Contrast the operation of a turbocharger and supercharger.

Answer Answers will vary but may include: Turbochargers are driven by exhaust gases and superchargers are belt driven.

MULTIPLE CHOICE 1.

A mini-converter is used ___. a. on small vehicles where a normal converter will not fit properly b. on engines that use leaded fuels c. in conjunction with EGR systems to supply clean exhaust for the cylinders d. to reduce emissions during engine warmup Answer: d. A mini-converter is sometimes referred to as a warm-up converter because it is used to clean up emissions during warm-up.

2. A restricted exhaust system can cause ___. a. stalling b. loss of power c. backfiring d. all of the above Answer: d. All of the above.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

3. Which of the following is not characteristic of a supercharger? a. It is used to increase engine power by compressing the air that goes into the combustion chambers. b. It usually is located close to the exhaust manifold. c. It utilizes a belt-driven pulley. d. It requires a mechanical connection between the engine and the pressurizing pump to compress the intake gases.

Answer: b. A supercharger requires a mechanical connection to the crankshaft, normally via a belt. It is typically located on top of the engine to avoid heat buildup.

4. Ten psi of turbo boost means that air is being fed into the engine at ___ psia when the engine is operating at sea level. a. 4.7 b. 10 c. 14.7 d. 24.7 Answer: d. Ten psi of turbo boost means that the air entering the engine is 10 psi above atmospheric pressure.

5. What manages turbo output by controlling the amount of exhaust gas entering the turbine housing? a. Wastegate b. Turbine seal assembly c. Turbine d. Compressor Answer: a. The waste gate manages turbocharger output pressure.

6. What is the first step in turbocharger inspection? a. Check the air cleaner for a dirty element. b. Open the turbine housing at both ends. c. Start the engine and listen to the system. d. Remove the ducting from the air cleaner to the turbo and examine the area.

Answer: c. Start the engine and listen to the sound that the turbocharger makes to help diagnose any exhaust or boost pressure leaks.

7. Which of the following statements concerning superchargers is incorrect? a. Superchargers must overcome inertia and spin up to speed as the flow of exhaust gas increases. b. Superchargers do not require a wastegate to limit boost. c. A bypass is designed into the system to allow the supercharger to idle along when extra power is not needed. d. Superchargers improve horsepower and torque.

Answer: a. Superchargers are mechanically driven, rather than being dependent on exhaust gas pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a turbocharger has its own self-contained lubrication system.

Technician B says that a turbocharger should not be operated when the engine’s oil pressure is lower than 30 psi. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Lack of lubrication is a major cause of turbocharger failures.

2. Technician A makes sure that the exhaust system is cool to the touch before working on it. Technician B disconnects the battery’s negative cable before welding an exhaust pipe. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. The exhaust system should be cool and the negative battery cable should be disconnected before working on the exhaust system.

3. Technician A says vacuum refers to any pressure that is greater than atmospheric pressure. Technician B says vacuum changes based on altitude. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Engine vacuum is a term used to define any pressure that is lower than atmospheric pressure. Atmospheric pressure varies with altitude and therefore vacuum does as well.

4. Technician A uses sandpaper to remove carbon deposits from turbocharger wastegate parts. Technician B scrapes off heavy deposits before attempting to clean the unit.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The waste gate should not be cleaned with any abrasive materials. The use of these can cause damage to the valve and allow the turbocharger to be uncontrolled.

5. Technician A says that a vacuum leak results in less air entering the engine, which causes a richer air-fuel mixture. Technician B says that a vacuum leak can cause the engine to run poorly. Who is correct? a. Technician A b. Technician B © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

c. Both A and B d. Neither A nor B Answer: b. A vacuum leak anywhere in the system results in a leaner mixture, not a richer mixture as stated by Technician A. A lean mixture causes poor engine performance.

6. Technician A says that vacuum hose routing for the entire vehicle is illustrated on the underhood decal. Technician B says that this decal illustrates emission system vacuum hose routing. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A vacuum leak causes an engine to run leaner, not richer than normal. An excessively lean condition can lead to detonation and other drivability problems.

7. Before replacing any exhaust system component: Technician A soaks all old connections with penetrating oil. Technician B checks the old system’s routing for critical clearance points. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Penetrating oil should be used on rusted exhaust pipe connections and critical clearance areas should be checked.

8. A vehicle’s intake manifold is warped: Technician A says the manifold may need to be replaced. Technician B says the manifold may be able to be filed flat and reused. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct, however cutting the manifold to make it straight and flat may cause interference problems with other engine components. The manifold should only be machined if the warpage is slight.

9. Technician A says that the catalytic converter is used only to quiet the noise of the exhaust. Technician B says that the catalytic converter is used to alter the contents of the engine’s exhaust. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

Answer: b. A catalytic converter is really only used for one purpose, that being to reduce the amount of pollutants exiting the exhaust system.

10. Technician A says that the exhaust manifold gasket seals the joint between the exhaust manifold and the exhaust pipe. Technician B says that a resonator helps to reduce exhaust noise. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The exhaust manifold gasket seals the connection between the exhaust manifold and the cylinder head.

TECH MANUAL CONCEPT ACTIVITY 32-1 Identify Air Induction Components On a vehicle, locate and identify the components of the air induction system.

1.

Examine the air filter element. Describe its condition.

Answer Answers will vary but include: clean, dirty

2. An excessively dirty air filter can be restrictive to airflow. What can result from restricted or decreased airflow?

Answer On an FI engine, the engine will run very poorly or not at all once the filter is nearly completely restricted or clogged.

3. Inspect the air box for debris. Mice often make nests in air filter housings. Note your findings.

Answer Answers will vary but include: good or dirty 4. Inspect the induction hoses and clamps. Thoroughly check the hoses for signs of cracks. Describe your findings.

Answer Answers will vary but include: good or damaged

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 32: Intake and Exhaust Systems

5. Describe what problems can result from air induction leaks.

Answer Answers will vary but include: incorrect idle speed, rough running, misfires

CONCEPT ACTIVITY 32-2 Inspect Exhaust System For the engine to operate correctly, the exhaust system must be sealed and intact.

1.

Raise a vehicle and inspect the exhaust system from the manifold gasket back to the tailpipe. Note your findings.

Answer Answers will vary but include: system is good or problems are found

2. Lower the vehicle and start the engine. Quickly accelerate the engine a few times and listen for any exhaust leak. Note your findings.

Answer Answers will vary but include: no problems found or exhaust leak is heard 3. With the engine running, place the transmission in gear and listen for any exhaust noises. Note your findings.

Answer Answers will vary but include: no problems found or exhaust rattle or leak is heard Small exhaust leaks can be found by having an assistant block the tailpipe with the engine running. This will cause the exhaust back-pressure to increase. The exhaust will then be forced out of any leak. Obtain your instructor’s permission to perform this test.

Instructor’s Check __________ 4. Results of exhaust leak test: Answer Answers will vary but include: system is good or there is a leak 5. Exhaust leaks can also be found using a smoke machine. Place the outlet of the smoke machine into the tailpipe and begin to induce smoke. If a leak is present, smoke should rise from the area of the leak. Results of smoke test: Answer Answers will vary but include: system is good or a leak is present

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 33: EMISSION CONTROL SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 33-1 ......................................................................................................... 7 CONCEPT ACTIVITY 33-2 ......................................................................................................... 8 CONCEPT ACTIVITY 33-3 ......................................................................................................... 9

SHORT ANSWER 1.

Explain why a small PCV valve opening is adequate at idle speed.

Answer A small PCV opening is adequate at idle speed because the amount of blowby gases in the crankcase is minimal.

2. At what temperature do nitrogen atoms combine with oxygen atoms to form NO X? Answer Nitrous oxides (NOX) begin to form when temperatures in the combustion chamber reach 2,300°F (1,261°C).

3. Describe the operation of a digital EGR valve.

Answer A digital EGR valve contains up to three electric solenoids that control different size orifices and are operated directly by the PCM. When any solenoid is energized, exhaust gas is allowed to flow through the orifice and enter the intake manifold. The PCM can energize one, two, or three solenoids to supply the correct amount of recirculated exhaust gases for optimum control of NOX emissions.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

4. Name the three types of emissions being controlled in gasoline engines.

Answer Gasoline engines must control emissions of HC, CO, and NOX. 5. Describe how a selective catalytic reduction system works.

Answer Selective catalytic reduction is a process where a reductant is injected into the exhaust stream and then absorbed onto a catalyst. The reductant removes oxygen from a substance and combines another substance with the oxygen to form another compound. In this case, oxygen is separated from the NOX and is combined with hydrogen to form water.

6. What types of catalysts are typically used to reduce NOX and to oxidize HC and CO? Answer The catalyst used in the reduction bed is either platinum or rhodium. When NO X is exposed to hot rhodium, oxygen is removed and NOX becomes just N2. The oxidation bed contains platinum and palladium and changes CO and HC to CO 2 and H2O. 7. Why is a PCV system critical to an engine’s durability?

Answer The PCV system improves engine durability by relieving unwanted crankcase pressure and reducing the formation of sludge.

8. What is a catalyst?

Answer A catalyst is something that causes a chemical reaction without being part of the reaction.

9. Rather than relying on the AIR system for extra oxygen in a TWC, what do most latemodel vehicles do to support the oxidation process?

Answer Most late-model vehicles rely on the PCM’s control of the fuel ratio. By toggling between a lean and rich mixture, the extra oxygen from the lean cycles is used by the catalytic converter.

10. Why do the EGR systems on many late-model diesel vehicles include an EGR cooler?

Answer Most manufacturers cool the incoming EGR gases before introducing them the cylinders to reduce the temperature of combustion and therefore reduce the amount of NOX emitted by the exhaust. Most systems with EGR coolers use engine coolant that passes through a separate circuit to cool the recirculated exhaust gases.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

11. Which exhaust emission increases due to complete combustion?

Answer Carbon dioxide increases with complete combustion.

MULTIPLE CHOICE 1.

Which of the following systems is designed to reduce NOX and has little or no effect on overall engine performance? a. PCV b. EGR c. AIR d. EVAP Answer: b. The EGR system is primarily responsible for the reduction of NOX and, when functioning properly, has little effect on overall engine performance.

2. Which of the following components is used to control NO X emissions? a. Charcoal canister b. Air pump c. EGR valve d. PCV valve Answer: c. EGR valves help reduce combustion temperatures, which lowers Nox

emissions.

3. Technician A says EGR valves are post-combustion emission control devices because they use exhaust gas to reduce NOX. Technician B says EGR valves are pre-combustion emission control devices because they reduce combustion temperatures. Who is correct? a. Technician A b. Both A and B c. Technician B d. Neither A nor B Answer: b. Both are correct. Stored fuel vapors are purged to the intake

manifold for burning in the engine when the correct operating conditions have been met.

4. Technician A says an evaporative emission system stores vapors from the fuel tank in a charcoal canister until certain engine operating conditions are present. Technician B says that when the proper conditions are present, fuel vapors are purged from the charcoal canister into the intake manifold. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both A and B.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

5. Which of the following statements about carbon dioxide is not true? a. CO2 levels are highest when the air-fuel ratio is slightly leaner than stoichiometric. b. The production of CO2 is directly related to the amount of fuel consumed; therefore, more fuel-efficient engines produce less CO2. c. To reduce CO2 levels in the exhaust, engineers are working hard to decrease fuel consumption to keep CO2 low. d. The concern for CO2 emissions is one of the primary reasons for the delayed use of alternative fuels for automobiles.

Answer: d. The concern for CO2 emissions is one of the primary reasons for the continued exploration of alternative fuels for automobiles. Most alternative fuels will emit much less CO2 than gasoline or diesel fuel.

ASE-STYLE REVIEW QUESTIONS 1.

While discussing PCV valve operation: Technician A says that the PCV valve opening is decreased at part-throttle operation com-pared to idle operation. Technician B says that the PCV valve opening is decreased at wide-open throttle compared to part throttle. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. The PCV valve opening is smallest at idle and opens further at part and wide-open throttle.

2. While discussing EGR systems with a differential pressure feedback electronic (DPFE) sensor: Technician A says that the DPFE sensor sends a signal to the PCM in relation to intake manifold pressure. Technician B says that the PCM corrects the EGR flow if the actual flow does not match the requested flow. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The PFE sensor sends a signal to the PCM based on exhaust pressure, not intake manifold pressure as stated by Technician A, and the PCM corrects the EGR flow if actual flow does not match requested flow.

3. While discussing evaporative (EVAP) systems: Technician A says that the coolant temperature has to be above a preset value before the PCM will operate the canister purge solenoid. Technician B says that the vehicle speed has to be above a preset value before the PCM will operate the canister purge solenoid. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

Answer: c. Both technicians are correct. Some systems allow canister purge only above a preset speed, and others have a thermal delay so that the canister is not purged until the engine reaches a certain operating temperature.

4. Technician A says that an EGR valve that is stuck open can cause idle problems.

Technician B says that a stuck closed EGR can increase HC emissions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. A faulty EGR valve can cause concerns such as misfires, incorrect idle, and increased HC emissions.

5. While discussing SCR systems: Technician A says that they are used in place of a conventional catalytic converter to reduce NOX, CO, and HC. Technician B says that the most common reductant used in SCR systems is an ammonia-like substance called urea. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Technicians A is wrong because an SCR system is used only to reduce NOX emissions and are used in conjunction with other converters that control other emission levels.

6. While discussing automotive emissions: Technician A says that oxygen emissions are monitored because they are an indication of the completeness of the combustion process. Technician B says that the conditions for minimizing HC emissions are the same as those that cause high NOX emissions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct.

7. Technician A says that during oxidation, as NOX gases pass over the catalyst, the N atoms are pulled from the NOX molecules and are absorbed by the catalyst. The released oxygen atoms then flow through the converter to the second bed. The result of NOX oxidation is pure nitrogen plus oxygen or carbon dioxide. Technician B says that during the reduction phase inside the converter, hydrocarbon and carbon monoxide molecules experience a second combustion. The result of this combustion or oxidation process is water vapor and carbon dioxide. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

Answer: d. Neither is correct. During reduction, as NOX gases pass over the catalyst, the N atoms are pulled from the NOX molecules and are absorbed by the catalyst. The N atoms then combine with other N atoms to form N2 which passes through the converter. The released oxygen atoms then flow through the converter to the second bed. In some converters, if the level of CO in the exhaust is high, the freed oxygen will bind to the CO molecules to form CO2. The result of NOX reduction is pure nitrogen plus oxygen or carbon dioxide. During the oxidation phase inside the converter, hydrocarbon and carbon monoxide molecules experience a second combustion. This occurs because of the presence of oxygen and the temperature of the converter. The result of this combustion or oxidation process is water vapor and carbon dioxide.

8. While discussing PCV systems without a PCV valve: Technician A says that blowby gases are routed into the intake manifold through a fixed orifice tube. The system works the same as if it had a valve, except that the system is regulated only by the vacuum at the orifice and the size of the orifice. Technician B says that VVT systems eliminate the need for a PCV system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician B is wrong. All engines (gasoline and diesel) need some sort of crankcase ventilation, not only for emissions control but also to increase the engine’s durability.

9. While diagnosing the cause of high HC and O2 emissions: Technician A says that the HC may be elevated because of an ignition problem. Technician B says that the O 2 may be elevated because of an ignition problem. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct because both would cause incomplete combustion.

10. While discussing electric exhaust gas recirculation (EEGR) systems: Technician A says that some are air cooled. Technician B says that some are cooled by engine coolant.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Normally, an EEGR valve is water or air cooled.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

TECH MANUAL CONCEPT ACTIVITY 33-1 Emissions Obtain permission from your instructor to perform this experiment.

WARNING: Torches can be very dangerous. Severe burns can result from improper use or carelessness. Follow all safety guidelines regarding the operation of an oxygen-acetylene torch.

Instructor’s Check __________ 1.

Turn on the fuel (acetylene) valve and, using a striker, ignite the torch. Note the color of the flame, the amount of smoke generated, and any solids present from the flame.

Answer Answers will vary but include: blue/white, blue, yellow, orange, smokey

2. Next, turn on the oxygen valve. Note the color of the flame, the amount of smoke generated, and if any solids are present from the flame.

Answer Answers will vary but include: blue/white, blue, yellow, orange, smokey 3. Why do you think there is such a difference between the acetylene-only flame and the oxygen-acetylene flame?

Answer Answers will vary but include: the addition of oxygen increases flame temperature 4. Why do you think the oxygen-acetylene flame creates less smoke?

Answer Answers will vary but include: more thorough combustion 5. What opinion can you form about how the extra oxygen affects combustion?

Answer Answers will vary but include: it increases heat and efficiency

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

CONCEPT ACTIVITY 33-2 Emission Control Devices 1.

Label the following components as evaporative, pre-combustion, or post-combustion emission control devices. a. Exhaust gas recirculation (EGR) valve Answer EGR valve = pre combustion b. Charcoal canister Answer Charcoal canister = EVAP c. Gas cap Answer Gas cap = EVAP d. Positive crankcase ventilation (PCV) valve Answer PCV valve = post combustion e. AIR pump Answer Air pump = post f.

Catalytic converter

Answer Catalytic converter = post g.

Improved piston rings

Answer Improved piston rings = pre

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

h. Electronic spark control.

Answer Electronic spark control = pre i.

Pulse AIR

Answer Pulse air = post j.

Diesel exhaust fluid

Answer Diesel exhaust fluid = post

CONCEPT ACTIVITY 33-3 Emission Control Devices Write the exhaust emission (NOX, CO, CO2, HC) controlled by the devices listed below.

1.

EGR valve Answer EGR valve = NOX

2. Charcoal canister Answer charcoal canister = HC 3. PCV valve Answer PCV valve = HC 4. Air pump Answer AIR pump = HC

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 33: Emission Control Systems

5. Gas cap Answer Gas cap = HC 6. Catalytic converter Answer Catalytic converter = HC, CO, NOX 7. Diesel exhaust fluid Answer Diesel exhaust fluid = NOX

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 34: EMISSION CONTROL DIAGNOSIS AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 8 CONCEPT ACTIVITY 34-1 ......................................................................................................... 8 CONCEPT ACTIVITY 34-2 ......................................................................................................... 8 CONCEPT ACTIVITY 34-3 ......................................................................................................... 8 CONCEPT ACTIVITY 34-4......................................................................................................... 9 CONCEPT ACTIVITY 34-5 ........................................................................................................ 10 CONCEPT ACTIVITY 34-6........................................................................................................ 10

SHORT ANSWER 1.

What will result from too little EGR flow? And what can cause a reduction in the flow?

Answer Too little EGR flow can cause overheating, detonation, and excess NO x. A reduction in EGR flow can be caused by an electronic fault, vacuum leaks, sticking valves, obstructions, or low vacuum.

2. What can result from a charcoal canister that is filled with liquid or water?

Answer A saturated charcoal canister can cause symptoms easily mistaken for other fuel system problems, like rough idle or flooding.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

3. What happens if a PCV valve is stuck in the open position?

Answer A PCV valve stuck in the open condition will allow excess air to flow through the valve, causing a leaner than normal air/fuel mixture. A rough idle or stalling may result from this mixture.

4. Explain why the I/M 240 and similar tests are being replaced by the OBD II system test.

Answer The OBD II system test does not require the use of a dynamometer and the monitoring abilities of OBD II have decreased the need for tailpipe emissions tests.

5. How do you test the operation of a secondary AIR system?

Answer Run the engine at about 1500 rpm with the secondary air system on (enabled). Using an exhaust gas analyzer, measure and record the emission levels. Next disable the secondary air system and continue to allow the engine to idle. Again, measure and record the emission levels in the exhaust gases. The O2 readings should be at least 4% less than they were when the AIR system was enabled. Less than that indicates an AIR problem.

6. List five common causes for high HC emissions.

Answer Excessive HC emissions may be caused by: • Ignition system misfiring.

• Improper ignition timing.

• Excessively lean or rich air/fuel ratio.

• Low cylinder compression.

• Defective valves, guides, or lifters.

• Defective rings, pistons, or cylinders.

• Vacuum leaks.

• Dirty fuel injector.

• Excessive EGR action.

• Defective system input sensor.

7. Describe carbon monoxide (CO) emissions in relation to air-fuel ratio.

Answer CO is a by-product of combustion. It is formed in the engine when there is not enough oxygen to combine with the carbon during combustion. When the engine receives enough oxygen in the mixture, carbon dioxide (CO2) is formed instead of carbon monoxide (CO). Therefore, as the mixture becomes richer, more CO is formed. If combustion does not take place, CO will be low.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

8. Describe how the PCM determines when to purge the EVAP system.

Answer Answers will vary but may include: EVAP purge is based on operating conditions such as ambient temperature, time since engine start, engine speed, vehicle, speed, engine coolant temperature, and others.

MULTIPLE CHOICE 1.

An EGR valve that does not fully close can cause all of the following except ___. a. a no-start b. stalling c. surging d. detonation Answer: d. Detonation is often caused by a lack of EGR flow. An EGR that does not fully close can cause each of the other concerns.

2. Technician A says increases in CO tend to lower NOX emissions. Technician B says an air leak in the exhaust system may be indicated by a low O2 reading without a high CO reading. Who is correct? a. Technician A b. Both A and B c. Technician B d. Neither A nor B Answer: a. Technician A. An increase in CO often means a richer fuel mixture,

which decreases combustion temperature and Nox emissions.

3. Technician A says that if the engine has excessive blowby or the PCV valve is restricted, the crankcase pressure forces crankcase gases through the clean air hose into the air cleaner. Technician B says engines without blowby do not need a PCV system. Who is correct? a. Technician A b. Both A and B c. Technician B d. Neither A nor B Answer: a. Technician A. All engines have some blowby, which requires some

type of EGR system to remove the vapors and prevent leaks and oil in the air cleaner.

4. Technician A says tailpipe O2 readings should be about 15 percent. Technician B says O2 readings should be 0 percent. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

Answer: d. Neither A nor B. Tailpipe O2 emissions should be low, but not 0

percent.

5. Technician A says an inoperative EGR valve will cause a lean air/fuel mixture.

Technician B says an inoperative EGR valve can cause a misfire. Who is correct? e. Technician A f. Technician B g. Both A and B h. Neither A nor B Answer: c. Both are correct. A lack of EGR flow can result in a lean air/fuel

mixture and misfire concerns.

6. A restricted catalytic converter can cause all of the following except ___. a. stalling after the engine starts b. popping or backfiring through the intake manifold c. a drop in engine vacuum d. increased power at high speeds Answer: d. A restricted catalytic converter would decrease, not increase engine power output.

7. Which of the following statements about EVAP systems is not true? a. If the system is purging vapors from the charcoal canister when the engine is running at high speeds, rough engine operation will occur. b. Cracked hoses or a canister saturated with gasoline may allow gasoline vapors to escape to the atmosphere, resulting in gasoline odor in and around the vehicle. c. Rough idle, flooding, and other similar conditions can indicate a saturated canister. d. A vacuum leak in the system can cause starting and performance problems.

Answer: a. If the system is purging vapors from the charcoal canister when the engine is idling or operating at very low speed, rough engine operation will occur.

8. As a catalytic converter begins to deteriorate, the signal from the post-catalyst HO2S becomes ___ the signal of the precatalyst HO2S. a. shorter than b. more like c. larger than d. flatter than Answer: b. When the converter has lost some of its ability to store oxygen, the postcatalyst or downstream HO2S signal begins to switch more rapidly with increasing amplitude and signal length. It starts to look like the signal from the pre-catalyst or upstream HO2S. 9. How much pressure does a typical EVAP pressure tester apply to the system during testing? a. 14 in. Hg b. 14 psi c. 1 in. H2O d. 0.5 psi

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

Answer: d. EVAP leak testers pressurize the system with a very low pressure (14 inches of water or about 0.5 psi).

10. Which of the following exhaust gases is typically not measured during an I/M 240 test? a. HC b. O2 c. NOX d. CO Answer: b. The I/M 240 test measures HC, CO, NOX, and CO2.

11. A vehicle is setting a lean exhaust code and the HO2S data shows the exhaust to be very lean. Technician A says a malfunctioning AIR system may be the cause. Technician B says a clogged EGR may be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A clogged EGR valve will cause an increase in NOX emissions, but will not cause a lean mixture

ASE-STYLE REVIEW QUESTIONS 1.

While discussing the proper way to test a catalytic converter: Technician A says that a pressure gauge can be inserted into the oxygen sensor bore and the backpressure caused by the converter measured. Technician B says that restrictions in the converter can be checked with a vacuum gauge while the engine is being quickly accelerated.

Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Both tests will identify a plugged catalytic converter.

2. While discussing tailpipe emissions and cylinder misfiring: Technician A says that cylinder misfiring causes a significant increase in HC emissions. Technician B says that cylinder misfiring results in a large increase in CO emissions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A misfire allows raw fuel to enter the exhaust stream, increasing HC emissions. When combustion does not take place, CO will be lower, not higher as stated by Technician B. The oxygen from the cylinder that misfired was not used in combustion and is available to form CO2 instead of CO.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

3. While discussing catalytic converter diagnosis: Technician A says that Mode $06 data should be checked. Technician B says that a good converter is evident by low amounts of CO2 in the exhaust. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. A delta temperature test (temperature difference) is a measure of converter efficiency. A good converter will have high, not low, amounts of CO 2 in the exhaust.

4. While discussing EGR valve diagnosis: Technician A says that if the EGR valve does not open, the engine may hesitate on acceleration. Technician B says that if the EGR valve does not open, the engine may detonate on acceleration. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Detonation on acceleration is a symptom of a faulty EGR valve. An EGR valve that is stuck closed would be unlikely to cause a hesitation.

5. While discussing EGR valve diagnosis: Technician A says that a defective throttle position sensor may affect the EGR valve operation. Technician B says that a defective engine cool-ant temperature (ECT) sensor may affect the EGR valve operation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. EGR operation is dependent on both throttle position and operating temperature.

6. When discussing the diagnosis of a positive back pressure EGR valve: Technician A says that with the engine running at idle speed, if a hand pump is used to supply vacuum to the EGR valve, the valve should open at 12 in. Hg of vacuum. Technician B says that with the engine not running, any vacuum supplied to the EGR valve should be bled off and the valve’s diaphragm should not move. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. With the engine idling, you should not be able to build up vacuum with a hand pump, and the valve should not open. Any vacuum supplied to a positive back pressure EGR valve is bled off with the engine not running.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

7. While diagnosing a PCV problem: Technician A says that a stuck open PCV valve will cause a richer than normal air-fuel mixture. Technician B says that oil in the air cleaner assembly can be caused by a restricted PCV hose. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. A PCV valve that is stuck open results in a leaner than normal air/fuel mixture, and oil in the air cleaner assembly can be caused by a restricted PCV valve or system.

8. Technician A says that the AIR system should pump air into the exhaust manifold(s) during engine warmup. Technician B says that the secondary air system check valve can be checked with an exhaust gas analyzer. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Air is typically injected into the exhaust manifolds during engine warmup and an exhaust analyzer can detect the extra oxygen in the exhaust when the system is operating.

9. While discussing PCV system diagnosis: Technician A says that a defective PCV valve may cause rough idle operation. Technician B says that satisfactory PCV system operation depends on a properly sealed engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

10. While discussing EVAP testing: Technician A says that most OEMs recommend that clean, high-pressure shop air be used to pressurize the system to test for leaks.

Technician B says that nitrogen is typically used to drive the smoke through the system when checking the system with a smoke machine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Most OEMs recommend that low-pressure nitrogen be used to pressurize the system to test for leaks.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

TECH MANUAL CONCEPT ACTIVITY 34-1 OBD II Monitors 1.

List the typical OBD II continuous and noncontinuous monitors.

Answer Continuous: misfire, comprehensive component, fuel system. Non-continuous: catalyst efficiency, HO2S, EGR, EVAP, secondary AIR, thermostat

2. Why are some monitors dependent upon the running of another monitor?

Answer The catalyst monitor is dependent upon the HO2S monitor passing since the postconverter HO2S is responsible for determining catalyst efficiency.

CONCEPT ACTIVITY 34-2 OBD II Monitors 1.

What are the main functions of the PCV system?

Answer To remove blowby gasses from the crankcase and return them to the intake stream

2. What exhaust emission can increase if the PCV system does not operate correctly?

Answer HC 3. What are some other problems that can occur if the PCV system does not operate correctly?

Answer Oil leaks, oil in air cleaner

CONCEPT ACTIVITY 34-3 EGR Systems 1.

What is the primary purpose of the EGR system?

Answer To reduce combustion temperatures and NOX emissions

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

2. What problems can result from a malfunctioning EGR system?

Answer High NOX, lean condition, spark knock or pinging 3. Describe three types of EGR valves found on modern engines.

Answer Vacuum operated, positive pressure, negative pressure, solenoid activated, digital

CONCEPT ACTIVITY 34-4 Catalytic Converters 1.

Describe in detail the function of the catalytic converter.

Answer A converter uses certain metals and elements to convert harmful exhaust gases into less harmful gases. HC, CO, and NOX enter the converter and H2O, CO2, N, O2 leave

2. Describe three types of catalytic converters.

Answer Two-way or oxidizing catalysts and three-way catalysts which affect HC, CO, and NOX 3. What materials are used inside of the catalytic converter?

Answer Platinum, palladium, rhodium, cerium 4. How long is the federal catalytic converter warranty?

Answer Eight years 80,000 miles 5. How long must a catalytic converter be kept by a shop after replacement?

Answer Fifteen days

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 34: Emission Control Diagnosis and Service

CONCEPT ACTIVITY 34-5 Secondary Air Injection 1.

How does the secondary air system aid catalytic converter operation?

Answer By injecting air into the middle of the converter, the oxidizing section of the converter can operate more efficiently.

2. What are some problems from an inoperative secondary air system?

Answer Increased HC and CO emissions

CONCEPT ACTIVITY 34-6 Evaporative Emissions 1.

Which emission is reduced by the EVAP system?

Answer HC

2. How does inadequate fuel cap tightening affect the EVAP system?

Answer The system will not be able to adequately purge fuel vapors.

3. Why does the PCM need to accurately know the fuel level in the fuel tank?

Answer Because the EVAP monitor will only run when the fuel level is between certain ranges

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 35: HYBRID VEHICLES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 4 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 35-1 ......................................................................................................... 7 CONCEPT ACTIVITY 35-2 ......................................................................................................... 8 CONCEPT ACTIVITY 35-3 ......................................................................................................... 9

SHORT ANSWER 1.

Define the term “hybrid-electric vehicle.”

Answer Answers will vary but may include: A vehicle that uses two different types of propulsion, such as the internal combustion engine and an electric motor.

2. Explain the differences between a hybrid and a plug-in hybrid vehicle.

Answer Answers will vary but may include: A hybrid uses an ICE and electric motor to increase fuel economy. The electric motor is powered by a battery that is charged by the hybrid system and by regenerative braking. A plug-in hybrid can operate as an electric vehicle for short driving distances and the battery can be recharged using residential current by plugging the vehicle into a charger.

3. What are the basic components of a belt alternator starter hybrid system?

Answer Motor/generator, drive belt, tensioner, and control unit

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

4. What are the main reasons that a mild hybrid consumes less fuel than a conventional vehicle?

Answer A mild hybrid has stop-start, regenerative braking, and electric motor assist available when the engine needs added power to overcome the load.

5. The Prius PHEV offers many advantages over the basic Prius, how is that possible?

Answer The Prius PHEV is based on the base Prius but has a more powerful battery that allows the Prius to operate as a pure EV for longer distances and at higher speeds.

6. In a Toyota Prius, what members of the planetary gearset are connected to the motor/generators and the engine?

Answer In the planetary gear set, the sun gear is attached to MG1. The ring gear is connected to MG2 and the final drive unit in the transaxle. The planetary carrier is connected to the engine’s output shaft.

7. How often must insulated lineman’s gloves be tested and recertified?

Answer Every six months 8. Nearly all hybrids have less powerful engines than typical nonhybrids. What feature of a hybrid provides power to allow the engine to overcome heavy loads?

Answer Hybrids add the electric motor’s power output to that of the engine’s when the vehicle is accelerating or under heavy load.

9. What is the purpose of a typical inverter?

Answer The inverter changes the high DC voltage of the battery to a 3-phase AC voltage for the electric motors.

10. On hybrids with a separate cooling system for the inverter and other electronics, what needs to happen if air is trapped in the cooling system?

Answer To purge the system of air on some hybrids, a scan tool is used to drive the water pump and air is dispelled through a bleeder screw at the top of the inverter.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

11. List five common sense safety rules that should be followed when working on a hybrid vehicle.

Answer Commonsense rules that should be followed when working on a hybrid vehicle: • Always follow the correct procedures for disarming the high-voltage system before performing any service on or near the high-voltage circuits.

• Avoid all orange colored cables, connectors, and wires unless you have disconnected the high-voltage power source and know what you are doing.

• Always precisely follow the correct procedures. If a repair or service is done incorrectly, an electrical shock, fire, or explosion can result.

• Systems may have a high-voltage capacitor that must discharge after the highvoltage system has been isolated. Make sure to wait the prescribed amount of time (about 10 minutes) before working on or around the high-voltage system.

• Move the key and/or key fob a good distance away from the vehicle before starting any service.

• After removing a high-voltage cable, cover the terminal with vinyl electrical tape.

• When working on or near the high-voltage system, even when it is de-powered, always use insulated tools.

• Never leave tools or loose parts under the hood or close to the battery pack. These can easily cause a short.

• Never wear anything metallic, such as rings, necklaces, watches, and earrings, when working on a hybrid vehicle.

• Alert other technicians that you are working on the high-voltage systems with a warning sign such as “high voltage work: do not touch.”

• Keep in mind that the engine can start and stop on its own if it is left in the idle stop mode. Make sure the READY light in the instrument panel is OFF. • If the vehicle needs to be towed into the shop for repairs, make sure it is not towed on its drive wheels. Doing this will drive the generator(s) to work, which can overcharge the batteries and cause them to explode. Always tow these vehicles with the drive wheels off the ground or move them on a flat bed.

• In the case of a fire, use a Class ABC powder type extinguisher or very large quantities of water.

• When checking for trouble codes, if DTC or P3009 are present, make sure you use caution when working on the HV system. P0AA6 indicates there is decreased resistance in the HV insulation and DTC P3009 suggests there is a short in the HV circuit.

• Always wear lineman’s gloves during the process of de-powering and powering the system back up again.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

12. Explain the operational differences between series and parallel hybrids.

Answer Answers will vary but may include: A series hybrid uses a generator to power an electric motor, which is used to drive the vehicle. In a parallel hybrid, the ICE, the electric motor, or both can be used to drive the vehicle.

13. During diagnostics, the DTC P3009 is displayed. What does this indicate?

Answer P3009 suggests there is a short in the HV system.

MULTIPLE CHOICE 1.

After isolating the high-voltage system, what is the minimum time you should wait before beginning to work on or around the hybrid system? a. 1 hour b. 30 minutes c. 15 minutes d. 5 minutes Answer: d. Five minutes is a common wait time.

2. Which of the following statements about the high-voltage circuits in a Honda Hybrid is NOT true? a. All of the high-voltage cables are covered in orange sleeves for easy identification. b. You should always follow the disarming of the high-voltage systems before performing any service work on or near the high-voltage circuits. c. There is a main switch on the instrument panel that is used to disconnect the battery module from the rest of the car. d. There are three large capacitors in the MDM that will take at least 5 minutes to discharge after the switch is turned off.

Answer: c. There is a main battery disconnect but it is not located on the instrument panel.

3. Which of the following is the least likely to decrease fuel consumption of a hybrid vehicle? a. Low-rolling resistance tires b. Increased aerodynamic drag c. Stop-start systems d. Lighter and less powerful engines Answer: b. Increased drag will decrease fuel economy.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says an insulation resistance tester measures voltage. Technician B says an insulation resistance tester measures the effectiveness of a wire’s insulation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. The tester attempts to pass voltage through the insulation to determine the condition of the insulation.

2. When working on a high-voltage system, it is best to keep anyone who is not part of the service away from you and the car by creating a buffer zone around the car.

Technician A makes sure the outside edges of the zone are at least one foot away from the car. Technician B places orange cones to define the outer boundaries of the zone. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Manufacturers may specify a larger area than one foot around the perimeter of the vehicle.

3. Technician A says a mild hybrid has stop-start, regenerative braking, and electric motor assist available when the engine needs added power to overcome the load.

Technician B says a full hybrid has stop-start, regenerative braking, electric motor assist, and can be driven by only electricity. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Mild hybrids do not have the ability to drive in electriconly mode.

4. Technician A says diesel engines can be used in a hybrid powertrain. Technician B says a gasoline engine is normally used in hybrid power-train. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Either type of engine can be used in a hybrid powertrain.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

5. While discussing working on hybrid vehicles: Technician A says to make sure that the high-voltage system is shut down and isolated from the vehicle before working near or with any high-voltage component. Technician B says that when working on or near the high-voltage system, even when it is de-powered, always use insulated tools. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Work on the high-voltage system should be performed following the manufacturers service procedures.

6. While discussing the DC-DC converter used in most hybrids: Technician A says that it changes some of the DC voltage from the battery module to an AC voltage for the electric motors. Technician B says that it provides the power to operate the car’s 12volt electrical system and accessories. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The DC-DC converter drops high voltage down to low voltage to recharge the low-voltage battery.

7. While discussing regenerative braking: Technician A says the regenerative system can completely stop the vehicle in order to generate a maximum amount of electricity.

Technician B says since most hybrids are FWD vehicles, the rear wheels are designed to claim the most kinetic energy. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither are correct. Regenerative breaking typically is used down to a couple of miles per hour, where the service brakes take over to stop the vehicle and regeneration is accomplished using the drive wheels.

8. Technician A says PVE refrigerant oil is commonly recommended for electric A/C compressors. Technician B says PAG refrigerant oil can be used in many electric A/C compressors. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

9. Technician A says Ford hybrid SUVs with 4WD have an additional motor in the rear axle. Technician B says Ford’s Energi models are plug-in hybrids. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. The Energi vehicles have plug-in capability.

10. While discussing the other classifications for the extended range EV, the Chevy Volt: Technician A says it can be called a plug-in hybrid. Technician B says it can be called a parallel hybrid. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. The Volt can be recharged and driven as an electric vehicle before the engine starts.

TECH MANUAL CONCEPT ACTIVITY 35-1 Hybrid Vehicles Of the following new model hybrids, determine whether each is a mild, assist, or full hybrid a. Toyota Prius Answer Prius = full b. Toyota Highlander Answer Highlander = full/assist c. Toyota Camry Answer Camry = full d. Honda Civic Answer Civic = assist/full

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

e. Ford Fusion Answer Ford Fusion = full f.

Ford C-Max Energi Answer Ford C-Max Energi = full

g.

Lexus ES Hybrid Answer Lexus ES hybrid = full

h. Chevrolet Malibu Answer Malibu = assist i.

Chevrolet Volt Answer Chevy Volt = full

j.

Porsche Cayenne S Hybrid Answer Porsche Cayenne S Hybrid = full

CONCEPT ACTIVITY 35-2 Types of Hybrid Drive Systems 1.

Describe the construction and operation of a full hybrid vehicle, such as the Toyota Prius.

Answer Answers will vary but may include the vehicle has the ability to operate in electric only propulsion.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 35: Hybrid Vehicles

2. Describe the construction and operation of an assist hybrid vehicle, such as the Chevrolet Malibu eAssist.

Answer Answers will vary but may include the electric motor assists the ICE and provide auto stop.

3. Describe the construction and operation of a plug-in hybrid vehicle, such as the Toyota Prius Plug-In. Answer Answers will vary but may include the ability to recharge the HV battery by using residential current.

CONCEPT ACTIVITY 35-3 Hybrid Batteries 1.

What color is used on full hybrid vehicles to indicate high-voltage wiring?

Answer Answers will vary but include: orange

2. What color is use on mild hybrid vehicles to indicate high-voltage wiring?

Answer Answers will vary but include: blue 3. Why must high-voltage gloves be worn when servicing a hybrid?

Answer Answers will vary but include: to help prevent electrocution

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 36: ELECTRIC VEHICLES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 36-1 ......................................................................................................... 7 CONCEPT ACTIVITY 36-2 ......................................................................................................... 7

SHORT ANSWER 1.

Why are carbon dioxide emissions a concern?

Answer Although carbon dioxide (CO2) is part of the air vegetation needs to survive. A high concentration of CO2 in the air allows more sunlight to enter the atmosphere than can escape. This traps heat that warms the atmosphere, which can lead to the “greenhouse effect” and cause global warming.

2. List five things a driver of an EV can do to extend the driving range of the vehicle.

Answer To extend driving range and battery life, a driver can: • Keep the voltmeter out of the heavy consumption or yellow zone.

• Avoid high speed driving. Maintain a moderate speed on highways.

• Avoid driving up inclines.

• Avoid frequent speed increases or decreases. Attempt to drive at a steady pace.

• Avoid unnecessary stopping and braking.

• Avoid heavy traffic or traffic jams whenever possible.

• Avoid full throttle acceleration.

• Accelerate slowly and smoothly.

• The vehicle should be well maintained, this includes proper tire inflation pressures, proper brake adjustments, etc.

•

Remove unnecessary weight in the vehicle, which can shorten the driving range.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

3. What makes up the propulsion system in an EV? Answer The propulsion system of an electric vehicle is made up of two primary components: the traction motor that provides the power to rotate the drive wheels and the controller that controls the power output of the motor.

4. What basic factors affect the required time to recharge the battery pack in an EV? Answer The time required to totally recharge a battery pack depends on a number of things.

However, there are three primary things that affect the required time: the current state of charge of the battery pack, the chemicals used in form the cells of the battery, and the type of charger used.

5. There are two basic ways an EV is connected to an external source of electricity for charging: conductive and inductive. What is the difference between the two?

Answer With a conductive coupling, the coupling is plugged into a receptacle on the vehicle where it connects into the wiring for the batteries. The other end of the coupling is connected to a 110-volt or 220-volt outlet or a battery charger. The other type of coupling is called an inductive coupling. This type of coupling uses a paddle that fits into a socket on the vehicle. Rather than transferring the power by a direct wire connection, power is transferred by induction. This is actually a magnetic coupling between the windings of two separate coils, one in the paddle and the other mounted in the vehicle.

6. Why is water control so important to the effectiveness of a PEM fuel cell?

Answer The membrane must be kept wet but the water can freeze in cold weather. The ice can deter the function of the membrane or destroy. Plus water collected in the exhaust of the fuel cell can freeze and cause a plugged exhaust system.

7. Explain what the ratings of kilowatts and kilowatt-hours mean.

Answer A kilowatt (kW) is the international unit to measure power. A kilowatt is 1,000 watts.

One kW equals 1.34 horsepower and 746 watts equals 1 horsepower. Stored electrical energy is stated in kWh. A kilowatt-hour (kWh) is a unit of electrical energy or work, equal to what is accomplished by one kilowatt acting for one hour.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

8. Explain why traditional transmissions are not necessary in most EVs. Answer Answers will vary but may include: The electric motor does not need a transmission or gearing to efficiently drive the vehicle.

9. Describe how a fuel cell generates electricity.

Answer Answers will vary but may include: A fuel cell produces electricity through an electrochemical reaction that combines hydrogen and oxygen to form water.

10. Has the federal government provided an incentive for purchasing an EV? How does this affect the decision to purchase an EV? Answer Answers will vary but may include: By offering tax incentives.

11. Describe the precautions for charging an EV. Answer Answers will vary but may include: Make sure the vehicle is off; make sure the correct charger is being used; never operate the charger with wet hands; never touch the terminals of the charger or vehicle; do not modify the charger or coupler; and make sure water and other foreign materials do not enter the charger connections.

MULTIPLE CHOICE 1.

Which of the statements about hydrogen is true? a. A hydrogen atom is one proton and two electrons. b. Hydrogen is one of the heaviest elements known and is full of energy. c. Fossil fuels are combinations of carbon and hydrogen. d. Hydrogen is produced in a fuel cell when water is broken down into its basic elements.

Answer: c. Fossil fuels are made from hydrocarbons—substances that combine hydrogen and carbon.

2. Which of the following charging standards is used primarily by Nissan? a. Supercharging b. Level 2 CCS c. CHAdeMO d. DCFC Answer: c. CHAdeMO has not been adopted by most of the electric vehicle

manufacturers.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

3. Which of the following statements about charging connections is not true? a. Each type provides a network connection between the charging station and the vehicle. b. Level 1 and Level 2 charging ports are identical except for the amperage rating. c. Level 2 and Level 2 CCS share similar pin configurations. d. Adaptors are required to convert Super-charging ports to Level 2 charging cords.

Answer: b. There is no Level 1 charging port.

4. What is the basic fuel for a fuel cell? a. Hydrogen b. Methanol c. Electricity d. Gasoline Answer: a. Hydrogen is used to power the fuel cell.

5. Which of these factors affect EV battery charging rates and times? a. Battery pack state of charge b. Battery pack capacity c. Charger type d. All of the above Answer: d. All of these factors affect charging rates and times.

6. Which of the following EV systems typically does not require periodic maintenance? a. Heating and air-conditioning b. Brakes c. Electric power steering d. Transmissions and gearboxes Answer: c. There is typically no maintenance for electric power steering systems.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says power is the ability to do work. Technician B says energy is the rate at which work is done. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither are correct. Power is the rate at which is performed and energy describes various means of performing work.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

2. While discussing inductive charging: Technician A says most current EVs use this system because it is safe. Technician B says this method requires that a weatherproof paddle be inserted into the vehicle’s charge port. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Most EV charging is performed with conductive charging, mating several conductors together.

3. Technician A says some EVs use liquid to heat the passenger compartment. Technician B says some EVs use an electric resistance heater with a fan to heat the passenger compartment. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Heat for the passenger compartment can come from several different sources.

4. While discussing charger connections: Technician A says nearly all EVs currently sold in North America have an Level 1 or 2 connector. Technician B says the connector currently used for DC fast charging on Nissan vehicles is based on the CHAdeMO standard. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Most modern Evs have Level 2 CCS or Supercharger connections.

5. Technician A says that a fuel cell produces electricity through an electrochemical reaction that combines hydrogen and oxygen to form water. Technician B says that in a fuel cell, catalysts are used to ignite the hydrogen, causing a release of electrons or electrical energy. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Fuel cells do not ignite the hydrogen.

6. While diagnosing a decreased driving range concern on an EV: Technician A begins by checking the tire pressure and tire type. Technician B inspects under-vehicle covers and shields. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

Answer: c. Both are correct. Incorrect tire type, pressure and missing shields can affect driving range.

7. While discussing controllers in EVs: Technician A says the controller may reverse the current flow to the motor when reverse gear is selected. Technician B says modern controllers adjust motor speed through pulse width modulation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: c. Both are correct. Reversing current flow causes the motor to spin the opposite direction and the amount of current is controlled by how long the pulses are supplied.

8. Technician A says that all EVs recuperate energy through regenerative braking.

Technician B says that all EVs have an auxiliary 12-volt battery. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Some vehicles use voltages other than 12-volts for the low voltage system.

9. Technician A says that gasoline can be used as a source of hydrogen for a fuel cell.

Technician B says that carbon dioxide can be used as a source of hydrogen for a fuel cell. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Gasoline contains hydrocarbons. Carbon dioxide does not and cannot be used to supply hydrogen.

10. While discussing hydrogen: Technician A says that a hydrogen atom has one proton and two electrons. Technician B says that hydrogen is produced in a fuel cell when water is broken down into its basic elements. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: d. Neither are correct. The most common form of hydrogen contains one proton and one electron. Water is produced after hydrogen and oxygen combine in the fuel cell.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 36: Electric Vehicles

TECH MANUAL CONCEPT ACTIVITY 36-1 Electric Vehicles 1.

Make a list of the electric vehicles currently available for sale.

Answer Answers will vary as models change but may include: The Tesla, Toyota Rav 4 ev, Chevy Spark ev, Ford F150 ev, Nissan Leaf

2. Explain the differences between fuel cell, extended range, and battery electric vehicles.

Answer Answers will vary but may include: fuel cell vehicles use hydrogen and a fuel cell stack to generate electricity to drive an electric motor to propel the vehicle. Extended range vehicles have an ICE that generates electricity to power the electric motor, and battery electric vehicles use a battery to power the electric motor.

CONCEPT ACTIVITY 36-2 Battery Charging 1.

Choose an electric vehicle and research the various charging options available for the vehicle.

Answer Answers will vary but include: level 1, level 2, DCFC

2. Compare and contrast the advantages and disadvantages of the different charging systems.

Answer Answers will vary but include: lower power equals longer charge times, higher power stations typically cost more 3. Using the average cost of a kilowatt-hour (kWh) for your location, determine the cost of recharging a fully discharged battery.

Answer Answers will vary but include: $4–$20

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 37: CLUTCHES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 37-1.......................................................................................................... 6 CONCEPT ACTIVITY 37-2 ......................................................................................................... 7 CONCEPT ACTIVITY 37-3 ......................................................................................................... 8 CONCEPT ACTIVITY 37-4 ......................................................................................................... 9

SHORT ANSWER 1.

What is the most common type of pressure plate spring?

Answer A diaphragm spring is most common.

2. What is used to measure clutch pedal play?

Answer A tape measure or ruler can be used to measure clutch pedal play.

3. List four possible causes of clutch slippage.

Answer Answers will vary but may include: worn clutch disc, insufficient pressure plate pressure, oil soaked disc, warped pressure plate, weak spring, or a release bearing contacting and applying pressure to the release levers.

4. Name three types of clutch linkages.

Answer Clutch linkage may be (1) shaft and lever, (2) hydraulic, or (3) cable.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

5. What safety precautions must be taken regarding the dust in the bell housing?

Answer Answers will vary but may include: Use EPA or OSHA approved asbestos cleaning equipment; do not blow or stir up the dust; or wear a respirator.

6. Describe the procedure for checking clutch pedal free travel.

Answer Answers will vary but may include: Measure the free travel with a ruler or tape measure by applying light pressure on the clutch pedal.

MULTIPLE CHOICE 1.

The clutch, or friction, disc is connected to the ___. a. engine crankshaft b. transmission input shaft c. transmission output shaft d. transmission countershaft Answer: b. The friction disc is splined to the transmission input shaft and rotates with it.

2. Torsional coil springs in the clutch disc ___. a. cushion the driven disc engagement rear to front b. are the mechanical force holding the pressure plate against the driven disc and flywheel c. absorb the torque forces d. are located between the friction rings Answer: c. Torsional springs in the clutch disc absorb and dampen torque forces.

3. Which of the following is probably not the cause of a vibrating clutch? a. Excessive crankshaft end play b. Out-of-balance pressure plate assembly. c. Excessive flywheel runout d. Loose flywheel bolts Answer: a. Excessive crankshaft endplay would be unlikely to cause clutch vibrations.

4. When the clutch pedal is released on a hydraulic clutch linkage, the ___. a. master cylinder piston is returned by spring tension b. master cylinder piston is returned by hydraulic pressure c. slave cylinder is returned by hydraulic pressure d. slave cylinder piston does not move Answer: a. When the clutch pedal is released, a spring returns the master cylinder piston to its stop.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

5. When the clutch is disengaged, the power flow stops at the ___. a. transmission input shaft b. driven disc hub c. pressure plate and flywheel d. torsion springs Answer: c. When the clutch is disengaged, power flow stops at the pressure plate and flywheel.

6. Insufficient clutch pedal clearance results in ___. a. gear clashing while shifting transmission b. a noisy front transmission bearing c. premature release bearing failure d. premature pilot bearing failure Answer: c. Insufficient clutch pedal clearance results in premature release bearing failure.

7. Before making a clutch adjustment, it is necessary to ___. a. measure clutch pedal free travel b. lubricate the clutch linkage c. check the hydraulic fluid level d. place the transmission in reverse Answer: a. Measuring clutch pedal free travel is part of adjusting a clutch.

8. The surface of the pressure plate contacts the ___. a. transmission mainshaft b. throwout bearing c. clutch disc d. flywheel Answer: c. The surface of the pressure plate contacts the clutch disc.

9. Which of the following would not cause clutch binding? a. A warped clutch disc b. Improper pedal adjustment c. An oil-soaked clutch disc d. A cracked fire wall Answer: c. An oil-soaked clutch disc normally causes clutch chatter.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that clutch slippage is most noticeable in higher gears. Technician B says that clutch slippage is not noticeable in lower gears. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Clutch slippage is more noticeable in the higher, not the lower, gears.

2. While discussing ways to determine if a pilot bushing is faulty: Technician A says that if it operated quietly, it does not need to be replaced. Technician B says that a careful inspection of the transmission’s input shaft can determine the condition of the pilot bushing. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Inspection of the transmission input shaft can help indicate the condition of a pilot bushing. Listening for the sound of a pilot bushing is not a valid diagnostic procedure.

3. While discussing the different types of pressure plates: Technician A says that coil spring types are commonly used because they have strong springs. Technician B says that Belleville-type pressure plates are not commonly used because they require excessive space in the bell housing. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Coil spring pressure plates are less commonly used than diaphragm pressure plates, which are more compact, not larger, as stated

by Technician B. 4. While discussing the purpose of a clutch pressure plate: Technician A says that the pressure plate assembly squeezes the clutch disc onto the flywheel. Technician B says that the pressure plate moves away from the clutch disc so that the disc can stop rotating. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. The pressure plate presses on and releases the disc when the clutch is released and applied.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

5. Technician A says that an oil-soaked clutch disc can cause clutch chatter. Technician B says that clutch chatter can be caused by loose bell housing bolts. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Fluid contamination and loose components can cause clutch chatter.

6. While discussing different abnormal clutch noises: Technician A says that pilot bushing noises are most noticeable in cold weather and usually occur when the pedal is being depressed and the transmission is in neutral. Technician B says that release bearing noise is most noticeable when the transmission is in neutral and occurs when the clutch pedal is depressed and stops when the pedal is fully released. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Release bearing noise is most noticeable when the pedal is depressed and should stop when the pedal is released.

7. Technician A says that incorrect clutch adjustment can cause premature clutch disc wear. Technician B says that incorrect clutch adjustment can cause premature clutch release bearing wear. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Too little clearance can cause rapid wear of the clutch components by keeping the clutch partially engaged.

8. While discussing the cause of a pulsating clutch pedal: Technician A says that this can be caused by a low fluid level in the hydraulic system. Technician B says that this can be caused by a warped flywheel. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician A is wrong because a low fluid level would cause a soft pedal, excessive pedal travel, or a clutch that fails to completely disengage when the pedal is depressed.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

9. Technician A says that if the hydraulic clutch reservoir is overfilled, the clutch may prematurely wear. Technician B says that if the fluid level is too low, the clutch may not disengage. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Overfilling may keep the clutch applied and too little fluid may not provide enough pressure for the clutch to operate correctly.

10. Technician A says that all manual transmission vehicles have at least one pilot bearing or bushing for the input shaft. Technician B says that the pressure plate always rotates with the input shaft when the engine is running. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither is correct. Most transversely mounted transaxles do not use a pilot bearing. Also, the pressure plate is rotated by the engine’s flywheel whenever the engine is running.

TECH MANUAL CONCEPT ACTIVITY 37-1 Clutch Theory Obtain from your instructor three sheets of paper and a thumbtack. With the paper in a stack, push the tack through all three sheets in the center. With the papers lying flat, grasp the top sheet and spin it on the tack’s axis.

1.

Did the other two sheets spin with the first sheet?

Answer Answers will vary but include: yes or no

2. If not, why not?

Answer Answers will vary but include: lack of friction between the two

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

Pick up the papers and tack so that the tack is horizontal and the papers are vertical; spin the middle sheet.

3. Did all three sheets rotate?

Answer Answers will vary but include: yes or no 4. If not, why not?

Answer Answers will vary but include: lack of friction between the two 5. What would need to be done to the papers for them to all spin together?

Answer Answers will vary but include: clamp them together

CONCEPT ACTIVITY 37-2 Clutch Components Label the parts of the clutch system shown below (Figure 37-1).

Figure 37-1 Identify the clutch system components.

Answer From left to right: flywheel, clutch disc, clutch fork/lever, pressure plate, release bearing, bell housing, clutch fork ball stud

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

CONCEPT ACTIVITY 37-3 Clutch Linkage Clutches are operated by rod and lever, cable, or hydraulic linkage. Rod and lever linkage is similar to the transmission linkage found on many automatic and manual transmission vehicles. Cable systems are similar to parking brake systems. Refer to Chapter 48 for additional information about cable-operated devices. Hydraulic clutch linkage operates the same way as the hydraulic brake system. Refer to Chapters 8 and 48 for additional information.

Examine several vehicles with manual transmission and note the type of clutch linkage system used.

Vehicle 1 Year __________ Make __________ Model __________ Linkage type: __________ Rod and lever __________ Cable __________ Hydraulic Vehicle 2 Year __________ Make __________ Model __________ Linkage type: __________ Rod and lever __________ Cable __________ Hydraulic Vehicle 3 Year __________ Make __________ Model __________ Linkage type: __________ Rod and lever __________ Cable __________ Hydraulic 1.

Why do you think different vehicles uses different types of clutch linkage?

Answer Answers will vary based on vehicles used.

Answers will vary but include: space limitations, leverage, force required

2. What benefits or drawbacks do you see with one linkage type versus another?

Answer Answers will vary but include: cables stretch but are quite, hydraulic systems are easy to use but can leak

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 37: Clutches

CONCEPT ACTIVITY 37-4 Clutch Service Clutch service is typically straightforward. The transmission/transaxle is separated from the engine to gain access to the clutch assembly. The pressure plate and clutch disc are bolted together as an assembly to the flywheel. The release bearing can be attached to the pilot bearing shaft on the transmission/transaxle or be part of the clutch slave cylinder.

1.

Clutch friction material can contain asbestos. Describe what precautions must be taken when servicing the clutch system to avoid exposure to asbestos dust.

Answer Reclaim asbestos dust using approved tools and equipment

2. Describe why a clutch alignment tool is used.

Answer To properly align the clutch disc with the pressure plate and input shaft 3. Describe the problems that can be caused by a misaligned clutch.

Answer Difficult transmission reinstallation 4. Why is the clutch pilot bearing or bushing replaced during clutch replacement?

Answer To ensure proper input shaft to flywheel alignment

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9

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 38: MANUAL TRANSMISSIONS AND TRANSAXLES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 38-1 ......................................................................................................... 6 CONCEPT ACTIVITY 38-2 ......................................................................................................... 7 CONCEPT ACTIVITY 38-3 ......................................................................................................... 9 CONCEPT ACTIVITY 38-4........................................................................................................ 11 CONCEPT ACTIVITY 38-5 ........................................................................................................ 13 CONCEPT ACTIVITY 38-6........................................................................................................ 14

SHORT ANSWER 1.

What determines whether a conventional transmission or a transaxle is used?

Answer Whether a vehicle uses a transmission or a transaxle depends on the type of drive system used, such as whether the differential gearing is included in the same assembly as the transmission, and the location of the drive wheels.

2. Define the purpose of the final drive gears.

Answer A final drive gear is a set of gears that provides an additional torque increase at the wheels, after the torque has passed through the transmission.

3. What does a shift blocking system do, and how does it basically work?

Answer Shift blocking prevents the driver from shifting into second or third gears from first gear, when the engine’s coolant temperature is below a specified degree, the speed of

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

the car is between 12 and 22 mph (20 and 29 km/h), and the throttle is opened less than 35%. Shift blocking helps improve fuel economy. Shift blocking is controlled by the PCM. A “skip shift” solenoid is used to block off the shift pattern from first gear to second and third gears. The driver moves the gearshift from its up position to a lower position, as if shifting into second gear, but fourth gear is selected.

4. Explain the role of shift rails and shift forks in the operation of a transmission or transaxle.

Answer Shift rails and shift forks are used to control the movement of the synchronizers, with each synchronizer being able to engage or disengage two gear ratios by selecting which gear is locked to the mainshaft.

5. Define the term constant mesh.

Answer Answers will vary but may include: Constant mesh means the sets of gears are always in contact or in mesh with each other.

6. Explain the operation of the synchronizer assembly.

Answer The movement of the inserts forces the blocking ring’s coned friction surface against the coned surface of the first speed gear shoulder. When the blocking ring and gear shoulder come into contact, the grooves on the blocking ring cone cut through the lubricant film on the first speed gear shoulder and a metal-to-metal contact is made.

The contact generates substantial friction and heat. This frictional coupling is not strong enough to transmit loads for long periods. As the components reach the same speed, the synchronizer sleeve can now slide over the external clutching teeth on the blocking ring and then over the clutching teeth on the first speed gear shoulder. Power flow is now from the first speed gear, to the synchronizer sleeve, to the synchronizer clutch hub, to the main output shaft, and out to the driveline.

7. Explain why the synchronizer components are made of brass.

Answer A nonferrous metal such as bronze or brass minimizes wear on the hardened steel gear shoulder.

8. Explain the operation of the reverse idler gear.

Answer The reverse idler gear allows the mainshaft to rotate in the opposite direction of the countershaft.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

MULTIPLE CHOICE 1.

Which of the following gear ratios indicates an overdrive condition? a. 2.15:1 b. 1:1 c. 0.85:1 d. None of the above Answer: c. 0.85:1 is an overdrive ratio.

2. Which type of gear develops gear whine at high rotational speeds? a. Spur gear b. Helical gear c. Both a and b d. Neither a nor b Answer: a. Spur gears are noisier at higher speeds.

3. When an idler gear is placed between the driving and driven gears, the driven gear: a. rotates the opposite direction as the drive gear. b. rotates the same direction as the drive gear. c. reduces the torque transfer from the drive gear to the driven gear. d. none of the above.

Answer: b. With an idler gear, the drive and driven gears rotate in the same direction instead of in opposite directions, such as would be the case without an idler.

4. The component used to ensure that the main-shaft (output shaft) and main (speed) gear locked to it are rotating at the same speed is known as a ___. a. synchronizer b. shift detent c. shift fork d. transfer case Answer: a. A synchronizer matches the speed of the mainshaft and the gear selected to be engaged.

5. In a transaxle, the pinion gear on the pinion shaft meshes with the ___. a. reverse idler gear b. ring gear c. countershaft drive gear d. input gear Answer: b. The ring gear is driven by the pinion gear.

6. Which of the following gear ratios provides the highest torque multiplication? a. 0.85:1 b. 2.67:1 c. 5.23:1 d. 0.50:1

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

Answer: c. The other choices have higher ratios that provide less torque multiplication but higher speeds.

7. Technician A says during torque multiplication, a small gear drives a large gear.

Technician B says during overdrive, a small gear drives a large gear. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: a. Technician A. During overdrive, a large gear drives a small gear, which

turns faster than the input gear.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that most transaxles have a countershaft between the main and output shafts. Technician B says that a countershaft is always in motion when the engine is running. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Transaxle designs typically have an input shaft and an output shaft that is driven directly by the input shaft. The countershaft is in motion only when the clutch is engaged while the engine is running.

2. While discussing the various types of transmissions found on today’s vehicles: Technician A says that one type is the sliding gear trans-mission. Technician B says that one type is the sliding collar transmission. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A collar shift transmission is one type of transmission design currently used.

3. Technician A says that the countergear or cluster gear is actually several gears machined out of single piece of iron or steel. Technician B says that the countergear is driven by the clutch gear and drives the mainshaft speed gears. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Counter gears are typically machined out of one piece and are used to drive the mainshaft speed gears.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

4. Technician A says that reverse lamp switches are activated at the transmission/transaxle by the gearshift lever. Technician B says that reverse lamp switches are activated by a sensor at the input shaft. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Reverse lamp switches may be operated by the gearshift lever. Reverse lamp switches are not operated by a sensor on the input shaft.

5. Technician A says that if a single idler gear is used to obtain reverse gear, its size and number of teeth must be used to calculate gear ratios. Technician B says that an idler gear is often used for reverse gear because it causes the output shaft to rotate in the reverse direction of the input shaft. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. An idler gear enables the transmission output shaft to turn in the opposite direction of the input shaft. The size and number of teeth of an idler gear do not affect the gear ratio, only the direction of rotation.

6. Technician A says that in a conventional trans-mission, the speed gears freewheel around the mainshaft until they are locked to it by the appropriate synchronizer.

Technician B says that speed gears are an integral part of the countershaft assembly.

Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. The gears that produce the different speeds freewheel around the mainshaft until they are locked to it.

7. While discussing the power flow through a five-speed transmission while it is in first gear: Technician A says that power enters on the input shaft, which rotates the countershaft that is engaged with first gear. Technician B says that the first gear synchronizer engages with the clutching teeth of first gear and locks the gear to the mainshaft, allowing power to flow from the input gear through the countershaft and to first gear and the mainshaft. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Power flow is through the input shaft and through the gear that is locked to the mainshaft by its synchronizer.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

8. Technician A says that double-cone synchronizers have friction material on both sides of the synchronizer rings. Technician B says that multiple-cone synchronizers are used with larger engines and require a larger transmission housing. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. With multiple-cone synchronizers, the size of the transmission can be reduced. The multiple-cone synchronizers offer a high synchronizer capacity in a smaller package. To obtain the same results in shifting, a single-cone synchronizer would need to have a larger diameter, which would increase the overall size and weight of the transmission.

9. Technician A says that some synchronizer assemblies use frictional material on the blocking rings to reduce slippage. Technician B says that the inside of some blocking rings is shaped like a cone lined with many sharp grooves. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. There are different methods of using friction in synchronizer design.

10. While discussing shift mechanisms: Technician A says that the interlock notches hold the transmission in the selected gear. Technician B says that the detent notches prevent the selection of more than one gear during operation. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither is correct. The interlock notches prevent the selection of more than one gear during operation. And, the detent notches hold the transmission in the selected gear.

TECH MANUAL CONCEPT ACTIVITY 38-1 Gear Ratios Determine the gear ratios of the following sets of gears (Figure 38-1).

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

Figure 38-1 Determine the gear ratios.

Answer a. 2.5:1 b. .67:1 c. .6:1

CONCEPT ACTIVITY 38-2 Gear Ratios Construct a simple gear train, using assorted container lids, such as from a coffee can, a gallon container of coolant, and a quart bottle of oil. Place a rubber band around the circumference of each lid to increase the coefficient of friction of each. Place the lids against each other and secure the lids in their centers with a tack. Place a mark on each lid at points of intersection. Rotate one lid and note the effect on the other lids (Figure 38-2).

Figure 38-2 Determine the gear ratios.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

1.

Record the diameter of the lids.

Lid 1 __________ Lid 2 __________ Lid 3 __________ Answer Answers will vary based on supplies used.

2. Based on the diameter of each lid, determine the gear ratios between the three.

Answer Answers will vary based on supplies used.

Reconfigure the lids so that a different lid is the driving gear and repeat the activity.

3. How did changing the gear positions change the gear ratios?

Answer Answers will vary but include: ratio increased or decreased 4. In an automobile, where might a small gear drive a bigger gear?

Answer Answers will vary but include: in lower gears, 1st, 2nd, 3rd 5. For what reasons would a small gear be used to drive a larger gear?

Answer Answers will vary but include: to achieve torque multiplication 6. Where might a large gear be used to drive a smaller gear?

Answer Answers will vary but include: in higher gears, 5th, 6th 7. For what reasons would a large gear be used to drive a smaller gear?

Answer Answers will vary but include: to achieve overdrive ratios When a small gear drives a larger gear, it is called gear reduction. The larger driven gear will turn at a slower speed than the input gear, but it will be able to apply more torque due to its larger size. When a large gear drives a small gear, it is called overdrive. The smaller gear will turn faster and with less torque than the input. In the engine, a crankshaft gear drives a camshaft gear with twice the number of teeth. This causes the camshaft to rotate at one-half of the crankshaft speed. In a transmission/transaxle, gear reduction ratios are used for torque and acceleration, whereas overdrive ratios are used for high-speed driving and fuel economy.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

8. In a five-speed transmission/transaxle, first, second, and third gears would be which type of gear ratio?

Answer Answers will vary but include: gear reduction 9. In a five-speed transmission/transaxle, fifth gear would be which type of gear ratio?

Answer Answers will vary but include: overdrive ratios

CONCEPT ACTIVITY 38-3 Manual Transmission Component Identification Most rear-wheel drive (RWD) manual transmissions are similar in construction. Identify the main components of the transmission shown in Figure 38-3.

Figure 38-3 Identify the components of the manual transmission. __________ Input shaft Answer c = input shaft __________ Output shaft Answer a = output shaft __________ Counter shaft Answer j = counter shaft

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

__________ Input gears Answer h = input gear __________ First gear Answer e = first gear __________ Second gear Answer f = second gear __________ Third gear Answer g = third gear __________ Fourth gear Answer h = fourth gear __________ Fifth gear Answer d = fifth gear __________ Sixth gear Answer Answers will vary. __________ Reverse gear Answer i = reverse gear __________ Reverse idler Answer b = reverse idler

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

CONCEPT ACTIVITY 38-4 Power Flow Through a Manual Transmission 1.

Use Figure 38-4 below to trace the power flow through the transmission for each gear.

Figure 38-4 Trace the power flow through the transmission.

First gear Answer First gear

21048 cm 04-24

Second gear Answer Second gear

21048 cm 04-25

Third gear

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

Answer Third gear

21048 cm 04-26

Fourth gear Answer Fourth gear

21048 cm 04-27

Fifth gear Answer Fifth gear

21048 cm 04-28

Sixth gear Answer Answers will vary.

Reverse gear

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12

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

Answer Reverse gear

21048 cm 04-29

2. Why is a third gear necessary for reverse? __________ Answer To reverse the direction of the output shaft from its normal direction of rotation 3. Why are the reverse gears spur gears and not helical gears? __________ Answer Reverse gears are not subject to the load and wear of the forward gears nor are they synchronized for shifting while moving

CONCEPT ACTIVITY 38-5 Synchronizer Construction

Synchronizer in neutral position before shift Figure 38-5 A block synchronizer in its neutral position.

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13

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 38: Manual Transmissions and Transaxles

1.

Identify the parts of the synchronizer shown in Figure 38-5.

Answer a. b. c. d. e. f.

Synchronizer sleeve Blocking ring Blocking ring Driven gear Hub Driven gear

2. Why is reverse not synchronized?

Answer Reverse is not meshed when moving so the shafts do not need to synchronize speed.

3. Why are brass and bronze used for synchronizer blocking rings?

Answer So that the brass wears and not dog teeth on the gears.

CONCEPT ACTIVITY 38-6 Dual Clutch Transmissions 1.

Compare the use of dry- and wet-clutch DCT applications.

Answer Answers may vary but may include: wet clutches are housed within a drum and are complete submerged in lubricant. Dry clutches are typically used with smaller, less powerful engines.

2. Explain the basic operation of a DCT. Answer Answers will vary but may include: the DCT is two separate transmissions with odd and even gears. When a gear is selected, the next gear can be readied and set to apply almost instantly.

3. Explain three benefits of using DCTs. Answer Reduced weight, increased performance, increased fuel economy, improved emissions.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 39: MANUAL TRANSMISSION / TRANSAXLE SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 39-1 ......................................................................................................... 7

SHORT ANSWER 1.

After draining gear oil from a transaxle, the technician notices that the oil has shiny, metallic particles in it. What does this indicate?

Answer Shiny metallic particles in the oil indicate internal bearing or gear wear.

2. Explain what problems can result from using the improper lubricant in a manual transmission.

Answer Answers will vary but may include: Hard shifting, gear clash, damage to synchronizers, damage to gears, damage to bearings, noise.

3. List five checks that should be made during the visual inspection of the parts of a transmission/transaxle.

Answer A visual inspection should include (1) checking for lubricant leaks, (2) inspecting the transmission mount, (3) checking the clutch and transmission linkage, (4) checking the transaxle drive axle boots for cracks, deterioration, and damage, and (5) inspecting the constant velocity joints.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

4. List three causes of noise that are not transmission related but may appear to be.

Answer Some noises that appear to be transmission related but are not, include improperly aligned engines, improperly torqued mounting bolts, damaged or missing rubber mounts, cracked brackets, and loose objects in the engine compartment.

5. What tool is often required to remove gears and synchronizer assemblies from the mainshaft?

Answer Use a gear puller to remove gears, bearings, and synchronizer assemblies.

6. List four common causes of hard shifting.

Answer Answers will vary but may include: incorrect transmission lubricant, worn or damaged synchronizers, worn or damaged gear teeth, worn or damaged shift linkage 7. List three possible causes of manual transmission/transaxle noise in neutral.

Answer Worn input shaft bearings, worn release bearing, worn pilot bearing 8. List three possible causes of a transmission/transaxle sticking in gear.

Answer Worn shift rails, worn or damaged shift linkage, worn or damages synchronizer 9. Explain the possible causes of a clicking noise from the transmission/transaxle.

Answer Clicking is caused by damage gear teeth.

10. When removing or installing bearings, where should the force be applied?

Answer When removing or installing bearings using a press, the force should always be applied to the tight bearing race instead of the loose one.

11. List five common sources for transmission fluid leaks.

Answer Common sources for transmission fluid leak are: • An excessive amount of lubricant in the transmission or transaxle. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

• • • • • • • •

The use of the wrong type of gear oil, allowing the oil to foam excessively and leave through the vent.

A loose or broken input shaft bearing retainer.

A damaged input shaft bearing retainer O-ring and/or lip seal.

Loose or missing case bolts.

Case is cracked or has a porosity problem.

A leaking shift lever seal.

Gaskets or seals are damaged or missing.

The drain plug loose.

12. What should you do to properly identify the type of transmission you are working on?

Answer Carefully look for identification numbers. Transmission identification numbers are found either as stamped numbers in the case or on a metal tag held by a bolt head.

Use a service manual to decipher the identification number.

13. List at least five items that are typically removed when removing a transaxle.

Answer Battery ground cable, underhood electrical connectors to transaxle, front wheels, electrical connectors at the wheel brake units, brake calipers, steering knuckles, drive axles, transaxle to engine brackets, speedometer cable, electrical connectors to sensors, gear shift linkage, reverse lamp switch, starter motor, exhaust heat shields, electrical connectors to oxygen sensors, exhaust pipes and catalytic converters, transaxle to engine mount bolts, cross member, and bell housing to engine bolts.

MULTIPLE CHOICE 1.

A rough, growling noise that is heard from a transaxle while it is in neutral with the engine running, the vehicle stationary, and the clutch engaged is a likely indication that there is a problem in the ___. a. transaxle input shaft bearings b. transaxle main (intermediate) shaft bearings c. first/second synchronizer assembly d. pinion and ring gear interaction Answer: a. Damaged input shaft bearings would be the most likely cause.

2. A clicking noise during transmission/transaxle operation may be an indication of ___. a. worn mainshaft (input shaft) bearings b. faulty synchronizer operation c. failed oil seals d. worn, broken, or chipped gear teeth Answer: d. A clicking noise is most likely caused by chipped or damaged gear teeth.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

3. Worn teeth on a speed gear can cause ___. a. gear clash b. hard shifting c. the transmission to shift into a gear d. the gear to jump out Answer: d. Worn teeth on a speed gear can cause the transmission to slip out of a gear.

4. Using a lubricant that is thicker than the specified lubricant can lead to ___. a. the gear to jump out b. hard shifting c. gear lockup d. gear slippage Answer: b. Using the wrong lubricant causes hard shifting.

5. A poorly adjusted shift linkage can cause which of the following problems? a. Gear clash b. Hard shifting c. The gear to jump out d. All of the above Answer: d. All of the above. Misadjusted gear shift linkage can cause noise and

shifting concerns from either too much play or from being too tight.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that the transmission rear seal at the driveline is particularly prone to leak-age. When Technician B pushes up and down on the transmission, he says that the mounts require replacement because the case moves up and down. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. The transmission rear seal is a common source of leaks. Some up-and-down movement of the transmission case is normal; a transmission mount needs replacement when the rubber separates from the metal plate.

2. A noise occurs in forward and reverse gears but not in neutral: Technician A says that the input shaft bearing may be bad. Technician B says that the mainshaft bearing may be bad. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

Answer: b. Technician B is correct. Technician A is describing a failure that would most likely produce noise while the transmission is in neutral. The noise in question is encountered while the transmission is under load and would most likely be related to the output shaft or mainshaft bearings.

3. A rough, growling noise occurs when a vehicle with a manual transmission is moving in any gear: Technician A says that the rear input shaft bearing may be at fault.

Technician B says that this condition indicates the countergear bearings may be faulty.

Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. When the vehicle is moving, the countershaft gears and bearings are loaded.

4. A car jumps out of gear into neutral, particularly when decelerating or going down hills: Technician A checks the shift lever and external gearshift linkage first. Technician B says that the clutch pilot bearing could be the problem. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Worn linkage or a worn pilot bearing can cause enough play in the transmission input shaft to allow it to pop out of gear.

5. While diagnosing a noise from a transmission: Technician A says that the noise is caused by something internal if it is most noticeable during a test drive. Technician B says that the noise is caused by the clutch if it disappears when the clutch is disengaged. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. A test drive can uncover a variety of nontransmission related noises. If the noise disappears when the clutch is disengaged, it is most likely in the transmission, not in the clutch.

6. Technician A says that broken or worn engine and transaxle mounts can cause a transaxle to have shifting problems. Technician B says that poor shift boot alignment can cause a transaxle to jump out of gear. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

Answer: c. Both are correct. Worn mounts can allow the transmission to move, causing play or strain on the shift linkage and a misaligned shifter can cause the transmission to jump out of gear.

7. Technician A says that shims may be used to adjust shaft end play. Technician B says that snap rings may be used to adjust shaft end play. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. End play can be adjusted in different ways depending on transmission design.

8. During a test drive, a noise that appears to be transmission related disappears when the driver brings the vehicle to a stop and disengages the clutch with the engine at idle. Technician A says that the noise may be caused by an internal transmission problem. Technician B says that the problem may be something interfering with the flywheel or pressure plate. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. Under this condition, the gears and bearings inside the transmission have stopped rotating, causing the noise to disappear. The conditions have not changed the operation of the flywheel and pressure plate; they are still rotating with the engine.

9. While inspecting the synchronizers of a transaxle: Technician A says that if the clutch teeth of the synchronizer are rounded, the synchronizer assembly must be replaced.

Technician B says that the movement of the synchronizer sleeve on the shaft should be checked. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. If the synchronizer dog teeth are rounded, the synchronizer should be replaced. The synchronizer sleeve moves on the hub, not on the shaft.

10. Technician A says that the proper fluid level for a transmission is normally to the bottom of the filler hole. Technician B says that low lubricant levels can cause a transmission to clash during shifting. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 39: Manual Transmission/ Transaxle Service

Answer: c. Both are correct. Typically fill amount is to the bottom of the check/fill plug opening. Low fluid level can affect synchronizer operation and cause gear noise.

TECH MANUAL CONCEPT ACTIVITY 39-1 Preliminary Transmission/Transaxle Inspection 1.

Inspect all powertrain mounts for wear and excessive movement. How can worn or loose powertrain mounts affect transmission/transaxle operation?

Answer Answers will vary but include: movement can pull on shift cables or bind driveshafts

2. Inspect the transmission/transaxle linkage for looseness, binding, or damage. What problems are caused by faults with the linkage?

Answer Answers will vary but include: not going into gear, coming out of gear 3. Ensure the engine is running properly and smoothly.

Answer Answers will vary.

4. Verify proper operation of the clutch components. Explain how faulty clutch operation could affect the operation of the transmission/transaxle.

Answer Answers will vary but include: faulty clutch operation can cause grinding gears when trying to shift 5. Inspect FWD half-shafts for wear, looseness, and damage. Check RWD drive shafts for missing balance weights. Drive shafts are covered more thoroughly in Chapter 40.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 40: DRIVE AXLES AND DIFFERENTIALS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 40-1 ......................................................................................................... 6

SHORT ANSWER 1.

Name the three ways in which CV joints can be classified.

Answer CV joints may be classified by (1) position, (2) function, or (3) design.

2. What type of axle housing resembles a banjo?

Answer An axle with a removable carrier resembles a banjo; sometimes its housing is called the banjo housing.

3. What type of axle merely supports the vehicle load and provides a mounting place for the wheels?

Answer An axle that merely supports the weight of the vehicle and provides a mounting place for the wheels is called a dead axle, as compared to a driving axle, which is called a live axle.

4. What type of floating axle has one wheel bearing per wheel on the outside of the axle housing?

Answer A floating axle with only one bearing per wheel located outside of the axle housing is classified as a three-quarter floating axle. The axle shaft only supports 25% of the weight; the rest is supported by the axle housing.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

5. How are problems normally first noticed with the differential and drive axles?

Answer Differential problems usually appear as either a noise or a leak.

6. What type of final drive gearset requires timing?

Answer A non-hunting gearset 7. How is rear axle shaft end play adjusted?

Answer Changing shims 8. What is an inclinometer used for?

Answer Answers will vary but may include: To measure driveshaft angle.

MULTIPLE CHOICE 1.

In front-wheel drivetrains, the CV joint nearer the transaxle is the ___. a. inner joint b. inboard joint c. outboard joint d. both a and b Answer: d. The inner joint is usually referred to as the inboard joint.

2. A CV joint that is capable of in-and-out movement is a ___. a. plunge joint b. inboard joint c. fixed joint d. both a and c Answer: a. The plunge joint can move in and out as well as operate at an angle.

3. The double-offset CV joint is typically used in applications that require ___. a. higher operating angles and greater plunge depth b. lower operating angles and lower plunge depth c. higher operating angles and lower plunge depth d. lower operating angles and greater plunge depth Answer: a. A double-offset joint has greater plunge capacity and can operate at larger operating angles.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

4. Which type of joint has a flatter design than any other? a. Double-offset b. Disc c. Cross groove d. Fixed tripod Answer: c. A cross-groove joint is flatter than other plunge joint designs.

5. Which of these is the best way to determine which CV joint is faulty? a. Squeeze test b. Runout test c. Visual inspection d. Road test Answer: d. To determine which CV joint is noisy, spin the shaft at different operating angles.

6. The single Cardan/Spicer universal joint is also known as the ___. a. cross joint b. four-point joint c. both a and b d. neither a nor b Answer: c. A single Cardan joint is also called a four-point or a cross joint.

7. The drive shaft component that provides a means of connecting two or more shafts together is the ___. a. pinion flange b. U-joint c. yoke d. biscuit Answer: c. The yoke is used to connect two or more shafts together.

8. Large cars with long drive shafts often use a double-U-joint arrangement called a ___. a. Spicer style U-joint b. constant velocity U-joint c. Cleveland style U-joint d. none of the above Answer: b. A double-Cardan is a constant velocity type U-joint.

9. Which type of driving axle supports the weight of the vehicle? a. Semifloating b. Three-quarter floating c. Full-floating d. None of the above Answer: a. Semifloating axle designs carry the weight and transmit torque to the wheel.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

10. Which of the following describes the double-Cardan universal joint? a. It is most often installed in front-engine rear-wheel drive luxury automobiles. b. It is classified as a constant velocity U-joint. c. A centering ball socket is inside the coupling yoke between the two universal joints. d. All of the above.

Answer: b. Double-Cardan universal joints, found mostly on RWD luxury cars, use a centering ball socket and two universal joints and are commonly called constantvelocity joints.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a gear tooth pattern identifies excessive ring gear runout.

Technician B says that gear patterns are not accurate if there is excessive ring gear runout. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. The recommended method for identifying ring gear runout is with a dial indicator, not with a gear tooth pattern. When ring gear runout is excessive, the resulting gear tooth pattern is inaccurate.

2. Technician A says that limited-slip differential clutch packs are designed to slip when the vehicle turns a corner. Technician B says that a special additive is placed in the hypoid gear lubricant to promote clutch pack slippage on corners. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Limited slip clutches will slip at a predetermined amount of torque while cornering and often use a special lubricant or additive for the clutches.

3. Technician A says that side-bearing preload limits the amount the differential case is able to move laterally in the axle housing. Technician B says that adjusting backlash sets the depth of the mesh between the ring and pinion gears’ teeth. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Both preload and backlash must be checked and set properly for proper operation and reduced wear.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

4. Technician A says that a hunting gearset is one in which one drive pinion gear tooth contacts only certain ring gear teeth. Technician B says that a partial nonhunting gearset is one in which one pinion tooth contacts only six ring gear teeth. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. With a hunting gearset, one pinion gear tooth would contact each of the ring gear teeth. An example of a partial nonhunting gearset is one in which each pinion gear tooth would contact the same six ring teeth instead of the three it would normally contact if it were a nonhunting gearset.

5. While discussing the possible causes for a clunking noise during acceleration: Technician A says that an outer CV joint could be the cause. Technician B says that runout in the drive axle may be the cause of the problem. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Clunking during acceleration and deceleration is normally caused by excessive play in the inboard joint.

6. While diagnosing the cause of a clicking noise that is heard only when the car is turning: Technician A says that the most probable cause is a worn wheel bearing.

Technician B says that the most probable cause is a worn outboard CV joint. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A bad wheel bearing will create a humming noise that disappears or decreases in intensity when the wheels are turned.

7. Technician A says that some axle shafts are retained in the housing by a plate and bolts. Technician B says that a C washer or clip retains some axle shafts in the housing. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

8. Technician A says that when a car is moving straight ahead, all differential gears rotate as a unit. Technician B says that when a car is turning a corner, the inside differential side gear rotates slowly on the pinion, causing the out-side side gear to rotate faster.

Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Driving in a straight line, the differential turns as a unit.

During turns, the outside gear rotates faster as that wheel travels a greater distance than the inside wheel.

9. While discussing different types of ring and pin-ion gearsets: Technician A says that with a non-hunting gearset, each tooth of the pinion will return to the same tooth space on the ring gear each time the pinion rotates. Technician B says that when a hunting gearset rotates, any pinion gear tooth is likely to contact each and every tooth on the ring gear. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Hunting gearsets allow all pinion gear teeth to contact all ring gear teeth during operation. Non-hunting gearset teeth will only contact certain teeth on the ring gear.

10. While reviewing the procedure for setting backlash: Technician A says that backlash is adjusted along with side-bearing preload by loosening or tightening side-bearing adjusting nuts. Technician B says that normally, to decrease the amount of backlash, a thin shim is installed on one side of the gear and a thick one on the other side. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Backlash may be adjusted either with shims or by adjustment nuts.

TECH MANUAL CONCEPT ACTIVITY 40-1 Identifying CV Joints Identify the six basic types of constant-velocity joints shown in Figure 40-1.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

Type: __________

Type: __________

Type: __________

Type: __________

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 40: Drive Axles and Differentials

Type: __________ Figure 40-1 Six types of inboard and outboard constant velocity joints.

Answer Rzeppa joint, inner bolt mounted joint Double offset joint Inner tripod joints Cross-groove joint

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 41: AUTOMATIC TRANSMISSIONS AND TRANSAXLES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 41-1 .......................................................................................................... 6 CONCEPT ACTIVITY 41-2 ......................................................................................................... 7 CONCEPT ACTIVITY 41-3 ......................................................................................................... 9

SHORT ANSWER 1.

Explain the difference between rotary and vortex fluid flow in a torque converter.

Answer Rotary flow of oil in the torque converter is the flow of oil around the circumference of the converter as it rotates around its axis. Rotary flow begins to occur when the speed of the turbine is near the speed of the impeller, or near coupling speed. Vortex flow is the flow of oil from the impeller to the turbine and back to the impeller, at a 90degree angle to engine rotation. The oil from the turbine to the impeller is redirected by the stator during torque multiplication. Maximum vortex flow occurs during maximum torque multiplication and is described as spiraling its way around the converter.

2. What component keeps the stator assembly from rotating when driven in one direction and permits rotation when turned in the opposite direction?

Answer The overrunning clutch is responsible for allowing the stator to rotate in only one direction.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

3. When a transmission is described as having two planetary gearsets in tandem, what does this mean?

Answer When two planetary gearsets are used in tandem, there are two simple planetary units connected in series, as compared to a compound planetary gearset that shares components.

4. Explain the operation of a CVT. Answer A CVT has no fixed gears. Instead of relying on planetary or helical gearsets to provide drive ratios, a CVT uses belts and pulley. One pulley is the driven member and the other is the drive. Each pulley has a movable face and a fixed face. When the movable face moves, the effective diameter of the pulley changes. The change in effective diameter changes the effective pulley (gear) ratio. A steel belt links the driven and drive pulleys. The gear ratio varies with engine speed and temperature.

5. Explain the differences between the three major types of planetary gearsets used in modern automatic transmissions/transaxles.

Answer Answers will vary but may include: Simpson gearsets uses common sun gears; Ravigneaux gearsets use common ring gears; and a Lepelletier gearset combines a basic planetary gearset and a Ravigneaux set.

6. What effect does a 20 °F increase in operating temperature have on the automatic transmission fluid?

Answer It can decrease ATF life by half.

7. Explain the purpose and operation of the TCC. Answer Answers will vary but may include: to reduce the slippage inherent to the torque converter, to reduce engine speed and increase fuel economy 8. How can shift feel be controlled?

Answer “Shift feel” is controlled by the pressure at which each reaction member is applied or released, the rate at which each is pressurized or exhausted, and the relative timing of the apply and release of the members.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

9. What determines the timing of the shifts in an automatic transmission?

Answer Shift timing is determined by throttle pressure and governor pressure acting on opposite ends of the shift valve. Shift valves control the up and downshifting of the transmission by controlling the flow of pressurized fluid to the apply devices that engage the different gears 10. Why must hydraulic line pressures increase when there is an increase of load on the engine?

Answer When the engine is operating under heavy load conditions, fluid pressure is increased to increase the holding capacity of a reaction member and upshifts are delayed.

MULTIPLE CHOICE 1.

To achieve a slow overdrive in a simple planetary gearset, the ___. a. sun gear must be the input member b. ring gear must be the input member c. planetary carrier must be the input member d. ring gear must be held Answer: c. When the carrier is the input, the planetary gearset produces overdrive.

When the carrier is the input and the ring gear is held, maximum, not minimum (slow) overdrive is achieved.

2. In a simple planetary gearset, when the planetary carrier is held, the gearset produces a ___. a. reverse b. direct drive c. fast overdrive d. forward reduction Answer: a. When the carrier is held, a planetary gearset produces reverse.

3. Overrunning clutches are capable of ___. a. holding a planetary gear member stationary b. driving a planetary gear member c. both a and b d. neither a nor b Answer: c. Overrunning clutches are used to either hold a planetary gear member stationary or drive one.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

4. In the coupling stage of conventional torque converter operation, ___. a. both the impeller and turbine are turning at essentially the same speed b. both the stator and turbine are stationary c. both the stator and impeller are stationary d. the stator turns with the turbine and impeller Answer: a. At cruising or coupling speeds, the stator is unlocked and spinning freely.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that bearings that take radial loads are called Torrington washers.

Technician B says that bearings that take axial loads are called thrust washers. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. An axial load is controlled by thrust washers.

2. Technician A says that rotary oil flow is the oil flow around the circumference of the torque converter caused by the rotation of the torque converter on its axis.

Technician B says that the vortex flow is caused by the rotation of the torque converter on its axis. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Rotary flow is correctly described.

3. Technician A says that a stator aids in directing the flow of fluid from the impeller to the turbine. Technician B says that a stator is equipped with a one-way clutch that allows it to remain stationary when necessary. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct.

4. Technician A says that a Simpson gearset is two planetary gearsets that share a common sun gear. Technician B says that a Ravigneaux gearset has two sun gears, two sets of planet gears, and a common ring gear. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Simpson gearsets share a common sun gear and Ravigneaux gearsets share ring gears.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

5. Technician A says that that one of the primary purposes of the pressure regulator valve is to fill the torque converter with fluid. Technician B says that the pressure regulator valve directly controls throttle pressure. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. The purpose of the pressure regulator valve is to keep internal pressures at a pre-set level and to prevent excessive pressures.

6. Technician A says that the purpose of a valve body is to increase oil pressures in response to increases in engine speed. Technician B says that valve bodies are normally fitted with three different types of valves, which start, stop, or use movable parts to regulate and direct the flow of fluid throughout the transmission. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Valve bodies are used to regulate and control fluid flow for the various hydraulic circuits in the transmission.

7. Technician A says that changes in engine load cause changes in hydraulic pressure inside the transmission. Technician B says that engine load is monitored by throttle pedal movement or by engine vacuum. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. Transmission operation is affected by engine load, which can be determined by throttle opening or engine vacuum.

8. Technician A says that the rear hub of the torque converter is bolted to the flexplate.

Technician B says that the flexplate is designed to be flexible enough to allow the front of the converter to move forward or backward if it expands or contracts because of heat or pressure. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A is wrong; the shell of the converter is bolted to the flexplate.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

9. While discussing a Lepelletier system: Technician A says that two simple planetary gearsets are connected in tandem. Technician B says that these systems rely on various combinations of the planetary gears to obtain many forward gears. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician A is wrong. The Lepelletier system connects a simple planetary gearset to a Ravigneaux gearset.

10. While discussing the CVT transaxle used in Toyota hybrid vehicles: Technician A says that the transaxle contains two electric motor/ generators, a differential, and a simple planetary gearset. Technician B says that the planetary gearset adjusts the diameter of the pulleys to provide the various speed ratios. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Hybrid electric vehicles from Toyota and Ford rely on a planetary gearset to provide for a continuously variable transmission. The transaxle does not use belts and pulleys. The engine and the motor/generators are connected directly to the planetary gear unit. The planetary gearset is called the power-split device because it can transfer power between the engine, the motor/generators, drive wheels, and in nearly any combination of these.

TECH MANUAL CONCEPT ACTIVITY 41-1 Torque Converters To understand how fluid power is used in a torque converter, face two similar size fans toward each other. Turn one fan on and watch as the airflow from the first fan turns the blades of the second fan.

1.

Why does the air cause the blades of the second fan to turn?

Answer Answers will vary but include: the air moving over the blades cause them to rotate

2. Do the blades of the second fan turn as fast as those of the first fan?

Answer Answers will vary but include: yes or no

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

3. Why might the blades be turning at different speeds?

Answer Answers will vary but include: loss of air pressure against the blades 4. Are the fan blades turning in the same direction?

Answer Answers will vary but include: yes or no 5. Move the driving fan away from the driven fan. At what distance does the driven fan stop rotating?

Answer Answers will vary but include: 1 foot to several feet 6. What could be done to get the highest possible speed from the driven fan?

Answer Answers will vary but include: increase blade size, reduce frictional loses

CONCEPT ACTIVITY 41-2 Torque Converters Label the following figures as gear reduction, overdrive, direct drive, or reverse.

Walk inside ring gear

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

Walk around the sun gear

Follow the sun and ring gears

Drives the ring gear Answer Gear reduction Overdrive Direct drive Reverse

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

1.

What would be the result if none of the parts of the planetary gearset are held?

Answer No, power would be transferred.

2. How many forward speeds are available from a simple planetary gearset?

Answer Three 3. What are the three types of planetary gearsets?

Answer Simpson, Ravigneaux, Lepelletier

CONCEPT ACTIVITY 41-3 Transmission Control Examine two vehicles’ transmissions/transaxles as provided by your instructor.

Year __________ Make __________ Model __________ Transmission __________ Year __________ Make __________ Model __________ Transmission __________ 1.

Does either vehicle use a vacuum modulator?

Answer Answers will vary.

2. Describe the location of the modulator.

Answer Answers will vary.

3. Inspect the vacuum hose to the modulator. Note your findings.

Answer Answers will vary.

4. Remove the vacuum hose from the modulator and inspect for fluid leaking from the vacuum port. Note your findings.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

5. Does this modulator allow for adjustment?

Answer Answers will vary but include: yes or no 6. Why and how would the modulator need to be adjusted?

Answer Answers will vary based on vehicles used.

Answers will vary but include: if replaced, by turning a set screw 7. Does either transmission use a throttle valve (TV) cable?

Answer Answers will vary but include: yes or no 8. Describe the function of the TV Answer Answers will vary but include: to provide throttle input to transmission valve body for shifting 9. What would be some symptoms of an improperly adjusted TV cable?

Answer Answers will vary but include: shifting too soon or too late 10. Describe how to check and adjust the TV cable.

Answer Answers will vary based on vehicle.

11. Does either transmission use solenoids to control shifting?

Answer Answers will vary.

12. How many solenoids are used?

Answer Answers will vary.

13. Describe how the output of solenoids controls shifting.

Answer Answers will vary but include: solenoids open/close passages to control clutches and bands

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 41: Automatic Transmissions and Transaxles

14. Which gear range is the limp-in mode gear?

Answer Answers will vary.

15. What is the output state of the solenoids in limp-in mode?

Answer Answers will vary.

16. Are these transmissions/transaxles equipped with lockup torque converter clutches (TCCs)?

Answer Answers will vary but include: yes or no 17. What are the criteria for the PCM to command the TCC solenoid on?

Answer Answers will vary.

18. What are the criteria for the PCM to command the TCC solenoid off?

Answer Answers will vary.

19. Is the TCC commanded from off to completely on, or is it applied over several seconds?

Answer Answers will vary.

20. What problems can result from a TCC sticking in the applied position?

Answer Answers will vary but include: stalling when the vehicle comes to a stop

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 42: ELECTRONIC AUTOMATIC TRANSMISSIONS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 42-1 ......................................................................................................... 7 CONCEPT ACTIVITY 42-2 ......................................................................................................... 8 CONCEPT ACTIVITY 42-3 ......................................................................................................... 9

SHORT ANSWER 1.

Although computers receive different information from a variety of sensors, the decisions for shifting are actually based on more than the inputs. What else are they based on?

Answer Shift timing decisions are based not only on sensor input but also on a predetermined schedule and on adaptive control strategies.

2. What happens if the TCM determines that the signals from the TFT sensor are incorrect?

Answer If the TFT sensor fails or the TCM determines temperature signals are incorrect, the TCM will look at engine temperature to estimate the temperature of the ATF. 3. How can air pressure be used to check an electrical switch?

Answer Pressure switches can be tested by applying air pressure to the area of the switch that would normally be exposed to hydraulic pressure and checking the switch for leaks.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

4. Most transmissions receive information through multiplexing. How does this work?

Answer The computer may receive information from two different sources: directly from a sensor, or through a twisted-pair bus circuit, which connects all of the vehicle computer systems. This modulated bidirectional bus system allows the various computers in the vehicle to share information. Multiplexing is a system that allows voltage signals to be shared and exist on a single wire. The signal has a preset frequency that is accepted only by the intended computer or computers.

5. List five things that could cause incorrect shift times and poor shifting quality.

Answer Common problems that affect shift timing and quality: incorrect battery voltage, a blown fuse, poor connections, a defective TP sensor or VSS, defective solenoids, wires to the solenoids or sensors crossed, corrosion at an electrical terminal, or faulty installation of an accessory.

6. Most late-model transmission control systems have adaptive learning. What does this mean?

Answer The control unit is programmed to adjust its operating parameters in response to changes within the system, such as component wear. As component wear and shift overlap times increase, the control unit adjusts line pressure by controlling a variable force motor or solenoid to maintain proper shift timing calibrations.

7. What inputs are of prime importance to a computer in deciding when to shift gears?

Answer Engine speed, throttle position, temperature, engine load, and other typical enginerelated inputs are used by the computer to determine the best shift points.

8. What are the advantages of using electronic controls rather than relying on conventional hydraulic controls in a transmission?

Answer Conventional automatic transmissions waste a good amount of the torque produced by the engine through the heat generated by the moving fluid. Also because gear changes were dependent upon the movement of fluid, up and down shifts were somewhat lazy. Manufacturers could not get the transmissions to respond immediately to the needs of the vehicle without jarring the driver and the vehicle. By using electronic controls for transmission operation, the amount of wasted power can be reduced and the overall operation of the transmission can be more responsive with better reliability. Electronic controls also allow for the production of less complicated

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

transmissions, thereby reducing manufacturing and repair costs. The use of electronics eliminates many of the complex circuits and valves in a typical valve body. With this simplicity comes increased reliability, in addition to reduced costs.

9. Explain the importance of proper gearshift lever position sensor adjustment.

Answer Answers will vary but may include: Incorrect adjustment can cause the transmission to go into the wrong gear and allow the engine to start without being in park or neutral.

10. Explain how hybrid CVTs operate in conjunction with the traction motors.

Answer Answers will vary but may include: The transmission may use the electric motors to allow for any gear ratio. In some vehicles, the electric motors act as the belts and pulleys of a conventional CVT. 11. Define limp-in mode.

Answer Answers will vary but may include: Limp-in mode locks the transmission into one gear to allow the vehicle to be driven to a repair facility in the event of a major transmission fault.

MULTIPLE CHOICE 1.

Which of the following is not a voltage-generating type sensor? a. Vehicle speed sensor b. OSS c. MAP d. ISS Answer: c. The MAP sensor is a pressure switch.

2. A glitch appears in the waveform of a vehicle speed sensor. Which of the following is not a probable cause of the problem? a. A loose connector b. A damaged wire c. A poorly mounted sensor d. A damaged magnet in the sensor Answer: d. Glitches are typically caused by sudden changes in voltage, if the magnet were bad all signals would be bad.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

3. In a Toyota hybrid CVT, which of the following parts effectively controls the overall gear ratio of the transaxle? a. MG1 b. MG2 c. Reduction unit d. Transaxle damper Answer: a. The rotational speed of MG2 largely depends on the power generated by MG1. Therefore, MG1 basically controls the continuously variable transmission function of the transaxle.

4. Which of the following statements about transmission solenoids is not true? a. They can be tested with an ohmmeter. b. They can be checked with a lab scope. c. They can be air tested. d. They can be checked by listening and feeling for movement.

Answer: c. Shift solenoids are not typically air tested.

5. Which of the following would probably not be caused by a plugged filter screen at a solenoid? a. Erratic shifting b. No shift conditions c. A solenoid that will not energize d. Wrong gear starts Answer: c. This is not an electrical problem and the solenoid will energize, just not with the force it should normally open and close with. The magnetic field in the solenoid has collected metal particles that are clogging its port or check valve. These would cause erratic shifting, no shift conditions, wrong gear starts, no or limited passing (kickdown) gear, or binding shifts.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that some systems use a special modulated shift control solenoid.

Technician B says that some systems use a special modulated converter clutch control solenoid. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct The type of solenoids used can vary based on transmission design and operation.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

2. Technician A says that shift solenoids direct fluid flow to and away from the apply devices in the transmission. Technician B says that shift solenoids are used to mechanically apply a friction brake or multiple-disc clutch assembly. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Shift solenoids direct the flow of oil to apply and release various apply devices; they do not mechanically apply a band or clutch assembly.

3. Technician A says that throttle position is an important input in most electronic shift control systems. Technician B says that vehicle speed is an important input for most electronic shift control systems. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Engine speed and load information is critical for proper control of the transmission.

4. Technician A says that a faulty TP sensor can cause delayed shifts. Technician B says that delayed shifts can be caused by an open shift solenoid. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. A faulty TP sensor can cause delayed upshifts. An open shift solenoid would cause some of the shifts to be missing or the transmission to operate in limp-in mode.

5. Technician A says that some shift solenoids can be activated by providing a ground for the solenoid. Technician B says that some shift solenoids can be activated by applying hydraulic pressure to their valve. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Many computer controlled solenoids are ground side switched; hydraulic pressure does not apply a solenoid.

6. An electronically controlled transmission has erratic shifting: Technician A says that a poor PCM ground will cause this problem. Technician B says that erasing the TCM memory may cause erratic shifting. Who is correct? a. Technician A only b. Technician B only c. Both A and B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

d. Neither A nor B Answer: c. Both technicians are correct. The TCM must work properly to control shifting. A loss of adaptive memory can cause erratic shifting until the TCM relearns and adapts for wear.

7. While discussing transmission adaptive learning: Technician A says that the transmission learns to respond according to the current condition of the engine and transmission. Technician B says that the TCM learns to respond to the driver’s driving habits. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct The TCM can learn both driving habits and account for wear over the life of the transmission.

8. While discussing valve body assemblies in late-model transmissions: Technician A says that the valve body is no longer needed in some electronically controlled transmissions. Technician B says that an EPC solenoid maintains constant fluid pressure through the valve body regardless of the vehicle’s operating condition. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Solenoids do not replace the valves in a valve body, rather they control fluid pressure to the valves. The EPC solenoid changes fluid pressure to meet the needs of the transmission.

9. A transmission has delayed upshifts under all operating conditions: Technician A says that low mainline pressure can cause this. Technician B says that a faulty TFT sensor can cause this. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A faulty TFT sensor can cause the TCM to register a lower fluid temperature, which may result in delayed upshifts.

10. While diagnosing the cause of TCC shudder: Technician A checks the fluid pressure sent to the clutch. Technician B says that because the shudder occurs only after the clutch is engaged, the problem is the engine, transmission, or another component of the driveline. Who is correct? a. Technician A only b. Technician B only c. Both A and B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

d. Neither A nor B Answer: c. Both technicians are correct. Low fluid pressure can cause the TCC to shudder during application. Shudder after application is often caused by a problem other than the converter.

TECH MANUAL CONCEPT ACTIVITY 42-1 Electronic Transmissions Using a vehicle assigned to you by your instructor, determine the following.

Year __________ Make __________ Model __________ VIN __________ Engine Type and Size __________ Mileage __________ Transmission/transaxle model __________ Connect a scan tool to the DLC and begin communication with the on-board network.

1.

List the available data parameters for the automatic transmission.

Answer Answers will vary based on vehicles used.

Answers will vary but include: input speed, oil temp, output speed

2. List the inputs used for the transmission/transaxle.

Answer Answers will vary but include: engine speed, oil temp, throttle percent 3. List the outputs for the transmission/transaxle.

Answer Answers will vary but include: output shaft speed, solenoid on/off 4. List any active commands available for the transmission/transaxle.

Answer Answers will vary but include: solenoids on/off 5. How many shift solenoids does this transmission/transaxle use?

Answer

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

Answers will vary but include: 2–8 6. What is the default or limp-in gear for this transmission?

Answer

Answers will vary but include: 4th 7. Explain how the manual gear-position sensor operates on this vehicle.

Answer Answers will vary but include: an internal or external sensor connected to the shift linkage or manual valve determines shifter position 8. Does this transmission/transaxle use a torque converter clutch (TCC)?

Answer Answers will vary but include: yes or no 9. What are the parameters for the PCM/TCM to apply the TCC? Answer Answers will vary but include: steady throttle, vehicle speed above 20 mph, trans fluid temp above 80 degrees

CONCEPT ACTIVITY 42-2 Constantly Variable Transmissions Many newer vehicles have constantly variable transmissions, called CVTs. The CVT is an automatic transmission that uses a set of variable pulleys instead of fixed gearsets. Figure 42-1 shows the basic CVT arrangement. By varying the diameters of both the driving and driven pulleys, the transmission can adapt the gear ratio to the driving conditions.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 42: Electronic Automatic Transmissions

FIGURE 42–1 An example of a CVT. 1.

List three to five late-model vehicles that may have a CVT. Answer Answers will vary but include: most Nissan and Subaru cars, Honda Civics

2. What are the advantages of CVTs? Answer Engine rpm can be kept at the most efficient speed.

3. How does the operation of a vehicle with a CVT differ from that of a manual or traditional automatic transmission?

Answer A CVT uses adjustable pulleys and a belt to transfer power from the input to the output and has no set gear ranges.

CONCEPT ACTIVITY 42-3 Hybrid Drive Systems 1.

List the components that make up a nontraditional hybrid drive arrangement.

Answer planetary gear sets, electric motors, the internal combustion engine

2. Explain how the power splitter can be used to drive the wheels and also allow for recharging of the high-voltage battery pack.

Answer One motor/generator can be used to drive the wheels while the other motor/generator is producing electricity to recharge the battery.

3. Under what conditions are both the ICE and electric motors used to propel the vehicle?

Answer Under acceleration and high-speed driving 4. Under what conditions does the electric motor provide the propulsion for the vehicle?

Answer Under light to medium acceleration and low-speed cruising

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

sSolution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 43: AUTOMATIC TRANSMISSION AND TRANSAXLE SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 43-1 ......................................................................................................... 7 CONCEPT ACTIVITY 43-2 ......................................................................................................... 8 CONCEPT ACTIVITY 43-3 ......................................................................................................... 8

SHORT ANSWER 1.

What is the most probable cause of a low fluid level?

Answer A low fluid level usually indicates an external fluid leak.

2. What does milky colored ATF indicate?

Answer Transmission fluid with a milky appearance indicates that engine coolant is contaminating the transmission fluid from a faulty transmission cooler.

3. What do varnish or gum deposits on the dip-stick indicate?

Answer When there are gum or varnish deposits on the transmission dipstick, the transmission fluid needs to be changed.

4. Describe the purpose of performing transmission fluid pressure tests.

Answer Answers will vary but may include: to determine if the correct pressure is available at particular test points or components

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

5. What transmission components’ operation is verified using air pressure testing?

Answer Clutches, bands, accumulators.

6. Explain the operation of a one-way clutch.

Answer Answers will vary but may include: A one-way clutch will spin freely in one direction but will lock if turned the opposite direction.

7. List five reasons for replacing a torque converter.

Answer Reasons for replacing a torque converter: • fluid leakage from its seams or welds • loose drive studs • worn drive stud shoulders • stripped drive stud threads • hub is heavily grooved • excessive hub runout • ATF was found to be contaminated 8. Explain why oil circuit diagrams are invaluable tools for diagnosing a transmission problem.

Answer The best way to identify the exact cause of the problem is to use the results of the road test, logic, and the oil circuit charts for the transmission being worked on. Using the oil circuit charts, you can trace problems to specific valves, servos, clutches, and bands. By following the flow of the fluid on the chart, you can identify which valves and apply devices should be operating in each particular gear selector position.

Through a process of elimination, you can identify the most probable cause of the problem.

9. Explain how a plugged fluid cooler can cause a vehicle to stall when reverse is selected.

Answer Vehicles equipped with a TCC may stall when the transmission is shifted into reverse gear. This is caused by plugged transmission cooler lines or cooler. Fluid normally flows from the torque converter through the cooler. If the cooler passages are blocked, fluid is unable to exhaust from the torque converter and the converter clutch

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

piston remains engaged. When the clutch is engaged, there is no vortex flow in the converter and therefore little torque multiplication is taking place in the converter.

10. What is checked during a stall test?

Answer The stall test checks the holding capacity of the converter’s stator overrunning clutch assembly, as well as the clutches and bands in the transmission.

11. If a transmission does not have a dipstick, how do you check the level of the fluid?

Answer When servicing a valve body, ensure that each valve moves freely in its bore. If it does not move freely, clean the valve and the bore and retest. If the valve cannot be cleaned enough to move freely in its bore, it is usually replaced.

12. What should you do if a valve does not move freely in its bore in the valve body?

Answer To check the fluid level, the transmission must be warm and the vehicle must be on a level surface or raised on a lift. It is important that all four wheels are raised, as just lifting the front will put the vehicle on a slant and you will be unable to get an accurate reading. Find the fill plug and remove it. A small of fluid should leak out of the vent/fill opening if the fluid is at the correct level.

MULTIPLE CHOICE 1.

Which of the following is the most likely cause for a shudder during the engagement of a lock-up torque converter? a. A bad converter b. Worn or damaged CV or U-joints c. A worn front planetary gearset d. Loose flexplate Answer: a. When a shudder occurs during engagement of the torque converter clutch, the problem is typically in the converter.

2. When should the ATF level be checked on most vehicles? a. When the transmission is cool b. When the engine is at operating temperature and the engine is off c. When the transmission is at operating temperature and the engine is on d. It does not matter Answer: c. Check the transmission fluid level at operating temperature with the engine running.

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

3. Pressure readings reveal possible problems in which of the following? a. Oil pump b. Governor c. Apply circuits d. All of the above Answer: d. All of the above 4. Which of the following is a probable cause for a converter’s stall speed being below specifications? a. Restricted exhaust b. Slipping transmission clutches c. Slipping transmission bands d. Worn planetary gearset Answer: a. If the stall speed is below the specifications, a restricted exhaust or slipping stator clutch is indicated. If the stall speed is above specifications, the bands or clutches in the transmission may be slipping and not holding properly. Worn gears would have no effect on stall speed.

5. When rebuilding an automatic transmission, which of the following is not true? a. All pumps, valve bodies, and cases should be checked for warpage and should be flat filed to take off any high spots or burrs prior to reassembly. b. Only use lint-free rags to wipe parts off. c. Lubricate all thrust washers, bearings, and bushings before installing them. d. Soak all friction materials in clean engine oil prior to installing them.

Answer: d. Soak all friction materials in clean ATF prior to installing them.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a prerequisite to accurate road-testing analysis is knowing what planetary controls are applied in a particular gear range. Technician B says that all slipping conditions can be traced to a leaking hydraulic circuit. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Effective diagnosis and testing depends on understanding which planetary controls are applied in each particular gear range. Not all slipping conditions are due to a leaking hydraulic circuit; other factors such as worn, glazed, or incorrect friction elements can also cause slippage.

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

2. While discussing proper band adjustment procedures: Technician A says that on some vehicles the bands can be adjusted externally with a torque wrench. Technician B says that a calibrated inch-pound torque wrench is normally used to tighten the band adjusting bolt to a specified torque. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Some transmission provide an external adjustment and all adjustments should be performed according to the manufacturers service procedures.

3. Technician A says that if the shift for all forward gears is delayed, a slipping forward clutch is normally indicated. Technician B says that a bad forward clutch is indicated when there is a slip when the transmission shifts into any forward gear. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. When there is slippage in any (all) forward gears, a faulty forward clutch is suspected. A delayed upshift would not be related to the forward clutch, but would more likely be due to the governor or the throttle valve.

4. Technician A says that the only positive way to identify the exact design of the transmission is by the shape of its oil pan. Technician B says that identification numbers only identify the manufacturer and assembly date of the transmission. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Using the shape of the transmission pan to identify the type of transmission is only one method; additional information such as make, model, and assembly date are available using the transmission identification number.

5. Technician A says that delayed shifting can be caused by worn planetary gearset members. Technician B says that delayed shifts or slip-page may be caused by leaking hydraulic circuits or sticking spool valves in the valve body. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Delayed shifting may be the result of sticking spool valves or slow application of clutches due to leaking hydraulic circuits. Worn planetary gearset members would more likely result in noise.

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

6. While checking the condition of a car’s ATF: Technician A says that if the fluid has a dark brownish or blackish color and/or a burned odor, the fluid has been overheated.

Technician B says that if the fluid has a milky color, this indicates that engine coolant has been leaking into the transmission’s cooler. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Overheated fluid is often dark and has a burnt smell. Coolant mixed with the fluid can cause a milky color.

7. While discussing the results of an oil pressure test: Technician A says that when the fluid pressures are high, internal leaks, a clogged filter, low oil pump output, or a faulty pressure regulator valve are indicated. Technician B says that if the fluid pressure increased at the wrong time, an internal leak at the servo or clutch seal is indicated.

Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. The problems described would be indicated by lower, not higher, pressure.

8. While discussing a pressure test: Technician A says that a pressure drop of more than 15 psi during a shift indicates a possible leak. Technician B says that any pressure drop between shifts indicates a problem. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A drop in pressure can indicate a problem in the hydraulic circuit being tested.

9. While checking the engine and transmission mounts on a FWD car: Technician A says that any engine movement may change the effective length of the shift and throttle cables and there-fore may affect the engagement of the gears. Technician B says that delayed or missed shifts are caused by hydraulic problems, not linkage or control problems. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Common causes for delayed or missed shifts are linkage and control (sensor) problems.

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

10. While discussing the cause of aerated fluid in a transmission: Technician A says that this can be caused by too much ATF in the transmission. Technician B says that this can be caused by too little ATF in the transmission. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both are correct. When the fluid level is low, air can be drawn into the oil pump’s inlet circuit and mix with the fluid. When there is too much fluid, air can be forced into the fluid as the planetary gears rotate in high fluid levels.

TECH MANUAL CONCEPT ACTIVITY 43-1 Transmission/Transaxle Identification To accurately diagnose and service a transmission/transaxle, you must know exactly what model transmission/transaxle you are working on.

1.

Locate the transmission/transaxle identification tag and record the information. The tag is usually located on the bell housing or other visible area (Figure 43-1).

FIGURE 43–1 An example of a transmission ID tag.

Answer Answers will vary.

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sSolution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 43: Automatic Transmission and Transaxle Service

CONCEPT ACTIVITY 43-2 Transmission Fluids Match the following common transmission fluids with the manufacturer.

Dexron

Honda

Mercon

General Motors

ATF +4

Toyota

ATF -Z1

Chrysler

T-III & T-IV

Ford

Always refer to the manufacturer’s service information regarding the proper automatic transmission/transaxle fluids.

Answer Dextron Mercon ATF +4 ATF -DW1 T-III & T-IV

= General Motors = Ford = Chrysler = Honda = Toyota

CONCEPT ACTIVITY 43-3 Torque Converter Testing Using a vehicle assigned to you by your instructor, determine the proper procedures to perform a torque converter stall test. Always refer to the service information to determine whether the manufacturer recommends stall testing for a particular vehicle.

1.

Manufacturer’s warnings and precautions: Answer Answers will vary but include: do not perform a stall test; ensure parking brake is set; chock drive wheels; and do not perform for longer than 10 seconds.

2. Vehicle preparation: Answer Answers will vary but include: warm transmission fluid to specific temperature, set parking brake, chock drive wheels, check and set transmission fluid level as needed

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 44: Four- and All-Wheel Drive

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 44: FOUR- AND ALL-WHEEL DRIVE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4

SHORT ANSWER 1.

Name the three main driveline components that are added to a RWD vehicle to make it a 4WD vehicle.

Answer A four-wheel drive has (1) a transfer case, (2) a front drive shaft, and (3) a front drive axle.

2. Describe the purpose of a viscous clutch.

Answer A viscous clutch transfers power to drive the axle with low traction, replacing the center differential in an all-wheel-drive application.

3. What is the purpose of the interaxle differential?

Answer An interaxle differential dissipates driveline windup, allowing the front and rear axles to operate at different speeds.

4. Briefly explain how a Haldex clutch works.

Answer The Haldex unit is much like a hydraulic pump in which the housing and a piston are connected to one shaft and a piston actuator connected to the other. When a front wheel slips, the input shaft to the Haldex unit spins faster than its output shaft. This causes the pump to immediately generate oil flow. The oil flow and pressure engages the multi-disc clutch to send power to the rear wheels. This happens extremely quickly because an electric pump and accumulator keep the circuit primed. The oil

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 44: Four- and All-Wheel Drive

from the pump flows to the clutch’s piston to compress the clutch pack. The oil returns to the reservoir through a controllable valve, which adjusts the oil pressure and the force on the clutch pack. An electronic control module controls the valve and also determines when to decouple the axles to prevent the rear brakes from braking the front axle. In high slip conditions, a high pressure is delivered to the clutch pack: in tight curves or at high speeds, a much lower pressure is provided. When there is no difference in speed between the front and rear axles, the pump does not supply pressure to the clutch pack.

5. What is the primary purpose of a transfer case?

Answer The purpose of a transfer case is to transfer torque, from the output of the transmission to the vehicle's front and rear axles.

6. What are the primary differences between a full-time and a part-time 4WD system?

Answer Part-time 4WD systems are manually controlled systems. They operate as a 2WD until the driver does something to activate or engage the other axle. Then torque is divided between the two axles and all four wheels can be driven. These systems have a fixed torque split between the front and rear. They also do not corner well at speed when 4WD is engaged because tire slip is the only way these systems accommodate for the differences in travel distance between the front and rear tires as the vehicle goes through a turn. With full-time 4WD, the system is permanently powering all four wheels. In these systems the driver cannot select 2WD. 7. How does a viscous clutch assembly work? Why is it used in AWD systems?

Answer When used in an all-wheel-drive application, a viscous clutch takes the place of a center differential in the transfer case. Each axle is allowed to operate at different speeds during conditions such as cornering, but when one axle has less traction, the difference in rotating speeds causes the clutch to lock up and transfer more torque to the axle with better traction. This is useful in all-wheel-drive applications because driveline windup is eliminated while traction and handling are improved.

8. What is the advantage of using limited-slip differentials?

Answer Answers will vary but may include: It allows traction to be applied to a drive wheel while the other drive wheel is slipping.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 44: Four- and All-Wheel Drive

9. Explain the importance of having the proper tire sizes on 4WD and AWD vehicles.

Answer Answers will vary but may include: Different size tires will cause different tire speeds, which can damage 4WD and AWD systems 10. Explain two methods of engaging the 4WD system.

Answer Mechanically though shift linkage and hub locks, by a vacuum control, and by an electric motor.

MULTIPLE CHOICE 1.

What results from having different axle ratios on the front and rear of a 4WD vehicle when it is operating in 4WD? a. Poor handling on dry surfaces b. Driveline windup c. Mechanical damage to the driveline d. All of the above Answer: b. This condition would result in severe driveline windup.

2. The transfer clutch in the all-wheel drive automatic transaxle takes the place of the ___. a. transmission b. reduction gears c. torque converter d. interaxle differential Answer: d. The transfer clutch functions as an interaxle differential.

3. In a viscous clutch, when the silicone fluid is heated, it ___. a. becomes a very thin fluid b. boils to a vapor c. thickens to a solid mass d. stiffens Answer: d. The fluid in a viscous clutch stiffens as it becomes heated.

4. When servicing transfer cases, all of the following are correct, except ___. a. it must be supported on a transmission jack or safety stands b. the chain drive and a planetary gearset must be adjusted to specifications c. visual inspections for leaks and damage are necessary d. follow the manufacturer’s recommendations for lubricants Answer: b. Not all transfer cases have either of these components.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 44: Four- and All-Wheel Drive

5. Which of the following is least likely to cause binding when turning on the front of a 4WD vehicle? a. Unmatched tire sizes b. Unequal tire wear c. Low differential fluid level d. Unequal tire pressures Answer: c. Low fluid level is unlikely to cause binding while turning compared to the concerns.

6. Which of the following would not cause noise while driving in 2WD under a heavy throttle? a. Faulty ignition switch b. Worn transfer case clutch c. Inoperative locking hubs d. Bad front half shaft Answer: b. A faulty clutch will cause improper switching between 2WD and 4WD. 7. Which of the following could cause the 4WD indicators not to operate correctly? a. A faulty control module (PCM) b. Inoperative locking hubs c. Worn transfer case clutch d. Damaged transfer case shift lever Answer: a. The other choices would cause the unit not to shift properly.

8. Technician A says all transfer cases are 1:1 ratio cases. Technician B says some transfer cases allow for gear reduction. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B Answer: b. Tech B. Transfer cases typically have a 1:1 ratio and a gear reduction

ratio for increased torque.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that viscous couplings are electronically controlled. Technician B says that Haldex clutches are electronically controlled. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Neither of these components is electronically controlled.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 44: Four- and All-Wheel Drive

2. Technician A says that some AWD systems have a center differential. Technician B says that some AWD vehicles have a viscous clutch. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Manufacturers use several methods of providing AWD, including center differentials and differentials with viscous clutches.

3. While discussing AWD systems: Technician A says that some systems are electronically controlled and use an electromagnetic clutch to engage and disengage the drive axles.

Technician B says that some cars do not use a transfer case, but they are equipped with a third differential unit. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Manufacturers use several methods of providing AWD, including center differentials and differentials with electronic clutches.

4. Technician A says that the 4WD mode of part-time 4WD systems is designed to be used only when driving off the road or on slippery surfaces. Technician B says that AWD systems are intended for off-the-road use only. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. AWD systems are not designed for off-the-road use or heavy pulling.

5. While diagnosing the cause of noise from a transfer case: Technician A says that a probable cause is incorrect tire size. Technician B says that the most probable cause is a faulty bearing or gear. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Unequal tire sizes and mechanical problems can cause noise from the transfer case.

6. Technician A says that a seized shift linkage may cause the transfer case to operate only in 4WD. Technician B says that a worn and loose linkage may cause a transfer case to operate only in 2WD. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Worn or stuck linkage components can cause the transfer case to be stuck in one mode of operation.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 44: Four- and All-Wheel Drive

7. While diagnosing the cause of the transfer case jumping out of gear: Technician A says that the most probable cause is worn or broken synchronizers. Technician B says that a possible cause is an improperly adjusted shift linkage. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. The transfer case does not have synchronizers.

8. While servicing an AWD vehicle: Technician A checks the service information to identify the correct lubricant for the center differential. Technician B says that the same lubricant is used for the viscous coupling, transfer case, and differentials on most vehicles. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Each of these components may require a different lubricant. Viscous couplings require a special lubricant.

9. While discussing the various speed gear positions of a transfer case: Technician A says that when the transfer case is in low, the overall gear ratio is numerically increased.

Technician B says that when the transfer case is in the high position, the vehicle operates in an overdrive mode due to the decrease in torque multiplication. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. There is no overdrive from a transfer case.

10. While discussing automatic AWD systems: Technician A says that the systems operate in 2WD nearly all of the time. Technician B says that on many systems, when the PCM detects wheel slippage, power is sent to the other drive axle. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Most systems operate in 2WD mode unless additional traction is needed. Electronic systems can direct power to the each drive axle as needed.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 45: TIRES AND WHEELS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 45-1 ......................................................................................................... 7 CONCEPT ACTIVITY 45-2 ......................................................................................................... 8 CONCEPT ACTIVITY 45-3 ......................................................................................................... 9 CONCEPT ACTIVITY 45-4........................................................................................................ 10 CONCEPT ACTIVITY 45-5 ........................................................................................................ 11 CONCEPT ACTIVITY 45-6........................................................................................................ 12 CONCEPT ACTIVITY 45-7 ........................................................................................................ 13

SHORT ANSWER 1.

What are the primary purposes of tires?

Answer Answers will vary but may include: To provide traction and absorb road shock.

2. What is the difference between a wheel bearing and an axle bearing?

Answer Answers will vary but may include: Wheel bearings are on non-driving wheels and axle bearings are on driving wheels.

3. How can improper wheel torque affect the hub and bearing assemblies?

Answer Answers will vary but may include: Improper torque can damage the wheel and the hub, causing vibration.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

4. List five things that could cause premature bearing failure.

Answer The causes of premature bearing failure are: • Lack of lubrication • Improper type of lubrication • Incorrect endplay adjustment (where applicable) • Misalignment of related components, such as shafts or housings • Excessive bearing load • Improper installation or service procedures • Excessive heat • Dirt or contamination 5. Define lateral and radial runout and explain how to check wheel/tire runout.

Answer Lateral runout is movement from side to side. Radial runout is when a round object, such as a wheel or tire is out of round. Both can be checked using a dial indicator.

6. Why is tire rotation recommended by most manufacturers?

Answer Driving habits determine tire life to a large extent. Severe brake applications, highspeed driving, turning at high speeds, rapid acceleration and deceleration, and striking curbs are just a few driving habits that shorten tire life. To equalize tire wear, most car and tire manufacturers recommend that the tires be rotated at specified intervals to obtain maximum tire life.

7. Define dynamic and static wheel balance.

Answer Dynamic balance is described as an equal distribution of weight on each side of the tire’s centerline. Static balance is an equal distribution of weight around the circumference of the tire.

8. Describe the proper procedure to seal a puncture in a tire.

Answer A tire may be repaired using a plug that is slightly larger than the size of the puncture.

Some plugs are inserted from inside the tire and pulled through with an installation tool, while others may be installed using an installation tool without removing the tire from the wheel. The plug is cemented in place and the excess is trimmed off, with care being taken not to pull on the plug while trimming it.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

9. Explain why a TPMS relearn should be performed even after a basic tire service.

Answer A TPMS relearn should be performed to make sure the TPMS is correctly calibrated for the set tire pressure and tire location.

MULTIPLE CHOICE 1.

A tire that wobbles from side-to-side is said to have ___. a. radial runout b. lateral runout c. static imbalance d. none of the above Answer: b. Lateral runout is described as a side-to-side wobble.

2. A front tire has excessive wear on both edges of the tire tread. The most likely cause of this problem is ___. a. overinflation b. underinflation c. improper static balance d. improper dynamic balance Answer: b. Underinflation places a greater load on the outer edges of the tire.

3. All of the following statements are correct except? a. Belts are reinforcing materials that encircle the tire under the tread. b. The carcass of a tire is made up of plies, layers of cloth, and rubber. c. Most tread patterns are designed to work well on both wet and dry roads. d. The bead is the decorative pattern at the outer edge of the tread.

Answer: d. The bead is the portion of the tire that seals against the rim.

4. All of the following statements are correct except? a. Tire inflation pressure directly affects traction. b. The recommended tire pressure for front and rear tires may be different. c. The recommended tire pressures are often lower than maximum pressures. d. The recommended tire pressure is molded into the sidewall of the tire.

Answer: d. The tire pressure molded into the sidewall of the tire is the maximum, not the recommended, pressure.

5. Which of the following statements about side-wall markings is correct? a. The load index is given as a letter. b. The traction and temperature ratings are based on the speed rating of the tire. c. The tire’s recommended inflation pressure and load are indicated. d. The DOT code indicates when and where the tire was made.

Answer: d. The DOT code indicates when and where the tire was made

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

6. All of these statements about improper wheel balance are true except? a. Dynamic imbalance may cause wheel shimmy. b. Dynamic imbalance may cause steering pull in either direction. c. Static imbalance causes wheel tramp. d. Static imbalance causes rapid wear on suspension components.

Answer: b. Neither static nor dynamic imbalance would cause a vehicle to pull.

7. Recommended tire inflation pressure can be found on the ___. a. engine block b. tire placard c. VIN tag d. certification label Answer: b. The tire placard contains information about the tire.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that the front wheel bearings on a typical FWD car are pressed in and out of the steering knuckle assembly. Technician B says that the front wheel bearings on a typical FWD may be bolted into the steering knuckle. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.Wheel bearings are either press fit into the knuckle or bolted into place.

2. Technician A says that dynamic wheel imbalance causes wheel tramp. Technician B says that static wheel imbalance causes wheel tramp. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Static wheel unbalance causes wheel tramp 3. Technician A says that front bearing assembly locknuts for RWD vehicles are typically heavily torqued to maintain the bearing adjustment. Technician B says that the axle nuts for a FWD wheel bearing assembly is often staked in place to maintain its specified torque. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

Answer: b. The front bearing lock nuts are only tightened enough to achieve the desired endplay. Some axle nuts on FWD applications are staked in place after being torqued.

4. Technician A says that replacement wheel rims should be the same as the original equipment wheels in load capacity, offset, width, diameter, and mounting configuration. Technician B says that if wheels are installed that have a different stock width or diameter, make sure to use a tire that has the same overall width as the original tires. Otherwise the vehicle’s wheel-speed sensors, speedometer, antilock brake system, and many other systems will be affected. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Overall tire diameter will affect the operation of the sensors, not rim width.

5. Technician A says that underinflation can increase the rolling resistance of a tire.

Technician B says that underinflation can cause hard steering and a 10 percent decrease in fuel economy. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Underinflation of the tire increases rolling resistance and can increase steering effort and fuel use.

6. While choosing the correct tire for a vehicle: Technician A says that replacing a tire with a temperature resistance rating of B with one rated with an A will increase tire life and improve ride quality. Technician B says that the traction rating indicates how well a tire will perform in the snow. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither of the technicians are correct. The traction rating is based on a wet stopping surface, not a snow covered surface and the temperature rating of a tire does not affect its service life or handling qualities.

7. Technician A says that on most vehicles, the wheel/tire assembly is considered sprung weight. Technician B says that low unsprung weight makes the vehicle handle better on irregular surfaces. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

Answer: b. Sprung weight represents the weight of the vehicle that is supported by the suspension. The suspension and wheels are unsprung weight. Low unsprung weight makes the vehicle handle better, primarily on irregular surfaces. It also gives a better ride.

8. While discussing run-flat tires: Technician A says that some are self-sealing tires and are designed to quickly and permanently seal sidewall area punctures. Technician B says that most of these tires have reinforced side-walls that are able to support the vehicle at any speed without air in the tire. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Self-sealing tires are designed to quickly and permanently seal most treadarea punctures. When a self-supporting tire loses all of its air pressure, it is able to temporarily carry the weight of the vehicle and allow the vehicle to be driven for 50 miles (80 km) at speeds up to 55 mph (89 km/h), after it has lost air pressure. These tires have reinforced sidewalls and special beads.

9. Technician A says that the aspect ratio of a tire represents the relationship between the tire’s cross-sectional height to its cross-sectional width. Technician B says that low aspect ratios provide a softer ride because they will deflect more over irregular surfaces and under heavy loads. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. A tire's aspect ratio is the relationship of its cross-sectional height (from tread to bead) to its cross-sectional width (from sidewall to sidewall). Higher aspect ratios provide a softer ride because they will deflect more over irregular surfaces and under heavy loads. Shorter sidewall heights demand stiffer sidewalls. Therefore, tires with a low aspect ratio have a harsher ride.

10. While discussing the effects of loose wheel bearings: Technician A says that vibration may occur while driving. Technician B says that the bearing may make noise. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Worn wheel bearings often make noise and may feel loose.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

TECH MANUAL CONCEPT ACTIVITY 45-1 Tire Construction

1.

Identify the components of the tire shown in the following figure. a. __________ Answer Bead core b. __________ Answer Bead liner c. __________ Answer Tread base d. __________ Answer Cap tread e. __________ Answer Carcass plies

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

f.

__________

Answer Bead reinforcement g.

__________

Answer Steel belt/cord plies 2. Examine several tires in your lab and note their traction ratings. Compare the traction ratings and the tire construction from the sidewall information.

Tire 1: __________ Traction

Construction Materials __________

Tire 2: __________ Traction

Construction Materials __________

Tire 3: __________ Traction

Construction Materials __________

Answer Answers will vary.

3. How do you think tire construction affects its traction rating?

Answer Answers will vary.

CONCEPT ACTIVITY 45-2 Tires and Air Pressure 1.

How can the tires, with only 30 psi of air pressure, support the weight of a 4,000pound vehicle?

Answer Answers will vary but may include tires can support vehicle weight since the air pressure is acting over the entire volume of the tire which spreads the load out.

2. How does tire air pressure affect vehicle ride quality?

Answer Too high or too low will cause a harsh ride.

3. How does the friction caused by the tire’s contact with the road affect the tire’s air pressure?

Answer As temperature increases so does the pressure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

4. Why does tire air pressure decrease in cold weather?

Answer The air within contracts and reduces the pressure.

5. How does tire pressure affect tread wear?

Answer Overinflation will balloon out the center of the tread and cause wear, and underinflation will allow the center to bow in and cause wear on the outer edges.

Some owners have their tires inflated with nitrogen instead of compressed air.

6. How can you tell if a tire is inflated with nitrogen?

Answer It will have a green valve stem cap.

7. What are some of the benefits of nitrogen inflation?

Answer Less expansion/contraction and reduced air loss

CONCEPT ACTIVITY 45-3 Tire Pull Tires have to be able to roll in a straight path perpendicular to the road surface. If a tire is slightly misshaped or if the belts within the tire are not parallel, tire pull can occur. To illustrate this problem, take a plastic or Styrofoam cup and place it on its side on a workbench. Attempt to roll the cup in a straight line.

1.

Describe how the cup rolls.

Answer Answers will vary but include: in a circle around the small diameter

2. Why does the cup roll as it does?

Answer Answers will vary but include: the small diameter rolls faster than the larger diameter

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

3. If a vehicle has a pull to one side, and tire pressure and alignment are correct, how would you diagnose the concern?

Answer Answers will vary but include: switch the two front tires from side to side or front to rear and retest

CONCEPT ACTIVITY 45-4 Balance Obtain a plastic lid from a coffee can and, in the exact center, drill a hole just large enough for a pencil or similar straight rod to pass through. The hole needs to allow the lid to rotate easily on the pencil.

1.

Spin the lid and note any wobble from side to side.

Answer Answers will vary.

Tape a small weight, such as a quarter, to the lid near the outside edge.

2. Does the lid rotate down on its own?

Answer Answers will vary.

3. Why does the lid rotate down with the weight?

Answer Answers will vary based on supplies used.

Answers will vary but include: gravity pulls the weight down 4. Spin the lid and note how well it rotates.

Answer Answers will vary.

5. What effect will the added weight have on the rotation of the lid?

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

6. If this were a wheel and tire assembly, how would this heavy spot affect the rotation of the assembly?

Answer Answers will vary but include: it can cause the wheel/tire to tramp or shimmy, causing vibration 7. What symptom(s) could this imbalance cause?

Answer Answers will vary but include: steering wheel or vehicle vibration 8. How could this problem be corrected?

Answer Answers will vary but include: rebalancing the wheel/tire

CONCEPT ACTIVITY 45-5 Wheel Construction

1.

Identify the sections of the wheel in the following figure.

Hub

__________

Width

Bead

__________

Valve stem

Drop center __________

__________ __________

TPMS sensor __________

Drop center __________

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

Answer

mounting holes, wheel, centerbore, center section, drop center section, rim, bead area.

2. Describe wheel offset.

Answer The distance from the center of the wheel to the mounting hub location 3. What other components or systems can be affected by changing wheel offset?

Answer Scrub radius, steering effort, wheel bearing loading, brake cooling Wheels have specific bolt patterns, the spacing between the holes for the wheel fasteners.

Even though a set of wheels may appear similar, their hub openings and lug patterns may be different. Installing an incorrect wheel assembly could lead to serious injury or death.

Locate a selection of wheels as supplied by your instructor.

4. Draw and label the measurement of the lug pattern and hub opening diameter for three different rims in the space below.

Wheel 1 __________

Wheel 2 __________

Wheel 3 __________

Answer Answers will vary.

CONCEPT ACTIVITY 45-6 Wheel and Tire Inspection Inspect several wheels and tires and note the following: 1.

Visible dents or bending of the wheel Answer Answers will vary based on inspection Answers will vary.

2. Cuts in the tire tread or sidewall Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

3. Damage to the valve stem Answer Answers will vary.

4. Condition of hub and wheel fastener holes Answer Answers will vary.

5. Tread wear pattern Answer Answers will vary 6. Bulges or swelling of the tire Wheels and/or tires that exhibit signs of serious damage or wear should be replaced.

Answer Answers will vary.

CONCEPT ACTIVITY 45-7 Wheel Bearing Inspection Obtain a sealed wheel bearing and a serviceable tapered roller bearing from your instructor.

1.

Rotate each bearing by hand and compare how easily each moves.

Answer Answers will vary.

2. Examine each bearing and describe how each is able to handle the loads placed upon it.

Answer Answers will vary.

3. Inspect each bearing for wear and signs of damage.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 45: Tires and Wheels

4. What components or actions can cause premature bearing wear or failure?

Answer Answers will vary based on inspection Answers will vary but include: incorrect wheel offset, driving habits, impacts to the wheel/tire, incorrect installation or service

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 46: SUSPENSION SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 46-1 ......................................................................................................... 7 CONCEPT ACTIVITY 46-2......................................................................................................... 9 CONCEPT ACTIVITY 46-3........................................................................................................ 10 CONCEPT ACTIVITY 46-4 ....................................................................................................... 11 CONCEPT ACTIVITY 46-5........................................................................................................ 13

SHORT ANSWER 1.

Describe how a stabilizer bar works.

Answer A stabilizer bar is sometimes referred to as a sway bar. It stabilizes the suspension system by transferring the movement of one wheel over to the opposite wheel to create a more level ride. If both wheels go into a jounce, the sway bar simply rotates in its bushings. When only one wheel goes into jounce, the bar twists like a torsion bar to lift the frame and the opposite side of the suspension. This reduces body roll.

2. Explain the difference between sprung and unsprung weight.

Answer Sprung weight consists of all of the weight of the vehicle supported by the suspension system. Unsprung weight includes undercar components such as the axles, control arms, and steering knuckles that are not supported by the springs. A low ratio of unsprung weight is desirable for better ride quality.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

3. What are the two reasons for using an air spring?

Answer An air spring operates on the principle that as a bag filled with compressed air is compressed, pressure in the bag increases. Increasingly more force is required to accomplish additional compression of the bag. In this way, an air spring functions as a variable rate spring and replaces conventional springs.

4. Explain the action of the conventional shock absorber on both compression (jounce) and rebound strokes.

Answer A conventional shock absorber dampens suspension movement by operating on the principle of fluid displacement through an orifice. It is a velocity-sensitive hydraulic dampening device. The faster it moves, the more resistance it has to movement.

Kinetic energy (energy of motion) is converted to heat and dissipated to the atmosphere. As the rod of the shock absorber is forced inward during the compression cycle, it helps control the vehicle’s sprung weight. During the extension cycle, when the rod is pulled outward, it controls the unsprung weight. A typical shock absorber is designed to have a higher ratio of resistance during its extension cycle. An air spring allows for an adjustable ride quality and adjustable ride height.

5. Describe the action of the independent front wheel suspension system.

Answer An independent suspension system allows each wheel to move independently in response to inputs from the road surface, braking torque, and body motion without affecting the other wheels.

6. Describe the common complaints caused by faulty shock absorbers.

Answer When a vehicle wheel strikes a bump, the wheel and suspension move upward in relation to the chassis. This jounce action causes the spring to deflect or compress.

Under this condition, the spring stores energy and springs back downward with all the energy absorbed when it deflected upward. If this spring action were not controlled, the wheel would strike the road with a strong downward force, and the wheel jounce would occur again. Therefore, some device must be installed to control the spring action, or the wheel would bounce up and down many times after it hit a bump, causing passenger discomfort, directional instability, and suspension component wear.

Bad shock absorbers will cause excessive bounce after bumps and noise when going over bumps.

7. Explain the purpose of the stabilizer bar/bushings.

Answer Answers will vary but may include: The stabilizer bar reduces body roll during cornering.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

8. What is the most likely cause for lower-than-specified ride height?

Answer Weak or broken springs 9. What suspension components are typically eliminated by a MacPherson strut suspension?

Answer Upper control arms and upper ball joints 10. What is meant by a “wet” strut?

Answer Answers will vary but may include: a replaceable shock inside of a strut

MULTIPLE CHOICE 1.

What occurs when a wheel hits a dip or hole and moves downward? a. Jounce b. Free length c. Deflection d. Rebound Answer: d. When the wheel moves downward from the frame, it is called rebound.

2. Which of the following is part of the sprung weight of a vehicle? a. Steering linkage b. Tires c. Engine d. All of the above Answer: c. The steering linkage and the tires are part of the unsprung weight; the engine is part of the sprung weight of the vehicle.

3. What occurs when a wheel hits a dip or hole and moves upward? a. Jounce b. Free length c. Deflection d. Rebound Answer: a. When the wheel hits a bump and moves upward, it is called jounce.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

4. The modified MacPherson rear strut suspension is common in ___. a. FWD vehicles b. RWD vehicles c. pickup trucks d. station wagons Answer: a. The modified MacPherson strut rear suspension is very common in frontwheel drive vehicles.

5. What is used to control the movement of a vehicle as it goes around corners? a. Struts b. Shock absorbers c. Stabilizer bar d. Control arms Answer: c. The stabilizer bar helps control the motion of the vehicle when cornering.

6. The coil springs of the vehicle ___. a. support the weight of the vehicle b. provide axle location c. stabilize the up-and-down movement d. all of the above Answer: a. The coil springs of the vehicle support its weight.

7. SLA systems in common use today are used in the ___. a. coil spring suspension b. torsion bar suspension c. strut and control arm suspension d. all of the above Answer: d. SLA suspension systems are still used in several front suspension designs.

8. A multilink front suspension contains which of the following? a. Strut b. Control arms c. Ball joints d. All of the above Answer: d. All of these components are present in a multilink suspension.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that the use of firmer, urethane bushings in the suspension improves the vehicle’s road-holding ability and handling. Technician B says that firmer bushings help eliminate torque steer in some FWD vehicles. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

Answer: c. Both technicians are correct. Firmer bushings can improve ride quality and handling by limiting excess movement.

2. Technician A says that load-carrying ball joints should always have some play in them.

Technician B says that follower ball joints should never have some play in them. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Follower ball joints should be replaced when any perceptible play is found.

Load carrying ball joints will have zero play until they begin to wear and are not replaced until they exceed the wear limits.

3. Technician A says that a weak suspension spring can cause a loss of traction during acceleration. Technician B says that a weak suspension spring can cause poor braking power. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A weak spring can reduce the force on a tire against the road, causing reduced traction.

4. Technician A says that leaf spring-type rear suspensions are subject to axle tramp.

Technician B says that an antisway bar is designed to limit wheel tramp. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. It is the shock absorbers that are designed to limit wheel tramp among other things. Leaf-spring-type rear axle suspensions are subject to axle tramp.

5. Technician A says that shock absorbers should be inspected for loose mounting bolts and worn mounting bushings. Technician B says that shock absorbers and struts should be inspected for oil leakage. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A weak spring can reduce the force on a tire against the road, causing reduced traction.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

6. While discussing types of coil springs: Technician A says that linear-rate coil springs have equal spacing between the coils. Technician B says that a variable-rate spring may have a cylindrical shape with unequally spaced coils. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

7. When the front wheels are turned on a vehicle equipped with front struts, the left front coil spring provides a chattering action and noise: Technician A says that the strut has internal defects and strut replacement is necessary. Technician B says that the upper strut bearing and mount are defective. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Chattering during turns is caused by a defective strut mount and not the strut.

8. Technician A says that the suspension switch must be turned off before raising any corner of a car with an electronic air suspension. Technician B says that the ignition switch must not be turned on while any corner of a car with electronic air suspension is raised. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. The system should be turned off anytime this type of vehicle is raised in a hoist, lift, or jack.

9. While conducting a bounce test: Technician A says that the bumper should be pushed two or three times downward with considerable weight applied on each corner of the vehicle. Technician B says that one free upward bounce should stop the vertical chassis movement if the shock absorber or strut provides proper spring control. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Basic shock operation should provide resistance to excessive bounce.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

10. Technician A says that rattling on road irregularities can be caused by worn shock absorber bushings or grommets. Technician B says that dry or worn control arm bushings may cause a squeaking noise on irregular road surfaces. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

TECH MANUAL CONCEPT ACTIVITY 46-1 Oscillations Clamp a wooden or plastic ruler to a workbench so that approximately 10 inches (25.4 cm) of the ruler is extended off the bench top. Push the end of the ruler down about 1 inch (2.54 cm) and let go.

1.

Try to count the number of ruler oscillations before the movement stops. If the oscillations are too quick, measure the amount of time it takes to stop moving instead.

Oscillations __________ Length of time __________ Answer Answers will vary based on ruler.

Answers will vary but include: 10 over 5 seconds

2. Now move the ruler so that only five inches (12.7 cm) is extended from the table, and retest.

Oscillations __________ Length of time __________ Compare the results of the two experiments. __________ Answer Answers will vary but include: 5 over 5 seconds 3. Which test produced more oscillations?

Answer Answers will vary.

4. Describe why you think this occurred.

Answer Answers will vary but include: shorter distance to clamp reduced vibrations

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

5. Why does changing the length of the ruler affect its oscillation rate?

Answer Answers will vary but include: by increasing or decreasing the amount of ruler able to vibrate 6. Move the ruler back so that about 10 inches (25.4 cm) is extended from the table.

Place a weight of known quantity on the end of the ruler and note the amount of deflection.

Weight __________ Deflection __________ Answer Answers will vary.

7. Double the weight and remeasure. Weight __________ Deflection __________ Answer Answers will vary.

8. Is the amount of deflection twice as much as the first amount?

Answer Answers will vary.

9. Whether your answer is yes or no, explain why you think this is so.

Answer Answers will vary but include: increasing weight dampens vibration 10. Quickly remove the weight and again note the oscillations or length of oscillation time.

Oscillations __________ Length of time __________ Answer Answers will vary.

11. Place the original weight back on the edge of the ruler. Quickly remove the weight and again note the oscillations or length of oscillation time.

Oscillations __________ Length of time __________ Answer Answers will vary.

12. Was the result of the second test one-half of the first test?

Answer Answers will vary but include: yes or no

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

13. Explain your results.

Answer Answers will vary but include: moving the weight changes the vibration frequency 14. How does the load placed on the ruler affect the oscillation and deflection rates?

Answer Answers will vary but include: moving the weight changes the vibration frequency

CONCEPT ACTIVITY 46-2 Spring Types Locate as many of the following springs as possible on a vehicle assigned to you by your instructor. Note the type of each spring below.

Year __________ Make __________ Model __________ 1.

Front suspension springs Answer Answers will vary.

2. Rear suspension springs Answer Answers will vary.

3. Hood springs Answer Answers will vary.

4. Trunk/hatch springs Answer Answers will vary.

5. Hood/trunk/fuel door release Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

6. What factors would need to be considered when choosing a spring type for a particular application on a vehicle?

Answer Answers will vary but include: vehicle type, intended use and loads and space available

CONCEPT ACTIVITY 46-3 Shock Absorbers Examine several shock absorbers provided by your instructor.

1.

Note the physical differences in the body and piston rod sizes.

Answer Answers will vary but include: some will be larger or smaller

2. Why are some shocks larger in diameter than others?

Answer Answers will vary but include: increased load capacity 3. Manually compress and extend each shock. Do the shocks compress and extend smoothly?

Answer Answers will vary but include: yes or no 4. Do any compress or extend more easily or harder than the others?

Answer Answers will vary but include: yes or no 5. Do any require a different amount of force to either compress or extend the shock?

Answer Answers will vary but include: yes or no 6. If you answered YES to question 5, why do you think a shock would react differently between compression and extension?

Answer Answers will vary but include: may take more work to resist extension than compression

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

7. How is the energy absorbed by the shock dissipated?

Answer Answers will vary but include: by the oil moving through the chambers 8. Attempt to cycle the shock rapidly between extension and compression. Did the shock get warm, and if so, why?

Answer Answers will vary but include: yes or no, yes due to heat of friction of moving the fluid 9. How can replacing the shocks on a vehicle affect the vehicle’s ride quality?

Answer Answers will vary but include: increased dampening of road shocks

CONCEPT ACTIVITY 46-4 Suspension System Layout Examine the suspension systems, front and rear, on two vehicles as directed by your instructor and record the following information.

Vehicle 1 Year __________ Make __________ Model __________ 1.

Front suspension type Answer Answers will vary based on vehicles used.

2. Rear suspension type Answer Answers will vary.

3. Spring used front/rear Answer Answers will vary.

4. Placement of springs relative to suspension components.

Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

5. Shock absorber location relative to spring location Answer Answers will vary.

6. Diameter of front/rear sway bars Answer Answers will vary.

Vehicle 2 Year __________ Make __________ Model __________ 1.

Front suspension type Answer Answers will vary.

2. Rear suspension type Answer Answers will vary.

3. Spring used front/rear Answer Answers will vary.

4. Placement of springs relative to suspension components Answer Answers will vary.

5. Shock absorber location relative to spring location Answer Answers will vary.

6. Diameter of front/rear sway bars Answer Answers will vary.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 46: Suspension Systems

CONCEPT ACTIVITY 46-5 Electronically Controlled Suspensions Connect a scan tool to a vehicle with an electronically controlled suspension system.

Year __________ Make __________ Model __________ Scan tool __________ Enter communication with the on-board computer system and navigate to the suspension inputs and outputs.

1.

List the inputs for the suspension system.

Answer Answers will vary based on vehicles used but include: ride height, vehicle speed

2. List the outputs controlled by the computer system.

Answer Answers will vary but include: air compressor operation 3. List any active commands the scan tool can control.

Answer Answers will vary but include: increase or decrease ride height Obtain your instructor’s permission to attempt to perform the active commands of the suspension system.

Instructor’s Check __________ 4. If equipped, command the suspension air compressor on, and note any change in ride height.

Answer Answers will vary based on vehicle 5. If equipped, command the air ride system to VENT, and note any change in ride height.

Answer Answers will vary based on vehicle

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13

Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 47: STEERING SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 2 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 47-1 ......................................................................................................... 6 CONCEPT ACTIVITY 47-2 ......................................................................................................... 8 CONCEPT ACTIVITY 47-3 ......................................................................................................... 9

SHORT ANSWER 1.

Describe how a rack and pinion steering and a parallelogram steering system operate.

Answer A parallelogram steering arrangement using either a recirculating ball or worm and roller steering gearbox uses a pitman arm to connect to the steering linkage. The pitman arm transfers motion from the steering gearbox to the linkage, causing the wheels to turn in the correct direction. A rack and pinion steering arrangement has a small pinion gear attached to the end of the steering column that moves a toothed rack attached directly to the tie rods. Movement of the pinion gear causes the rack to push and pull the tie rods and moves the wheels in the desired direction.

2. What precautions must be taken when servicing a steering column?

Answer To not damage the collapsible sections 3. Explain how to perform a dry-park check and why it is needed.

Answer Answers will vary but may include: With the front wheels on the ground or a drive on lift, have an assistant rock the steering wheel side-to-side from center while you inspect the steering linkage for loose components.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

4. List three methods of breaking a ball-and-socket joint taper.

Answer Using a ball joint separator, using a pickle fork, and tapping on the knuckle component to vibrate the joint loose.

5. Describe the operation of a hydraulically power-assisted rack and pinion gearbox.

Answer As the steering wheel is rotated, the wormshaft rotates, causing the ball nut to move up or down the wormshaft. Since the gear teeth on the ball nut are meshed with the gear teeth on the sector shaft, the movement of the nut causes the sector shaft to rotate and swing the pitman arm. The integral power steering system has the spool valve and a power piston integrated with the recirculating ball gearbox. The spool valve directs the oil pressure to the left or right power chamber to steer the vehicle. The spool valve is actuated by a lever or a small torsion bar.

6. Define the term gearbox ratio.

Answer The term “gearbox ratio” refers to the number of input turns required to produce one output turn.

7. What are the benefits of four-wheel steering systems?

Answer All-wheel steering reduces the tendency of production-built cars to either oversteer or understeer, producing near neutral steering under varying road conditions. The advantages gained are increased stability, cornering, and maneuverability and reduced turning radius.

8. What is the purpose of the spool valve in the power-assisted rack and pinion?

Answer The spool valve directs fluid pressure to the left or right power chamber.

MULTIPLE CHOICE 1.

In a rack and pinion steering system, what protects the rack from contamination? a. The inner tie-rod socket b. The outer tie-rod socket c. Grommets d. The bellows boot Answer: d. The bellows boot protects the rack from contamination.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

2. The main job of the idler arm is to ___. a. support the left side of the center link b. support the right side of the center link c. support the Pitman arm d. keep both ends of the steering system level Answer: b. The idler arm supports the right side of the center link and keeps the center link level, but it does not keep the steering system level.

3. Which of the following is true of electric power steering systems? a. The power assist motor can be integrated with the rack gear. b. The assist motor may be located in the steering column. c. The assist motor may drive the pinion gear. d. All of the above.

Answer: d. All statements are true about electric power steering systems. The power

assist motor can be located on the rack gear, in the steering column, or at the pinion gear.

4. Rack and pinion steering ___. a. is lighter in weight and has fewer components than parallelogram steering b. does not provide as much feel for the road as parallelogram steering c. does not use tie-rods in the same fashion as parallelogram steering d. all of the above Answer: a. Rack and pinion steering is lighter and has fewer components.

5. If an electrical defect occurs in the electronic power-steering (EPS) system, ___. a. the system continues to operate normally, but the EPS warning light is illuminated b. the system continues to operate with a slightly reduced power-steering assist c. manual steering remains but there will not be any power assist d. the EPS control unit locks the armature in the steering gear to prevent armature and screw shaft damage Answer: c. The EPS control unit shuts the system down by opening the fail safe and power relays whenever it detects a fault. Manual steering will function.

6. Wandering or poor straight-ahead tracking may be caused by all of the following except ___. a. worn or loose rack mounting bushings b. rack piston seal leaks c. off-center steering gear d. loose or worn tie-rod ends Answer: b. Wandering is caused by loose or worn suspension components, poor wheel alignment, unevenly loaded or overloaded vehicle, loose or damaged steering gear bolts, loose steering column U-joint bolts, loose, worn, or binding steering linkages or tie rod ends, and improper steering gear preload adjustment.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

7. A rack and pinion steering gear ___. a. has tie-rods that connect the rack directly to the steering arms b. is a gear in which the rack needs an idler arm to change the direction of the steering arms c. has inner tie-rod ends that are pressed onto the rack d. has more friction points compared to a parallelogram steering linkage Answer: a. Rack and pinion steering gear tie-rods that connect the rack directly to the steering arms.

8. Which is the least likely cause of hard steering? a. Worn rack spool valve seals b. Insufficient drive belt tension c. Kinked power-steering pressure line d. Loose steering column U-joint Answer: d. A loose steering column U-joint is unlikely to cause hard steering.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that play in the steering gear is the probable cause of a shimmy.

Technician B says that it could be loose steering linkage. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A shimmy is more likely to be the result of looseness in the steering linkage.

2. A vehicle’s steering whines during operation. Technician A says that a loose accessory drive belt can cause this concern. Technician B says air getting into the system from a small leak can cause this. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Whine typically is caused by air in the hydraulic system.

3. An owner’s concern indicates excessive play in the steering wheel: Technician A checks the steering shaft U-joints. Technician B performs a dry park check of the linkage. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Play in the steering can come from the Ujoints or any of the linkage components, such as tie rods.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

4. While discussing steering problems: Technician A says that a “jerky” steering wheel and a “clunking” noise could indicate worn steering column U-joints. Technician B says that lack of assist and a “growling” noise in a fluid-filled steering pump could indicate a hose or pump internal restriction. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Worn U-joints can cause noise and improper feedback to the steering wheel. Power steering noise can be caused by low fluid level, worn pumps, or restricted hoses.

5. While discussing the fail-safe function: Technician A says that the 4WS indicator light is illuminated during the fail-safe function. Technician B says that the rear wheels continue to steer normally when the 4WS control unit enters the fail-safe mode. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. When the system goes into fail-safe, only the front wheels turn in response to the steering wheel.

6. Technician A says that electronically controlled power-steering systems allow for power assistance even when an engine stalls. Technician B says that an electronic rack and pinion system provides power assistance even when the engine stalls. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Only steering systems with an electric motor allow for steering-assist when the engine is off.

7. A vehicle has continual excessive steering effort, but there is no noise and the fluid level in the reservoir is correct: Technician A says that the cause of the problem could be a stuck flow control valve. Technician B says that the cause of the problem fluid bypassing around the rack and pinion flow control valve. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A stuck control valve or leaking control valve can cause hard steering.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

8. While diagnosing a complaint of excessive play in the steering on a vehicle with power steering: Technician A says that the problem could be caused by air in the system.

Technician B says that the problem could be caused by a worn steering shaft U-joint.

Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A worn steering shaft joint can cause excessive play in the steering. Air in the hydraulic system can cause noise and reduced power assist but not play.

9. While diagnosing the problems that can be caused by worn tie-rod ends: Technician A says that they can cause scalloped and scuffed tires. Technician B says that they can cause the vehicle to pull to one side. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Worn tie-rod ends can result in scalloped and scuffed tires.

10. While diagnosing the cause of wheel shimmy: Technician A says that this problem can be caused by loose wheel bearings. Technician B says that this can be caused by binding steering column U-joints. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Binding steering column U-joints are not a probable cause of wheel shimmy.

TECH MANUAL CONCEPT ACTIVITY 47-1 Steering Linkage 1.

Identify the components of the parallelogram linkage system in the following figure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

a. __________ Answer A = center link b. __________ Answer B = pitman arm c. __________ Answer C = outer tie rod d. __________ Answer D = inner tie rod e. __________ Answer E = idler arm f.

__________

Answer F = tie rod sleeve

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

2. Identify the components of the rack-and-pinion linkage system in the following figure.

a. __________ Answer A = steering arm b. __________ Answer B = inner tie rod c. __________ Answer C = bellows d. __________ Answer D = outer tie rod

CONCEPT ACTIVITY 47-2 Steering Linkage Steering ratio is calculated by dividing the degrees of steering wheel rotation by the degrees of movement at the wheels. For example, if 20 degrees of rotation of the steering wheel provided 1 degree of movement at the wheels, the ratio would be 20:1.

1.

Determine the steering ratio of the gearboxes in the following figure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

Gear ratio = __________

Gear ratio = __________

Answer 15:1

12:1

2. What type of vehicles would you expect to have a high gear ratio, and why?

Answer Buses, trucks, large vehicles—to make turning easier 3. What type of vehicles would you expect to have a low gear ratio, and why?

Answer Sports cars—to make steering more precise 4. What are the advantages and disadvantages of a high gear ratio?

Answer Easier steering effort but less precise 5. What are the advantages and disadvantages of a low gear ratio?

Answer More precise steering but increased effort

CONCEPT ACTIVITY 47-3 Manual and Power-Steering Measure the diameter of the steering wheels in several lab vehicles. Note whether each vehicle has manual or power-steering.

Vehicle 1: Wheel diameter __________ Manual/power-steering Vehicle 2: Wheel diameter __________ Manual/power-steering Vehicle 3: Wheel diameter __________ Manual/power-steering

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 47: Steering Systems

1.

Does there appear to be any correlation between the size of the steering wheels and the size of the vehicles?

Answer Answers will vary but include: yes and no

2. Calculate the difference in torque between the smallest and largest diameter wheel, based on 20 pounds of force being used to turn the wheel.

Answer Answers will vary but include: 5–10 ft lbs Nearly all cars and trucks sold today are equipped with power-steering. Power-steering is really an added-on feature to traditional steering systems. The purpose of power-steering is to reduce steering effort. Most systems use a hydraulic pump to supply fluid to the steering gearbox and increase the force supplied by the driver. Some newer vehicles and hybrid vehicles are using electrically operated power-steering systems.

3. If you examine two otherwise identical vehicles, one with manual steering and one with power-steering, would they have the same gearbox steering ratio?

Answer Answers will vary but include: yes or no 4. Explain your answer to question 3.

Answer Answers will vary but include: manual gearbox will have a higher ratio to ease steering effort 5. What are the advantages of electrically operated power-steering?

Answer Answers will vary but include: assist can vary with speed, no fluid to leak, less power demand on engine, improved fuel economy

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 48: RESTRAINT SYSTEMS: THEORY, DIAGNOSIS, AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 48-1 ......................................................................................................... 7 CONCEPT ACTIVITY 48-2......................................................................................................... 8 CONCEPT ACTIVITY 48-3......................................................................................................... 9

SHORT ANSWER 1.

What is the difference between a passive and an active restraint system?

Answer An active restraint requires the vehicle’s occupant to make a manual effort such as buckling a seat belt in place; a passive system operates automatically, with no action required of the occupant to make it functional.

2. What is a crumble zone and how is it used for occupant protection?

Answer A crumple zone is designed into the frame or unibody as an area in which impact forces are absorbed by the frame or body deforming. These areas absorb energy so collision energy is not carried to the passenger compartment.

3. List at least five service precautions that must be adhered to when working on or near air bag systems.

Answer Some of the precautions that ought to be adhered to when serving an airbag system are: • When performing any working on the inside of a vehicle, make sure you are aware of the location of all airbags and exercise caution when working in those areas.

• Wear safety glasses when servicing the air bag system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

•

•

• • • • • •

•

•

Wait at least 30 minutes after disconnecting the battery before beginning any service on or around the air bag system. The reserve energy module stores enough power to deploy the air bag after battery voltage is lost.

Always follow service procedures exactly as given by the manufacturer. Failure to do this can cause the SRS to deploy. Also, if the system is not serviced properly, it may not work when it needs to.

Never disassemble or attempt to repair any parts in order to reuse them, always replace them with new ones.

Handle all air bag sensors with care. Do not strike or jar a sensor in such a manner that deployment may occur.

When carrying a live air bag module, face the trim and bag away from your body.

Do not carry the module by its wires or connector.

When placing a live module on a bench, face the trim and air bag up.

Deployed air bags may have a powdery residue on them. Sodium hydroxide is produced by the deployment reaction and is converted to sodium carbonate when it comes into contact with atmospheric moisture. It is unlikely that sodium hydroxide will still be present. However, wear safety glasses and gloves when handling a deployed air bag. Wash your hands immediately after handling the bag.

A live air bag module must be deployed before disposal. Because the deployment of an air bag is through an explosive process, improper disposal may result in injury and fines. A deployed air bag should be disposed of according to EPA and manufacturer procedures.

Do not use a battery- or AC-powered voltmeter, ohmmeter, or any other type of test equipment not specified in the service manual. Never use a test light to probe for voltage.

4. Describe the two basic types of passenger weight detection sensors used in most vehicles.

Answer After work on the SRS is completed, perform the SRS warning light check. Most passenger weight detection sensors use a bladder placed beneath the seat cushion.

The bladder is connected to a pressure sensor that sends a signal to the control unit for the airbags. The bladder is a silicone-filled gel mat. When there is weight on the seat cushion, pressure is applied to the silicone in the mat. The pressure sensor measures that pressure and converts it to voltage signals. Other weight detection sensors are made up of two sheets of electrodes separated by a spacer. Weight on the seat causes the electrodes to contact each other through a hole in the spacer. The weight on the seat determines the contact area of the sheets. The amount of conductance between the sheets is used to determine weight.

5. Why must you wait for a period of time after disabling the air bag system before servicing can begin?

Answer Answers will vary but may include: To allow the capacitors in the system to discharge.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

6. What service precautions must be taken when working with seat belt pretensioners?

Answer Answers will vary but may include: Do not attempt to measure its resistance.

7. Explain how to safely handle and dispose of an inflated air bag module.

Answer Answers will vary but may include: Wear safety glasses, gloves, and a dust mask or respirator and dispose of per the manufacturer’s procedures.

8. How can the wiring and connectors of SIR systems be identified?

Answer Answers will vary but may include: Its bright yellow color 9. Describe the three types of safing sensors.

Answer The three types of safing sensors commonly used in the air bag systems of current vehicles are: • Roller-Type—These have a roller located on a ramp. One terminal of the sensor is connected to the ramp. The other terminal is connected to a spring contact extending through an opening in the ramp but not touching the ramp. Small springs hold the roller against a stop. During a heavy impact, the roller moves up the ramp and strikes the spring contact. This completes the circuit between the ramp and the spring, and the air bag deploys.

• Mass-Type—This sensor has a normally open set of gold-plated switch contacts and ball. The ball is the sensing mass and is held in place by a magnet. When there is sufficient force, the ball breaks loose and makes contact with the electrical contacts to complete the circuit.

• Accelerometer—This is a piezoelectric element that is distorted during a collision.

It generates an analog voltage that reflects the strength of the deceleration forces.

MULTIPLE CHOICE 1.

Which of the following statements about the SRS warning lamp is not true? a. When the ignition is first turned on, the indicator should turn on and remain on for approximately 6 seconds. b. If the system seems to be able to work correctly, the lamp will stay lit as the engine runs. c. If the lamp flashes or turns off and then turns on again, low source voltage may be indicated. d. A system problem is indicated when the lamp does not turn on when the ignition is initially turned on.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

Answer: b. The SRS warning lamp should turn off after about six seconds after the ignition was turned to the on position. If the system detects a problem, the SRS warning light will remain on 2. What type of seat belt operates automatically with no action required by the vehicle’s occupant? a. Passive restraint b. Retractor c. Active restraint d. Anchorage Answer a. Passive restraints such as seat belts must operate automatically, with no action required by the vehicle’s occupant.

3. Which of the following is false? a. The air bag igniter assembly is a spark plug-type device with two pins that current must jump across. b. The air bag igniter assembly creates a spark that ignites a canister of gas generating zerconic potassium perchlorate. c. The air bag igniter assembly is housed in the module assembly. d. None of the above.

Answer: b. The gas generated to inflate the air bag in this system is nitrogen, not zerconic potassium perchlorate as stated.

4. Which of these statements about air bag sensors is not true? a. Roller-type sensors rely on a roller held in place with a magnet. The circuit is closed when the roller moves and strikes the spring contact. b. Mass-type sensors rely on a ball and a mag-net. The circuit is complete when the ball makes contacts with the electrical contacts in the sensor. c. An accelerometer contains a piezoelectric element that generates an analog voltage in relation to the severity of the deceleration forces. d. An accelerometer also senses the direction of an impact force.

Answer: a. Roller-type sensors rely on the roller that is held against a stop by small springs, not a magnet.

5. Which of the following statements about two-stage air bags is not true? a. When low-pressure air bag deployment is desired, only one squib is fired. b. When the vehicle is in a severe collision and the occupant needs maximum protection, the squib related to the larger container of gas fires. c. For rapid deployment, both squibs fire at the same time. d. To phase in full deployment, one squib is fired, then a few milliseconds later the other is.

Answer: b. During a severe collision, when maximum protection is needed, both squibs fire at the same time.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

6. Which of the following statements about seat belt retractors is not true? a. They stow away the seat belts when they are not being used. b. They allow freedom of movement for the occupant of the seat. c. They can tighten up and pull the occupant back during a crash. d. On some vehicles, they work in concert with the air bag system.

Answer: c. Seat belt retractors can help limit the forward movement of the occupant, but they cannot pull the occupant back during a crash.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that compressed argon gas is often used to deploy passenger-side and side impact air bags. Technician B says that compressed argon gas is used to deploy some driver’s side air bags. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Both argon and nitrogen are used to inflate air bags.

2. Technician A says that seat belt webbing should be replaced if it is bowed. Technician B says that webbing does not need to be replaced if the color has merely faded due to exposure to the sun. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Seat belt webbing should be replaced if it is bowed or if it is discolored due to exposure to the sun.

3. Technician A says that the module assembly will disarm the air bag system if certain faults occur. Technician B says the passenger side air bag may be turned off if there is not enough weight on the passenger seat. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Air bags are typically disabled if faults occur in the system and occupant sensors will turn passenger air bags off if there is insufficient weight on the seat.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

4. While testing seat belt retractors: Technician A grasps a vehicle-sensitive-type belt and jerks it. Technician B grasps a webbing-sensitive-type belt and jerks it. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Test webbing sensitive retractors by jerking on the belt. To test vehiclesensitive retractors requires driving the vehicle and having an assistant test the retractor during a stop.

5. Technician A checks the clock spring electrical connections for signs of damage when replacing a deployed air bag module. Technician B back probes an air bag system with a multimeter to determine if the system is in good working order. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. When repairing air bag systems it is best to also service other related components in assembly groupings. Never back probe an air bag system with a multimeter, or a self- powered test light, unless you want to observe firsthand a very expensive bag deployment.

6. Technician A removes the positive battery cable before servicing any component in the air bag system. Technician B wears safety glasses and protective gloves when handling inflated air bags. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Wear safety glasses and gloves when handling deployed air bags because there may be caustic residue on the module, and two-stage bags may have only deployed the first stage and could still be armed. Disconnect the negative battery cable and wait at least 30 minutes before servicing the air bag system.

7. Technician A says that ignition of the air bag only occurs when an outside sensor and an inside sensor are closed. Technician B says that the safing sensor determines if the collision is severe enough to inflate the air bag. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Multiple sensors must close to initiate an air bag deployment to prevent false activations.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

8. When replacing an air bag module: Technician A says that the steering column clockspring should be maintained in its correct index position at all times. Technician B says that failure to keep the clockspring straight ahead or in the neutral position relative to the steering wheel can cause damage to the enclosure, wiring, or module.

Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The center position of the clockspring must be maintained when installing the air bag module the internal wiring may be damaged.

9. While diagnosing a seat belt that will not buckle: Technician A looks inside the buckle and disassembles it and removes any obstructions that may prevent it from latching onto the belt latch. Technician B replaces the buckle if an obstruction cannot be easily removed from the buckle. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. The buckle should never be disassembled. In most cases, the buckle should be replaced if something is lodged inside.

10. While diagnosing the cause of a constant SRS warning light: Technician A follows the service procedures and connects a jumper wire across designated pins in the DLC then records the flashed codes. Technician B connects a scan tool to the DLC and records the displayed codes. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Most systems have the diagnostic ability to display DTCs when certain terminals of the DLC are jumped and when a scan tool is connected to the system.

TECH MANUAL CONCEPT ACTIVITY 48-1 Identify Restraints Using a vehicle owner’s manual, list the active and passive safety features for a vehicle.

Year __________ Make __________ Model __________

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

1.

Passive restraints Answer Answers will vary but include: air bags, seat belt pre-tensioners

2. Active restraints Answer Answers will vary but include: seat belts 3. Does the vehicle have a passenger side air bag on–off switch?

Answer Answers will vary but include: yes or no 4. Does the vehicle have adaptive (smart) restraints?

Answer Answers will vary but include: yes or no 5. If equipped with adaptive restraints, what sensors are used to determine the number of occupants and their positions?

Answer Answers will vary but include: seat occupant sensors

CONCEPT ACTIVITY 48-2 Restraint Inspection Proper operation of the restraint system is vital for the safety of the occupants of the vehicle.

An inspection of the entire restraint system, seat belts, and air bags, should be performed as part of routine maintenance and if the vehicle has been in any sort of collision.

1.

Inspect the condition of the seat belts, anchors, and latches. Record your findings.

Answer Answers will vary but include: good condition to problems with belts and latches

2. Turn the key to the RUN position and record the action of the restraint system warning light.

Answer Answers will vary but include: on or off

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

3. With your instructor’s permission, start the vehicle and note the restraint warning light. Does the warning light indicate there is a fault with the restraint system?

Answer Answers will vary but include: yes or no If the restraint light remains on or blinking, a fault is present in the system. Connect a scan tool to the vehicle and enter into the restraint system for diagnostic trouble codes (DTCs). If a scan tool is not required for code retrieval, proceed to step 5.

4. Scan tool used Answer Answers will vary but include: Snap-On, Autel 5. Restraint system DTCs Answer Answers will vary.

6. Describe the restraint system deactivation process for the vehicle being inspected.

Answer Answers will vary but include: disconnecting battery negative cable and waiting several minutes 7. What color is the wiring identifying air bag system components?

Answer Answers will vary but include: yellow

CONCEPT ACTIVITY 48-3 Air Bag Service Here are some very important guidelines to follow when working with and around air bag systems. These are listed with some key words left out. Read through these and fill in the blanks with the correct words.

1.

Wear ___ when servicing an air bag system and when handling an air bag module.

Answer safety glasses

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 48: Restraint Systems: Theory, Diagnosis, and Service

2. Wait at least ___ minutes after disconnecting the battery and before beginning any service. The reserve ___ module is capable of storing enough power to deploy the air bag after battery voltage is lost.

Answer 5; energy 3. Always handle all ___ and other components with extreme care. Never strike or jar an air bag sensor, especially when the battery is connected. Doing so can cause deployment of the air bag.

Answer sensors 4. Never carry an air bag module by its ___ or ___, and when carrying it, always face the trim and air bag ___ your body. When placing a module on a bench, always face the trim and air bag ___.

Answer wiring; connector; away; up 5. Deployed air bags may have a powdery residue on them. ___ is produced by the deployment reaction and is converted to ___ when it comes into contact with the moisture in the atmosphere. Although it is unlikely that harmful chemicals will still be on the bag, it is wise to wear ___ and ___ when handling a deployed air bag.

Answer Sodium hydroxide; sodium carbonate; safety glasses; gloves 6. Immediately wash your ___ after handling a deployed air bag.

Answer Answers will vary.

7. A live air bag must be ___ before it is disposed. A deployed air bag should be disposed of in a manner consistent with the ___ and manufacturer’s procedures.

Answer Deployed; EPA 8. Never use a battery- or AC-powered___, ___, or any other type of test equipment in the system unless the manufacturer specifically says to. Never probe with a(n) ___ for voltage.

Answer voltmeter; ohmmeter; test light

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

Solution and Answer Guide ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 49: WHEEL ALIGNMENT

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 49-1 ......................................................................................................... 7 CONCEPT ACTIVITY 49-2......................................................................................................... 8 CONCEPT ACTIVITY 49-3......................................................................................................... 9 CONCEPT ACTIVITY 49-4 ....................................................................................................... 11 CONCEPT ACTIVITY 49-5........................................................................................................ 12 CONCEPT ACTIVITY 49-6 ....................................................................................................... 14

SHORT ANSWER 1.

Define camber.

Answer Camber is the tilting of the tire away from vertical. Positive camber is when the top of the tire leans away from the vehicle and negative camber is when the top of the tire leans in toward the vehicle.

2. What tire wear pattern will result from excessive toe-in?

Answer Excessive toe-in causes the portion of the tread toward the centerline of the car to wear, this is called feathered wear.

3. What can be caused by excessive negative caster?

Answer Excessive negative caster can cause wandering, unintentional weaving, and instability at higher speeds.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

4. Describe the difference between toe-in and toe-out.

Answer Toe is the distance comparison between the leading edge and trailing edge of the tires.

If the leading edge distance is less than the trailing edge, there is toe-in; if it is greater, there is toe-out.

5. Describe thrust angle and why it is important for wheel alignment.

Answer Thrust angle is the angle at which the rear axle is pointing. It is important because the thrust angle will push the vehicle to one side or the other if incorrect, resulting in the front wheels having to steer against the rear axle’s direction. It is the difference between rear toe and the geometric centerline of the vehicle. The vehicle tends to travel in the direction of the thrust line rather than straight ahead.

6. What can cause incorrect toe-out-on-turns?

Answer Excessive toe-out can cause the car to wander and lose stability on slick surfaces because the tire is partially sliding, rather than rolling, on the road surface. It is commonly caused by a bent steering arm or steering knuckle.

7. In what direction must the bottom of a tire and wheel assembly be moved to add more positive camber?

Answer The bottom of the tire and wheel assembly must be moved inward in order to add more positive camber.

8. What is scrub radius and why is it important?

Answer Scrub radius is the distance between the center of the tire and where the SAI angle intersects the ground. The scrub radius must be equal on both sides of the vehicle otherwise the vehicle will pull to one side.

9. Define the term “tracking” as it applies to vehicle handling.

Answer “Tracking” is a term used to describe the direction the rear wheels would travel if unaffected by the front wheels. Correct tracking means that all of the wheels are in their correct locations and conditions and aligned so the rear wheels follow directly behind the front wheels while moving in a straight line.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

10. What items should be inspected on a vehicle with incorrect caster and camber readings but for which no provision for adjustment is provided?

Answer Answers will vary but may include: Strut, steering knuckle, control arms, frame.

11. Which alignment angle is typically used to compensate for road crown and why?

Answer Caster, because it does not cause tire wear.

12. Explain how ride height affects wheel alignment Answer Answers will vary but may include: All alignment angles change as the vehicle moves up or down. If ride height is not correct, the angles will be off.

13. What is the correct sequence for adjusting alignment angles during a four-wheel alignment?

Answer During a four-wheel alignment, adjustments should be made in this order: (1) rear camber and toe, (2) front caster, (3) front camber, and (4) front toe

MULTIPLE CHOICE 1.

Which of the following is a good definition of SAI? a. Forward tilt of the top of the steering knuckle b. Rearward tilt of the spindle steering arm. c. Inward tilt of the top of the ball joint or strut d. Outward tilt of the top of the ball joint or strut Answer: c. SAI is the angle formed between true vertical and a line drawn between the steering pivot points as viewed from the front.

2. Unequal SAI angles on the left and right sides of the front suspension may cause ___. a. tread wear on the front tires b. brake pull during sudden stops c. ball joint wear d. steering wander while driving straight ahead Answer: b. If the SAI angles are unequal side-to-side, torque steer, brake pull, and bump steer.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

3. While driving straight, a FWD car pulls to the right. The most likely cause is ___. a. more positive camber on the left front wheel compared to the right front wheel b. sagged front springs and improper front-wheel toe setting c. less positive caster on the right front wheel compared to the left front wheel. d. the SAI on the right front wheel is 1½ degrees more than the SAI on the left.

Answer: c. Unequal caster angles will cause the vehicle to steer toward the side with less caster.

4. Technician A says toe is the most critical tire- wearing angle. Technician B says camber is the most critical tire-wearing angle. Who is correct? a. Technician A. b. Technician B. c. Both A and B. d. Neither A nor B Answer: a. Technician A.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that negative caster provides directional stability. Technician B says that positive caster results from excessive positive camber. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Negative caster decreases stability and positive caster increases stability. A positive camber setting will not make caster positive unless both are set positive.

2. Technician A says that the purpose of the steering wheel holder is to make sure that the steering wheel is centered after the alignment. Technician B says that if the steering wheel is not centered after an alignment, it should be pulled off the column and positioned correctly. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. The steering wheel lock centers the steering wheel during alignment. If the toe is adjusted, the steering wheel may not be centered after alignment and a recentering procedure is then required. Centering the wheel by removing and repositioning it should never be an option.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

3. Technician A says that the presence of a thrust angle can cause poor directional stability on ice, snow, or a wet pavement. Technician B says that it can also increase tire wear because the front wheels fight the rear ones for steering control. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Incorrect thrust angle prevents the front and rear of the vehicle from being exactly parallel with each other, which can cause control issues and increase tire wear.

4. Technician A says that camber changes as the suspension moves up and down.

Technician B says that camber changes as the vehicle is loaded and the suspension sags under the weight. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Any movement of the vehicle and suspension height will cause the camber to change. Camber is constantly changing as the vehicle is driving.

5. Technician A says that caster can be adjusted on nearly all front suspensions.

Technician B says that toe can only be adjusted on front suspensions. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Caster is not adjustable on many FWD and some RWD suspension types. Toe is adjustable on all types of front suspension systems.

6. Technician A says that on FWD vehicles, the front wheels toe-out while the rear wheels on an independent suspension try to toe-in as the vehicle moves ahead.

Technician B says that on RWD vehicles, the front wheels tend to toe-in while the rear wheels toe-out in response to rolling resistance and suspension compliance. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. FWD vehicles tend to toe-in while driving and RWD vehicle tend to toe-out while driving.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

7. Technician A says that if caster at both wheels is not equal, the vehicle will tend to drift toward the side with the most positive caster. Technician B says that if camber is not the same on both wheels, the vehicle will pull toward the side with the most positive camber. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. When camber is unequal, the vehicle will tend to pull toward the side with the most positive camber.

8. While discussing front-wheel caster: Technician A says that high amounts of positive caster increases the steering effort and can increase tire wear. Technician B says that excessive negative caster causes front-wheel shimmy. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Negative caster will not cause wheel shimmy, excessive positive caster will.

9. While performing a prealignment inspection: Technician A says that improper frontwheel bearing adjustment may affect wheel alignment angles. Technician B says that worn ball joints affect only the camber angle. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Ball joints, as well as all suspension and steering parts (including wheel bearings), can have an effect on all alignment angles.

10. While performing a prealignment inspection: Technician A says that a prealignment inspection should include checking the vehicle interior for heavy items. Technician B says that tools and other items normally carried in the vehicle should be included during an alignment. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The vehicle should be aligned as it is normally operated and following the manufacturers procedures regarding loading.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

TECH MANUAL CONCEPT ACTIVITY 49-1 Reference Lines An imaginary line running through the center of the vehicle is called the geometric centerline, often referenced as Figure 49-1. The centerline, also called the thrust line, should run straight through the center of the vehicle.

FIGURE 49–1 Vehicle centerline.

1.

How would the vehicle respond if the thrust line deviated from the center of the vehicle?

Answer The vehicle would drive in the direction of the thrust line.

2. List at least three problems that can cause the thrust line to be off center.

Answer incorrect rear-end alignment, bent frame/body, shifted rear axle, bent rear axle 3. What might the customer complaint be for a vehicle with this problem?

Answer Pull to one side and an off-center steering wheel

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

CONCEPT ACTIVITY 49-2 Camber For maximum tread life and tire traction, the tires should be perpendicular to the ground. This means that viewed from the front or the rear, the tires would be vertical, or 90 degrees from the ground. The tilt away from vertical is called camber. Camber is often adjusted on both the front and rear wheels.

1.

Identify the positive and negative camber in the figure below (Figure 49-2).

FIGURE 49–1 Label camber.

Answer Negative camber, 0 camber, positive camber 2. What problems will excessive negative camber cause?

Answer Tire wear on the inside portion of the tire and can cause a pull.

3. What problems will excessive positive camber cause?

Answer Tire wear on the outside portion of the tire and can cause a pull.

4. Explain how excessive camber can cause a vehicle to pull.

Answer The tire will try to travel in a cone shaped path, pulling the vehicle toward the direction of tilt.

5. What components will affect camber?

Answer Springs, ball joints, control arms, control arm bushings, strut, frame, spindle, steering knuckle

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

6. A tire that is vertical has how much camber?

Answer Zero degrees

CONCEPT ACTIVITY 49-3 Caster Nearly every person has experience with two very common examples of the caster angle: a bicycle and the wheels on a shopping cart (Figure 49-3 and Figure 49-4).

FIGURE 49–3 An example of caster on the wheels of a bicycle.

FIGURE 49–4 An example of caster on the vehicle.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

1.

Explain how the front forks of a bicycle demonstrate caster.

Answer The inclination of the forks places the load out in front of the tire which causes the tire to track toward that spot.

NOTE: The following questions are not intended to cause anyone to operate a bicycle in any unsafe manner. Do not ride a bicycle without the proper safety apparel and follow all of the manufacturer’s warnings and guidelines.

2. If you have ever ridden a bicycle and removed your hands from the handlebars, how did the bike respond?

Answer Answers will vary.

3. Why did the bike behave as you described?

Answer Answers will vary but include: positive caster creates stability 4. How do shopping cart wheels, called casters, respond when pushing a cart?

Answer Answers will vary but include: they do not follow a straight line 5. Why do some casters flop around wildly when the cart is being pushed?

Answer Answers will vary but include: negative caster does not track straight ahead Caster is measured as positive, negative, or at zero degrees. Positive caster allows for better tracking and stability, whereas negative caster allows for easier steering.

6. The bicycle is an example of __________ caster.

Answer Positive—more stable for straight ahead tracking 7. The shopping cart caster is an example of __________ caster.

Answer Negative

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

8. Which angle do you think is used by most vehicles, and why?

Answer Answers will vary but include: positive—more stable for straight ahead tracking 9. What could be the customer complaint on a vehicle with the caster angles out of specification?

Answer Pull or drift to one side 10. What components affect caster?

Answer Springs, ball joints, control arms, control arm bushings, strut, frame, spindle, steering knuckle 11. What affect will caster have on tire wear?

Answer Usually no effect

CONCEPT ACTIVITY 49-4 Toe The angle that is most responsible for tire wear is the toe angle. Toe can be either in or out or measured in degrees positive and negative (Figure 49-5). Toe is often adjusted on both the front and rear wheels.

FIGURE 49–5 Front wheel toe.

1.

Explain why toe is the most tire-wearing angle.

Answer Because the whole tire contact patch is scuffing when toe is incorrect

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

2. If the front edges of the tires are closer together than the rear edges, this would indicate toe.

Answer Toe-in 3. If the rear edges of the tires are closer together than the front edges, this would indicate toe.

Answer Toe-out 4. What is the best toe setting as the vehicle is driving on the road?

Answer Zero toe 5. Why do some vehicles have a toe angle specification for toe-in and some for toe-out?

Answer To compensate for either FWD axle twist (shortening) or the frictional load on RWD steering components that force the tires out slightly 6. What components affect toe?

There are also several other alignment angles used for diagnostic purposes that are not generally adjustable.

Answer Springs, ball joints, control arms, control arm bushings, strut, frame, spindle, steering knuckle, tie rods, steering gear mountings

CONCEPT ACTIVITY 49-5 Diagnostic Angles Steering axis inclination (SAI), included angle, scrub radius, and turning radius (sometimes called toe-out-on-turns) are not adjustable but can be used for diagnosing alignment and tire wear concerns.

Steering axis inclination is the line through the steering axis, either the upper and lower ball joints or upper strut mount and lower ball joint, and true vertical. SAI plus or minus camber equals the included angle. SAI can be used to diagnose bent suspension components.

Included angle is determined from the SAI readings. SAI is also used for determining scrub radius. Scrub radius is the distance from the center of the tire to where the SAI angle intersects the ground (Figure 49-6 and Figure 49-7).

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

FIGURE 49–6 SAI and scrub radius.

FIGURE 49–7 SAI.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

Turning radius is built into the vehicle so that during turns the inside wheel turns at a slightly sharper angle. This is necessary because the inside tire has to turn in a smaller radius than the outside tire. This angle prevents the tire from scrubbing across the road when turning (Figure 49-8).

FIGURE 49–8 Turning radius is the amount one wheel turns more sharply than the other.

1.

List three suspension components that will affect SAI. Answer

Answers will vary but may include struts, steering knuckle, spindle, control arms.

2. Explain how changing wheels can affect scrub radius.

Answer Answers will vary but may include scrub radius is based on SAI and the center of the tire contact. Changing the wheel offset can change where the wheel center is, thereby changing scrub radius.

3. Explain how the total toe setting could be correct but the turning radius is incorrect.

Answer A bent steering component will affect turning radius but still allow for total toe to correctly set.

CONCEPT ACTIVITY 49-6 Prealignment Inspection When wheel alignment is being checked and adjusted, it is important that certain procedures be performed before checking the alignment.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 49: Wheel Alignment

1.

Tire pressure must be set correctly. How can incorrect tire pressure affect the alignment?

Answer Tire pressure can affect vehicle ride height, which if incorrect, will affect the alignment.

2. Wheel bearings must be in good condition and not have excessive play. How can a loose or improperly adjusted wheel bearing affect the alignment?

Answer A loose wheel bearing will allow slight changes in camber and toe 3. List the suspension components that must be checked and in good condition before an alignment can be performed.

Answer Springs, ball joints, control arms, control arm bushings, strut, frame, spindle, steering knuckle, 4. List the steering components that must be checked and in good condition before an alignment can be performed.

Answer Tie rods, steering gear mountings, steering gear, idler arm, pitman arm, steering column u-joints, strut mounting plates 5. If a vehicle has worn-out springs, what symptom may be evident?

Answer Low ride height, bottoming out over bumps/dips, tire wear 6. Explain why a wheel alignment cannot be performed if the springs are too weak.

Answer Incorrect ride height will affect wheel position and there may not be enough adjustment for caster and camber to bring the angles back into specs.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 50: BRAKE SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 50-1 ......................................................................................................... 6 CONCEPT ACTIVITY 50-2......................................................................................................... 9 CONCEPT ACTIVITY 50-3........................................................................................................ 13

SHORT ANSWER 1.

Explain why bleeding air out of a hydraulic system is so important.

Answer When air is present in the hydraulic system, the amount of force that may be transmitted by the brake fluid is diminished because the air compresses as fluid pressure increases.

2. Explain why modern hydraulic braking systems are dual designs, and why this is important.

Answer Brake systems on late model cars are dual-circuit designs using a tandem master cylinder that separates the system into two circuits. The piston in each circuit is responsible for applying the brakes for two of the wheels. This provides a safety factor so that when one circuit fails, the other circuit can continue to provide partial braking.

3. Describe the functions of the hydraulic system combination valve.

Answer The combination valve combines the functions of the metering, pressure differential, and proportioning valves into one assembly. The metering valve functions to delay application of the disc brakes until the drum brakes have sufficient pressure to also apply; the pressure differential valve functions to alert the driver of a loss of pressure in one of the brake circuits; the proportioning valve functions to limit unwanted rear wheel lock-up during forceful application of the brakes.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

4. List four safety precautions you should observe when working with brake fluid.

Answer Answers will vary but may include: Use fender covers to keep off pain, do not get on plastics or wiring, do not leave the container open, do not reuse old fluid, and wear safety glasses, wear gloves.

5. What is the purpose of the master cylinder replenishing port?

Answer The replenishing port lets fluid pass between each pressure chamber and its fluid reservoir during operation.

6. Explain why a height-sensing proportioning valve is used on some vehicles.

Answer Height-sensing proportioning valves are needed because the weight on the rear axle of a vehicle can vary greatly from an unloaded to fully loaded condition. These weight extremes affect braking balance and the amount of hydraulic pressure needed at the rear drum brakes. Because the height of the vehicle also changes with the load at the rear of the vehicle, a proportioning valve that adjusts itself according to vehicle height is an effective way to provide variable pressure control to the rear brakes.

7. Contrast the three types of power brake systems.

Answer Answers will vary but may include: Vacuum boost systems use a vacuum booster to apply assist. A vacuum booster uses vacuum and atmospheric pressure to increase brake application force to the master cylinder and reduce driver effort. Hydraulic assist systems use hydraulic pressure from the power steering pump to increase brake application pressure to the master cylinder.

8. What is a typical brake fluid change interval specification?

Answer Answers will vary but may include: 12 months or 15,000 miles to every 60,000 miles 9. Explain how vacuum is used to provide a power assist.

Answer In nature, a higher pressure will always move toward a lower pressure. The force and the speed at which the higher pressure moves depends on the pressure differential or the difference between the high and the low pressures. The pressure differential exerts a force on the diaphragm of the booster and this force is used to apply the brakes.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

MULTIPLE CHOICE 1.

The purpose of the master cylinder is to ___. a. generate the hydraulic pressure needed to apply the brake mechanisms b. automatically pump the brakes during panic stops c. apply braking power when wheel slippage occurs d. all of the above Answer: a. The master cylinder generates the hydraulic pressure used to apply the brakes.

2. Which of the following can lead to brake hose failure? a. Twisting during installation b. Stressing the hose during installations c. Deterioration from heat and contaminants d. All of the above Answer: d. All of the above 3. Which type of brake requires greater application force and is commonly used with power-boost units? a. Drum b. Disc c. Parking d. None of the above Answer: b. Disc brakes require higher application pressure and are commonly used with a power brake booster.

4. Which of the following is not a factor in determining the effectiveness of a brake system? a. Heat dissipation b. Lubricant c. Pressure d. Frictional contact area Answer: b. The effectiveness of the brakes depends on all of the listed factors except lubrication.

5. Which of the following could cause an extremely hard brake pedal? a. Air in the system b. Excessively worn brake pads c. Use of the wrong fluid d. A leaking diaphragm in the vacuum power booster Answer: d. A leaking diaphragm in a vacuum-assist booster would provide little or no assist, resulting in an extremely hard pedal.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

ASE-STYLE REVIEW QUESTIONS 1.

A vehicle’s power brakes are grabbing: Technician A says that the most likely cause is the power brake booster. Technician B says that the most likely cause is greasy linings or scored drums. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Grabbing brakes are most likely caused by greasy linings or scored drums.

The power unit can cause grabbing brakes, but it is the least likely, not the most likely, cause.

2. While discussing what affects the amount of pressure exerted by the brakes: Technician A says that the shorter the line, the more pressure there will be. Technician B says that braking force will increase if the size of the pistons in a master cylinder is increased. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither of the technicians is correct. The length of the line does not affect pressure; when a force is applied to a confined liquid such as brake fluid, pressure will be equal in all areas of the fluid regardless of the length of the lines. A larger master cylinder piston would result in lower, not higher, fluid pressure (pressure = force/area) and less force applied to the brake shoes (force = pressure x area).

3. The metering valve portion of a combination valve fails: Technician A says that this means the entire combination valve must be replaced. Technician B says that the metering part can be repaired. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Combination valves are replaced as a unit.

4. While discussing quick take-up master cylinders: Technician A says that this design allows for increased braking power. Technician B says that this design is only used on drum brake systems. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. The quick-take-up master cylinder is used on disc/drum systems using low drag calipers and is not designed to increase braking power.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

5. While bleeding a brake system: Technician A loosens the brake line fitting at the master cylinder to bleed the system if a bleeder screw is seized and cannot be loosened. Technician B uses shop air to push the fluid and air from the wheel units to the master cylinder. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. When the bleeder valve is seized, the wheel cylinder should be replaced. Using shop air to push fluid and air from the wheels to the master cylinder would increase the amount of air in the system, not remove it.

6. The basic frictional parts of a brake system are being discussed: Technician A says that the harder the frictional parts are pushed together, the greater the friction.

Technician B says that the harder the frictional parts are pushed together, the more heat is developed. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Increasing pressure against the friction materials will increase both the amount of friction and the heat generated.

7. Vehicle dynamics during braking are being dis-cussed: Technician A says that the rear of the car rises during braking. Technician B says that the front of the car lowers during braking. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

8. Pressure bleeding is being discussed: Technician A says that metering and combination valves must be held open using a special tool during the bleeding operation to ensure good results. Technician B says that the pressure bleeder requires special adapters to connect it to the master cylinder reservoir. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

9. Technician A says that the master cylinder should be bled before any individual wheel assembly. Technician B says that the bleeder screw should be closed before the brake pedal is released during manual bleeding of the system. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct.

10. The hydraulic system of the hydro-boost and Powermaster is being discussed: Technician A says that the hydro-boost uses a power-steering pump. Technician B says that the Powermaster uses an electric motor-driven vane pump. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Hydraulic assist can be provided by either a power steering pump or a separate electric pump.

TECH MANUAL CONCEPT ACTIVITY 50-1 Leverage Anyone who drives can tell you that to slow or stop the vehicle, all you have to do is let off the accelerator and press the brake pedal. But how many drivers understand what takes place each time that pedal is pressed? The pedal itself is an application of one of the oldest forms of machines, the lever. Known from the ancient world, the lever is not only one of the oldest machines but also a very simple machine. A lever is used to apply force to gain mechanical advantage, such as moving a heavy object by increasing or decreasing the distance over which the force is applied. Many playgrounds have a teeter-totter where children can sit on a long board supported in the middle by a fulcrum. If two people of the same weight sit the same distance apart from the middle, the teeter-totter will balance, and both people will be suspended off the ground at equal heights. But what happens if one person weighs more than the other? To offset the imbalance, the heavier person must move forward, closer to the middle, or the lighter person must move further away from the middle, to the very edge of the board (Figure 50-1).

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

FIGURE 50–1 Balance on a teeter-totter.

1.

If the fulcrum stays in the middle, why must one person move to offset the imbalance?

Answer Answers will vary but include: to offset the weight difference

2. If the two people stay in place, how must the fulcrum move to rebalance the teetertotter?

Answer Answers will vary but include: closer to the heavier weight A teeter-totter is an example of a first-class lever. In a first-class lever, the fulcrum is located between the load and the effort (Figure 50-2). Using a shovel to dig up a plant is another example of a first-class lever in action.

FIGURE 50–2 Example of a first-class lever.

Construct a teeter-totter balance, using a standard ruler and a C or D battery mounted in the middle as a fulcrum (Figure 50-3). Locate several items from the lab to balance on the ruler.

FIGURE 50–3 Constructing a simple teeter-totter.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

3. With the fulcrum in the middle, what were the distances from the center for each item to achieve balance?

Answer Answers will vary.

4. Place the items to be balanced at the ends of the ruler and move the fulcrum to achieve balance. How much did the fulcrum move to balance the objects?

Answer Answers will vary but include: several inches The brake pedal in a car operates as a second-class lever. With a second-class lever, the fulcrum is at one end of the lever instead of the middle. The effort is applied to the other end of lever, and the force is applied somewhere between the effort and the fulcrum (Figure 504). Look under the dashboard of several vehicles to see how the brake pedal is mounted.

Notice that the top of the pedal is the mounting point, which acts as the fulcrum. Below the fulcrum, the pedal pushrod is mounted and extends forward through the firewall, to the brake booster and/or master cylinder. The footpad at the bottom of the pedal is where the effort is applied.

FIGURE 50–4 The brake pedal is a lever.

Measure the length of the pedal between the pushrod and fulcrum and the pushrod and the lowest point of the pedal for several vehicles.

5. Pushrod to fulcrum length __________

Pushrod to pedal length __________

Answer Answers will vary but include: 8 inches and 2 inches 6. Pushrod to fulcrum length __________

Pushrod to pedal length __________

Answer Answers will vary but include: 6 inches and 3 inches Because the force is between the fulcrum and the effort, the resulting force is determined by the distance below the force divided by the distance above the force (Figure 50-5). If a brake pedal is mounted so that there is 2 inches above the pushrod to the fulcrum and 10 inches from the pushrod down to the end of the pedal, the ratio of force can be determined. Use the © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

following formula: R = da/db, where R is the ratio, da is the distance from the pushrod to the end of pedal, and db is the distance from the pushrod to the fulcrum. Because distance a is 10 inches and distance b is 2 inches, 10 divided by 2 equals 5. Therefore, the ratio of force applied by this pedal is 5 to 1, or 5:1. This means that the force applied to the brake pedal will increase by a factor of 5. Using the measurements of the brake pedals from questions 5 and 6, determine the ratio of force for each of the two vehicles.

FIGURE 50–5 Determine the advantage gained by the brake pedal.

7. da/db = __________

Ratio __________

Answer Answers will vary but include: 4:1 8. da/db = __________

Ratio __________

Answer Answers will vary but include: 2:1 As you can see, the brake pedal and its mounting design reduce the amount of effort needed from the driver. This reduction of effort is beneficial for the driver, as it will reduce fatigue during vehicle operation.

CONCEPT ACTIVITY 50-2 Hydraulics Even though the force applied to the brake pedal is increased, it is necessary for the hydraulic system to further increase the force and apply it in a manner that will safely slow and stop the vehicle.

Hydraulics refers to using fluids to perform work. Fluids can be pressurized but cannot be compressed. By pressurizing a fluid in a closed system, the fluid can transmit both motion and force. This is accomplished by using pistons in cylinders of different sizes to either increase force or increase movement. Whenever there is an increase in force, there will be a decrease in the amount of movement. Conversely, when there is an increase in movement, there will be a decrease in force. In this manner, a hydraulic system is like the lever we studied before. To increase the force needed to be applied to an object, more distance or movement needs to be applied. Locate two items around your lab that rely on hydraulics to operate.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

1.

Item 1__________ How does this item use hydraulics? __________ Answer Answers will vary but include: floor jack, to lift heavy cars with little user effort

2. Item 1 __________ How does this item use hydraulics? __________ Answer Answers will vary but include: vehicle lift, to life heavy cars using hydraulic pump A simple hydraulic system contains two equal-sized containers of a liquid with two equalsized pistons. The two containers are connected with a hose or tubing (Figure 50-6). If one piston is pushed downward with 100 pounds (45 kg) of force and moves down 10 inches, the piston in the second container will move upward 10 inches with the same 100 pounds (45 kg) of force. Because the pistons are the same size, any force and movement imparted on one piston will cause the same reaction to the second piston.

FIGURE 50–6 Pascal’s Law of hydraulics.

Where the use of hydraulics really provides advantage is when the sizes of the pistons are different, and the resulting force and movement can be increased or decreased as needed.

The pressure generated by the piston is determined by its size. Input pressure is found by dividing the applied force by piston size, or P = F/A. The smaller the input piston surface area, the larger the force will be from that piston. The larger the input piston surface area, the lesser the force will be from that piston (Figure 50-7). Conversely, the force of the output piston is proportional to the pressure against the surface area of the piston. An output piston that is larger than the input piston will move with greater force than the input but with less distance moved. To examine this principle, we will look at what is known as Pascal’s Principle or Law.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

FIGURE 50–7 Using hydraulics for mechanical advantage.

If the smaller piston on the left is our input piston and has a surface area of 1 square inch (6.45 cm2) and the larger piston is our output piston and has an area of 10 square inches (65.5 cm2), we can calculate the forces and movements quite easily. Suppose a force of 100 pounds (45 kg) is exerted on our input piston, moving it downward 1 inch (2.54 cm). Using P = F/A, we can calculate P = 100/1, or 100 psi. Our output piston, which has a surface area of 10 square inches, will receive 100 pounds of pressure per square inch. This will result in an output force by the second piston of 1,000 pounds. However, because our output force has increased, our output movement will decrease. The larger piston will move 1/10th of the distance of the input piston; because the force was multiplied by 10, the distance will be divided by 10 as well. The 1 inch of movement of the input piston (piston 1) turns into 1/10th of an inch of movement at the output piston (piston 2). To calculate the forces and movement in a hydraulic circuit, use the following formulas: P1 = F1/A1 for piston 1 pressure F2 = A2/A1 · F1 for piston 2 force P2 = F2/A2 for piston 2 pressure To practice using these principles, complete the following activity.

Calculate the forces and movements of a two-piston hydraulic circuit with an input piston of 2 square inches and an output piston of 10 square inches.

3. Input distance __________ Output distance __________

Input force __________ Output force __________

Answer Answers will vary based on input information Calculate the forces and movements of a two-piston hydraulic circuit with an input piston of 2 square inches and an output piston of 1 square inch.

4. Input distance __________ Output distance __________

Input force __________ Output force __________

Answer Answers will vary based on input information

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

The pushrod from the brake pedal pushes pistons inside the brake master cylinder. The master cylinder provides the pressure in the brake system. The force applied to the brake pedal, the ratio of brake pedal force multiplication, and master cylinder piston size all determine how much pressure will be developed in the brake system. The size of the output pistons at the calipers and wheel cylinders, along with the brake system pressure, determine the final output force for the brakes. Use the diagram below to determine brake system pressure. Remember from Concept Activity 50-1, that da is the distance from the pushrod to the end of the pedal, and db is the distance from the pushrod to the fulcrum (Figure 50-8).

FIGURE 50–8 Finding the mechanical advantage.

5. Input force to pedal __________ Output force __________

da __________ db __________ Hydraulic system pressure __________

Answer Answers will vary.

6. Input force to pedal __________ Output force __________

da __________ db __________ Hydraulic system pressure __________

Answer Answers will vary.

Obtain a sample of syringes from your instructor. Fill each syringe approximately halfway with water. Connect a hose between two different syringes. Push the plunger of one syringe and note the reaction of the other. Perform this exercise several times, using different sizes of syringes as the input and output pistons.

7. Syringe 1: Diameter __________ Syringe 2: Diameter __________

Distance moved __________ Distance moved __________

Answer Answers will vary based on items used.

8. Syringe 1: Diameter __________ Syringe 2: Diameter __________

Distance moved __________ Distance moved __________

Answer Answers will vary based on items used.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

9. Syringe 1: Diameter __________ Syringe 2: Diameter __________

Distance moved __________ Distance moved __________

Answer Answers will vary based on items used.

10. Syringe 1: Diameter __________ Syringe 2: Diameter __________

Distance moved __________ Distance moved __________

Answer Answers will vary based on items used.

CONCEPT ACTIVITY 50-3 Friction Once the hydraulic system generates the pressure to actuate the pistons in the calipers and wheel cylinders, it is the job of the lining surfaces to slow the vehicle. The lining surfaces consist of the brake rotor or disc, brake pads, brake drum, and brake shoes. Brake pads are squeezed together against the rotor by the brake caliper. Brake fluid, under pressure from the hydraulic system, pushes on the caliper piston. As the piston moves out, pushing the inner pad against the rotor, the caliper slides inward, pressing the outer pad against the outside of the rotor. On drum brakes, the fluid pushes on two equal-diameter pistons in the wheel cylinder. The pistons move out, pressing the brake shoes against the inside surface of the brake drum.

Brake pads and shoes create a lot of friction when applied; this in turn creates a lot of heat.

Heat is a natural by-product of friction. Rub your hands together briskly and note how fast your skin warms.

1.

Why does rubbing your hands together create heat?

Answer The contact between the two moving surfaces has friction. As your hands move back and forth the resistance to their movement generates heat.

2. Wet your hands with some water and rub them together briskly again. How did the water change the result?

Answer Answers will vary but include: less heat is created due to reduced friction In automotive applications, friction is used or offset by various design qualities, such as the brake system which uses friction to stop the vehicle; the friction of moving fluids such as motor oil and transmission fluid; friction between the vehicle and the air in which it is traveling—called drag; and friction between the tires and the ground. Refer to Concept Activity 3-5 about friction.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

Friction is created when uneven surfaces in contact with each other start to move relative to each other. Although the two surfaces may appear smooth, there are slight imperfections that resist moving against each other. The amount of force required to move one object along another is called the coefficient of friction (CoF). Simply put, the CoF is equal to the ratio of force to move an object divided by the weight of the object, CoF = F/M. Although several factors affect the CoF, such as temperature and speed, we will use a simple example of two bodies moving against each other. Imagine you have a 100-lb (45 kg) block of rubber on the floor of your lab. The force required to slide the block of rubber over concrete would be large.

If it takes 100 lb (45 kg) of force to slide the block, the CoF would be 100/100, or 1.0. Imagine the same block of rubber now sitting on the floor of an ice hockey rink. If it only takes 25 lb (11 kg) of force to slide the block, what would the CoF be?

3. 25/100 =__________ Answer .25 To experiment with the CoF of various objects in your lab, you can make a small force gauge using an ordinary ballpoint pen, a rubber band, tape, and a paper clip. Assemble the parts as shown in Figure 50-9:

FIGURE 50–9 Pulling an object with the paper clip will cause the rubber band to lengthen. The amount of lengthening can be measured and recorded for comparison.

Attach the paper clip to an object and attempt to pull it across a flat surface, using the opposite end of your force meter. Measure the amount of extension of the pen tube from the body of the pen with a ruler. This will give you an idea of how much force is being required to drag each object. Record your results here: 4. Object __________

Surface __________

Length of extension __________

Answer Answers will vary but include: ½" 5. Object __________

Surface __________

Length of extension __________

Answer Answers will vary but include: 1"

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

6. Object __________

Surface __________

Length of extension __________

Answer Answers will vary but include: 2" 7. Why did some objects require more force than others did?

Answer Answers will vary but include: greater weight or friction 8. How does the surface used to slide across affect the CoF? Answer Answers will vary but include: the more friction the surface has, the more work it will take to move the object 9. If a liquid is placed between the two objects, what effect will that have on the CoF? Answer Answers will vary but include: it should be reduced 10. What could happen if the CoF of the brake pads or shoes is too high?

Answer Too much friction can cause the brakes to lock up easily, for the brakes to be very touchy to even slight application.

11. What could happen if the CoF of the brake pads or shoes is too low?

Answer Increased stopping distances, increased brake heat generation, glazing 12. What factors do you think are involved in determining the correct CoF for a particular vehicle?

Answer Answers will vary but may include weight, intended use, load capacity, brake design.

The CoF of brake linings have a large impact on how well a vehicle will stop. Using lining materials with too high or low a CoF can cause brake performance issues and rapid wear and can result in customer dissatisfaction. Similarly, the tires, because they are the contact between the vehicle and the road, also play an important role in brake operation. Even the best performing brakes will not stop a vehicle well if the tires cannot maintain proper traction.

Heat transfer is a very important factor for brake systems. The brake components—pads, shoes, rotors, and drums—can generate an enormous amount of heat. This heat must be

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 50: Brake Systems

dissipated quickly and efficiently, or it can cause damage to the brake components. Heat transferred to the brake fluid can, under the right (or wrong, depending on how you look at it) conditions, cause the fluid to boil. If the brake fluid boils, the gas, being compressible, will allow the brake pedal to sink to the floor. This condition, called brake fade, is very dangerous.

Once the brake fluid cools, it will condense back into a liquid state.

Obtain a large rubber band from your instructor. Measure the temperature of the rubber band or hold it against your forehead to feel its temperature. Now, rapidly stretch the rubber band and allow it to retract about a dozen times. Quickly remeasure its temperature.

13. What did the temperature of the rubber band do?

Answer Answers will vary but include: increase 14. Why did the rubber band respond this way?

Answer Answers will vary but include: friction of movement created heat 15. How quickly did the rubber band return to its original temperature?

Answer Answers will vary but include: one minute 16. What factors determine how quickly something will dissipate heat?

WARNING: Before test-driving any car, first check the fluid level in the master cylinder; depress the brake pedal to be sure that there is adequate pedal reserve; and make a series of low-speed stops to be sure the brakes are safe for road testing. Always make a preliminary inspection of the brake system in the shop before taking the vehicle on the road.

Answer Answers will vary but include: amount of heat, surface area, ambient temperature

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 51: DRUM BRAKES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 6 CONCEPT ACTIVITY 51-1 .......................................................................................................... 6 CONCEPT ACTIVITY 51-2.......................................................................................................... 9 CONCEPT ACTIVITY 51-3......................................................................................................... 10 CONCEPT ACTIVITY 51-4 ........................................................................................................ 11 CONCEPT ACTIVITY 51-5......................................................................................................... 12 CONCEPT ACTIVITY 51-6 ........................................................................................................ 15

SHORT ANSWER 1.

Name the two methods of attaching brake lining materials to the brake shoes.

Answer Linings are attached to brake shoes by riveting or bonding.

2. Explain how drum brakes create a self-multiplying brake force.

Answer The friction between the primary shoe and the brake drum forces the primary shoe to shift slightly in the direction that the drum is turning. The shifting of the primary shoe forces it against the bottom of the secondary shoe, which causes the secondary shoe to contact the drum. The secondary shoe is the one that is toward the rear of the vehicle. It comes into contact as a result of the movement and pressure from the primary shoe and wheel cylinder piston and increases the braking action.

3. List at least five separate types of wear and distortion to look for when inspecting brake drums.

Answer Worn or damaged drums may be scored, bell-mouthed, concave, convex, heat checked, cracked, out-of-round, threaded, or have hard spots.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

4. Explain the operation of an integral drum brake parking brake.

Answer When the parking brake pedal is applied, the cables and equalizer pull on the levers attached to the secondary shoe. The rear brakes with parking brake struts move the shoes against the brake drums. The shoes are held in position until the parking brake is released.

5. Explain how a duo-servo brake assembly works to provide great braking ability.

Answer In a duo-servo brake, the primary shoe has the position of the leading shoe in a nonservo brake. The ends of both shoes opposite the wheel cylinder and are not mounted on a rigid anchor attached to the backing plate as in a nonservo brake. The ends of the two shoes are linked to each other through the starwheel adjuster, and the ends of the shoes float in the drum. As the primary shoe is applied by the wheel cylinder, it develops self-energizing action as in a nonservo brake. Instead of being forced against an anchor, however, the primary shoe is forced against the secondary shoe and applies leverage to force the secondary shoe against the drum. This is servo action, or the action of mechanically multiplying force. The secondary shoe is then forced against the drum by the wheel cylinder force at one end and the servo action of the primary shoe at the other.

6. Explain how to check for brake drum out-of-round.

Answer Use a brake drum micrometer and check drum diameter twice, with the second measurement being perpendicular to the first. The difference between the two readings is the out-of-round measurement.

7. Explain the difference between machine-to and discard diameters.

Answer Answers will vary but may include: Machine to is typically .020"–.030" bigger than discard diameter to allow for wear on the drum.

8. List four items that should be checked when performing a drum brake inspection.

Answer Answers will vary but may include: The brake drum for wear and damage, the shoes, the wheel cylinder, the backing plate, the hardware and springs, the parking brake 9. Explain the purpose of the spring inside the wheel cylinder.

Answer Answers will vary but may include: The spring prevents the cups and pistons from retracting too far into the bore of the wheel cylinder.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

MULTIPLE CHOICE 1.

In a typical drum brake, which component provides a foundation for the brake shoes and associated hardware? a. Wheel cylinder b. Drum c. Backing plate d. Lining Answer: c. The backing plate is the foundation for the brake shoes and associated hardware.

2. Which of the following statements about drum brake shoes is not true? a. Linings may be riveted or bonded to the shoes. b. Shoe indentions hold the shoe in place against the backing plate. c. The shoe rim supports the shoe lining. d. The primary/leading shoe is typically the one that is positioned toward the front of the vehicle.

Answer: b. The shoe is held against the raised pads on the backing plate by the holddown springs.

3. Brake linings should be replaced when ___. a. linings are worn to within 1⁄32 inch of a rivet head b. linings are contaminated with oil or grease c. linings are contaminated with brake fluid d. all of the above Answer: d. All of the above 4. In the unapplied position, drum brake shoes are held against the anchor pin by the ___. a. holddown springs b. star wheel adjuster c. shoe holddown d. return springs Answer: d. In the unapplied position, drum brake shoes are held against the anchor pin by the return springs.

5. Duo-servo drum brakes are also known as what type of brake assembly? a. Leading-trailing brakes b. Self-energizing brakes c. Nonservo brakes d. None of the above Answer: b. Duo-servo brakes are also referred to as self-energizing.

6. On most vehicles, the automatic adjuster cables or levers are ___. a. installed on the secondary shoe b. set up to operate when the brakes are applied as the vehicle moves forward c. installed on the primary shoe d. set up to operate when the brakes are not applied Answer: a. The self-adjuster is usually installed on the secondary shoe.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

7. A buildup of brake dust and dirt between the lining and the drum is the most common cause of a ___. a. concave/barrel-shaped drum b. convex/tapered drum c. threaded drum surface d. scored drum surface Answer: d. A buildup of dust and dirt between the drum and the shoes can cause a scored drum.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that an out-of-round drum can cause a pulsating brake pedal.

Technician B says that an out-of-round drum can cause the brakes to grab. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. An out-of-round drum will push the shoes and wheel cylinder pistons back into their bores, causing a pedal pulsation. Grabbing can occur from the smaller diameter putting pressure against the shoes when the brakes are applied.

2. Technician A says that a grinding noise from a drum brake when it is not applied can be caused by a bad wheel bearing. Technician B says that a grinding noise from a drum brake when it is not applied can be caused by worn brake hardware. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A grinding noise coming from the area of the drum brake could be caused by a bad bearing or by worn, loose, or damaged hardware.

3. It has been determined that chatter and brake pull are being caused by hard spots on the brake drum: Technician A says that the problem can be solved by grinding off the hard spots. Technician B says that the drum must be replaced. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A drum with hard spots should be replaced. Grinding off the hard spots only removes the raised surface, and the hard spot will likely reappear when the drum gets hot again.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

4. Technician A says that the discard dimension of a brake drum is the drum’s allowable machining dimension. Technician B says that the discard dimension is the allowable wear dimension. There must be 0.030 inch left for wear after machining. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A drum should not be resurfaced to its discard dimension; leave about 0.030 inch (.762 mm) for wear.

5. After resurfacing a brake drum: Technician A cleans it using hot soapy water and a lint-free cloth. He then uses compressed air to thoroughly dry it. Technician B cleans the drum using a lint-free cloth dipped in a special brake cleaning solvent. She then allows the drum to dry before reinstallation. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Either soapy water or brake cleaner can be used after resurfacing a drum.

6. Drum linings are badly worn at their heel and toe: Technician A says that the problem is an out-of-round drum. Technician B says that the problem is a tapered drum. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. A tapered drum would cause wear on one side of the shoe.

7. When machining brake drums: Technician A tries to remove only enough metal to obtain a true, smooth surface. Technician B cuts the drum on the other side of the axle to the same diameter as the one that was cut first. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. Only enough material to true the drum should be removed and both drums should be similar in diameter for even wear.

8. While discussing what would happen if too much metal is removed from a drum by machining: Technician A says that noise can result from the thin drum vibrating when the brakes are applied. Technician B says that the brakes could fade because the thin drum is unable to absorb heat during braking. Who is correct? a. Technician A only b. Technician B only

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. friction surface is too thin.

Both noise and fade can occur if the drum

9. Technician A checks the surface of the drum for scoring by running a fingernail across the surface. Technician B replaces any drum that is scored. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Some scoring on a drum can be cleaned up with a brake lathe.

10. While discussing pull during braking: Technician A says that this can be caused by one tire being underinflated. Technician B says that a frozen wheel cylinder on one side of the car can cause this. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. Low tire pressure can cause a vehicle to pull to the side with low pressure during braking as load increases on the tires. A wheel cylinder that is frozen will not apply the brake, causing a pull to the side that is applying.

TECH MANUAL CONCEPT ACTIVITY 51-1 Tire Construction

FIGURE 51–1 Typical duo-servo drum brake.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

1.

Identify the components of the duo-servo brake shown in Figure 51-1. a. __________ Answer Secondary shoe return spring b. __________ Answer Wheel cylinder c. __________ Answer Anchor d. __________ Answer Primary shoe return spring e. __________ Answer Backing plate f.

__________

Answer Primary shoe g.

__________

Answer Connecting/self-adjuster spring h. __________ Answer Self-adjuster i.

__________

Answer Secondary shoe

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

j.

__________

Answer Hold down spring Duo-servo drum brakes operate by using leverage, hydraulics, and friction to slow the rotation of the brake drum. See Concept Activities 50-1, 50-2, and 50-3 to review these principles. In a duo-serve brake system, when the brake pedal is pressed, brake fluid under pressure pushes equally on the two pistons of the wheel cylinder. The pistons in the wheel cylinder push against the brake shoes, forcing them against the inside surface of the brake drum. Once the primary shoe contacts the drum, it attempts to rotate in the same direction as the drum. This reaction force is transferred to the secondary shoe through the self-adjuster. This action increases the braking force created by the hydraulic system alone (Figure 51-2).

FIGURE 51–2 Duo-servo action drum brake operation. (A) The primary shoe is forced against the drum, causing the shoe to rotate slightly with the drum; (B) The primary shoe pushes against the secondary shoes through the self-adjuster; (C) The secondary shoe applies against the drum with increased force.

2. What types of vehicles would benefit by using duo-servo brakes?

Answer Larger vehicles, trucks, vans

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

3. What types of vehicles would not require duo-servo brakes?

Answer Smaller FWD vehicles

CONCEPT ACTIVITY 51-2 Tire Construction

FIGURE 51–3 Typical non-servo drum brake.

1.

Identify the components of the non-servo drum brake shown in Figure 51-3. a. __________ Answer Leading shoe b. __________ Answer Wheel cylinder c. __________ Answer Hold down spring d. __________ Answer Trailing shoe e. __________ Answer Anchor

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

f.

__________

Answer Return/retaining spring g.

__________

Answer Backing plate h. __________ Answer Self-adjuster 2. Where would you expect most of the wear to occur on a non-servo drum brake design?

Answer Answers will vary but include: the top half of both shoes 3. Explain three differences in the design and layout of non-servo brakes compared to duo-servo brakes.

Answer Answers will vary but include: the main difference is the location of the anchor and non-servo brakes do not increase application force when applied.

CONCEPT ACTIVITY 51-3 Parking Brake 1.

On what components is proper drum parking brake operation dependent?

Answer Shoes, drum, parking brake equalization bar/strut, self-adjuster

2. Explain two possible causes for excessive parking brake pedal or hand-control travel.

Answer Misadjusted shoe-to-drum clearance, misadjusted parking brake 3. What should you check before adjusting the parking brake?

Answer Shoe-to-drum clearance

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

CONCEPT ACTIVITY 51-4 Drum Micrometer To measure a brake drum, you must understand how to set up and read a drum micrometer.

Figure 51-4 shows the parts of a drum micrometer. Both anvils can move over the graduated shaft on the micrometer when the lock screws are loosened. The shaft on an English micrometer is graduated in inches and in 1/8s (0.125) of an inch. The dial reads from 0 to 0.130 inch (Figure 51-5).

FIGURE 51–4 Parts of a drum micrometer.

FIGURE 51–5 The scales on an English micrometer.

If the two anvils are placed on the 9/10 mark on the left and the 9/8 mark on the right, the micrometer will be reading exactly 9 inches when the plunger of the dial is pressed in and the needle is pointing at 0 (Figure 51-6).

FIGURE 51–6 An example of a drum measurement.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

CONCEPT ACTIVITY 51-5 Drum Micrometer Reading, English Practice reading an English drum micrometer by completing the activity below (Figure 51-7).

Micrometer reading __________ Answer 9.040"

Micrometer reading __________ Answer 9. 270"

Micrometer reading __________ Answer 8.685

Micrometer reading __________ Answer 8.630 FIGURE 51–7 Practice drum micrometer reading.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

To measure a brake drum, first set the micrometer to the drum’s nominal size (Figure 51-8).

Move the micrometer back and forth until the largest reading is obtained. In this example, the micrometer is set to 11.375 inches (Figure 51-9). When the micrometer is placed into the drum and the plunger on the dial extends, the drum is larger than 11.375 inches (Figure 51-10).

Because the plunger extended out until the dial read 0.015 inch, this amount is added to the 11.375 inches for a total of 11.390 inches. To check for out-of-round, turn the micrometer perpendicular to the first measurement and remeasure. The two readings should be identical.

If they are not the same, the drum is out-of-round.

FIGURE 51–8 A drum micrometer is used to measure the inside diameter of a brake drum.

FIGURE 51–9 Begin drum measurement by setting the micrometer to the nominal drum diameter.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

FIGURE 51–10 Add the dial indicator reading to the original micrometer setting to get the drum diameter.

Reading a metric micrometer is similar to reading an English micrometer, except the units are centimeters instead of inches. Figure 51-11 shows an example of how to read a metric micrometer.

FIGURE 51–11 How to read a metric drum micrometer.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 51: Drum Brakes

CONCEPT ACTIVITY 51-6 Drum Micrometer Reading, English Practice reading an English drum micrometer by completing the activity below (Figure 51-12).

Micrometer reading __________ Answer 27.23 cm or 272.3 mm

Micrometer reading __________ Answer 23.45 cm or 234.5 mm

Micrometer reading __________ Answer 21.75 cm or 217.5 mm

Micrometer reading __________ Answer 24.88 cm or 248.8 mm FIGURE 51–12 Practice reading metric drum micrometer readings.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 52: DISC BRAKES

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 4 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 52-1 ......................................................................................................... 7 CONCEPT ACTIVITY 52-2 ......................................................................................................... 9 CONCEPT ACTIVITY 52-3 ........................................................................................................ 10 CONCEPT ACTIVITY 52-4 ........................................................................................................ 10 CONCEPT ACTIVITY 52-5 ........................................................................................................ 16

SHORT ANSWER 1.

List three advantages of disc brakes.

Answer Answers will vary but may include: More resistant to fade, less prone to pulling, and they automatically self-adjust.

2. Why do disc brake systems require greater application force compared to drum brakes?

Answer Answers will vary but may include: The surface area of the brake pad is much smaller than that of brake shoes.

3. Explain how to test rotor runout.

Answer Answers will vary but may include: Mount a dial indicator so that the plunger is against the rotor surface. Spin the rotor and measure the movement of the dial indicator needle.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

4. Name the three major assemblies that make up a disc brake.

Answer The three major assemblies that make up a disc brake are (1) hub and rotor, (2) caliper, and (3) brake pads.

5. Name the three types of calipers used on disc brakes.

Answer The three types of calipers used are fixed, sliding, and floating designs.

6. Describe the differences between floating and fixed rotors.

Answer Floating rotors are able to slide on the hub. Fixed rotors are held in placed by wheel bearings and require the bearings to be disassembled to remove the rotor.

7. What is the difference between floating and sliding calipers?

Answer A floating caliper is mounted to its support on two locating pins, or guide pins, that are threaded into the caliper support. The caliper slides on the pin in a sleeve or bushing.

The pins let the caliper move in and out and provide some flexibility for lateral movement to help the caliper stay aligned with the rotor. The pads are attached to the piston on the inboard side and to the caliper housing on the outboard side. The caliper support for sliding calipers has two V-shaped surfaces that are called abutments, or ways. The caliper housing has two matching machined surfaces. The caliper slides onto the caliper support, where the two parts are held together with a caliper support spring, a key, and key retaining screw. An anti-rattle spring is used to prevent noise from vibration.

8. What is rotor parallelism and how is it checked?

Answer Rotor parallelism refers to thickness variations in the rotor from one measurement point to another around the rotor surface. The thickness of the rotor is measured at about eight points, equidistant (45 degrees) around the surface of the rotor.

9. Why is brake fluid removed from the master cylinder prior to working on disc brakes?

Answer Removing brake fluid from the master cylinder is an important preliminary step for all disc brake service. If you forget to remove fluid, it may overflow the reservoir and spill when the caliper pistons are pushed back into the caliper bores for caliper or pad removal.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

10. Describe the procedure for using compressed air to remove a piston from a brake caliper.

Answer Procedure for using compressed air to remove a piston from a brake caliper: 1) Remove the caliper from the car and clamp it securely in a bench vise by one of its mounting points.

2) Place a wooden block, wrapped in shop cloths, in the caliper opening. The block should be thin enough to let the piston move outward in its bore, but thick enough to keep the piston from leaving the bore completely.

3) Cover the caliper with cloths as necessary to keep brake fluid from spraying during removal.

4) Insert an air nozzle with a rubber tip into the brake hose port and gradually apply air pressure. Keep your fingers away from the piston.

5) If an OSHA-approved safety nozzle that limits nozzle air pressure to 30 psi is available, use it as first choice to remove the piston.

6) If an OSHA-approved nozzle is not available but you can regulate the air pressure, start with about 30 psi and gradually increase line pressure. Use the lowest possible air pressure to loosen the piston. If you cannot regulate line pressure, apply air in short increments. Do not exceed normal maximum shop pressure of 90 to 100 psi.

7) When the piston pops free, remove the air nozzle and the wooden block and extract the piston the rest of the way by hand.

11. List three conditions that dictate that a rotor should be refinished.

Answer Brake rotors should be refinished only when they have minor imperfections, fail a lateral runout check, have excessive thickness variations, when there is noticeable brake pulsation, and when there are heat spots or excessive scoring that can be removed by resurfacing. However, a rotor should not be refinished if it is too thin or will be too thin after machining; regardless of the reason it needs turned.

12. Give two main advantages of an on-vehicle lathe versus a bench lathe.

Answer One advantage of an on-vehicle lathe is that the rotor does not have to be removed from the spindle or the hub, thereby saving time and labor. Another advantage is they are ideal for rotors with excessive runout problems. Shoe and applies leverage to force the secondary shoe against the drum. This is servo action, or the action of mechanically multiplying force. The secondary shoe is then forced against the drum by the wheel cylinder force at one end and the servo action of the primary shoe at the other.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

13. What should be done to remove rust, corrosion, pitting, and scratches from the piston bore?

Answer Light scratches and corrosion may be removed by cleaning with crocus cloth; the cylinder may also be honed if the manufacturer recommends it. Deep scratches or pitting usually mean the caliper should be replaced.

14. What type of brake uses the inside of each rear-wheel hub and rotor assembly as a parking brake drum?

Answer A rear disc/drum auxiliary parking brake, also called a drum-in-hat parking brake, uses the inside of the hub and rotor as a parking brake.

MULTIPLE CHOICE 1.

Which term refers to variations in thickness of the rotor? a. Torque b. Lateral runout c. Parallelism d. Pedal pulsation Answer: c. Variation in rotor thickness is referred to as parallelism.

2. Which of the following is not likely to cause a pulsating brake pedal? a. Loose wheel bearings b. Worn brake pad linings c. Excessive lateral runout d. Nonparallel rotors Answer: c. Worn brake pads are more likely to cause noise, not a pulsating brake pedal.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a hard brake pedal on a vehicle with disc brakes can be caused by air in the hydraulic system. Technician B says that a pulsating pedal on a vehicle with disc brakes can be caused by a restricted brake line. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Air in the hydraulic system would cause a spongy, not a hard, pedal. A pulsating brake pedal is most likely caused by a warped rotor, not a restricted brake line.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

2. When replacing brake pads on a vehicle: Technician A works on one wheel before beginning work on another. Technician B uses a minimum of 52 psi of air pressure to force the piston from the caliper housing. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: A Technician A is correct. It is generally a good idea to only take on brake assembly apart at a time so the assembled side can be used as a reference if needed.

Air pressure should be limited to 30 psi for caliper disassembly.

3. When examining disc brakes: Technician A visually inspects the rotor and says that the rotor can be reused if it is not damaged or scored. Technician B says that it is normal for the inboard pad to be slightly more worn than the outside pad. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. A visual examination of rotors is insufficient.

They should be measured for runout, parallelism, and minimum thickness before they are reused. It is not considered normal for the inboard pad to wear faster than the outboard pad. Uneven wear often means the caliper is sticking and not giving equal pressure to both pads.

4. When reassembling an overhauled brake caliper: Technician A cleans brake components in denatured alcohol. Technician B cleans brake components in clean brake fluid. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Both procedures are recommended by various manufacturers.

5. While discussing how to remove the piston from a brake caliper: Technician A says that the dust boot should be removed, then a large dull screwdriver should be inserted into the piston groove to pry the piston out. Technician B says that air pressure should be injected into the bleeder screw’s bore to force the piston out of the caliper. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: d. Neither technician is correct. Never try to pry the piston out using a screwdriver. Air pressure may be used to force the piston out of the bore, but it is supplied to the fluid inlet, not through the bleeder screw bore. An attempt to supply air pressure through the bleeder bore would necessitate blocking the fluid inlet passage. It is easier to close the bleeder screw and apply air at the inlet passage. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

6. The functions of a splash shield are being discussed: Technician A says that disc brakes will function normally without a splash shield in place. Technician B says that a splash shield helps to direct cooling air over the rotor. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct The brakes will operate normally but air flow may be disturbed, reducing cooling.

7. Technician A says that the piston seal retracts the caliper piston when hydraulic pressure is released. Technician B says that a return spring is used to retract a caliper piston. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Calipers do not have return springs.

8. Technician A says that fixed calipers use a piston on each side of the rotor to apply the brakes. Technician B says that sliding calipers typically use only one piston or pistons on one side of the rotor. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Fixed calipers use at least one piston against each pad to operate. Sliding calipers typically only use one piston against the inboard pad.

9. While installing new brake pads: Technician A coats the caliper bushings with silicone grease before installing the mounting bolts and sleeves of floating calipers. Technician B lubricates the caliper ways on the caliper support and the mating parts of the sliding caliper housings with the recommended lubricant. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Lubrication of the bushings and sleeves as well as the points on the caliper are common.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

10. Loaded calipers are being discussed: Technician A says that loaded calipers are replacement calipers that come with pads and hardware already installed. Technician B says that loaded calipers should always be installed in axle sets. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Loaded calipers contain the pads and all related parts and should be installed in pairs.

TECH MANUAL CONCEPT ACTIVITY 52-1 Disc Brakes

Figure 52–1 Identify the disc brake components.

1.

Identify the components of the disc brake system shown in Figure 52-1. a. __________ Answer Outboard pad b. __________ Answer Inboard pad

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

c. __________ Answer Bleeder screw d. __________ Answer Piston seal e. __________ Answer Mounting bolt f.

__________

Answer Mounting bracket g.

__________

Answer Dust boot h. __________ Answer Rotor i.

__________

Answer Caliper body j.

__________

Answer Piston 2. Which component allows for the self-adjusting capability of disc brakes?

Answer Piston seal

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

3. Describe the three types of caliper designs.

Answer Answers will vary but should include sliding, floating, or fixed.

CONCEPT ACTIVITY 52-2 Calipers 1.

Examine a disc brake assembly and note how the caliper is attached to the steering knuckle.

Is this a floating, sliding, or fixed caliper design?

Answer Answers will vary but include: floating, sliding, or fixed

2. How does the caliper mounting allow for back-and-forth movement?

Answer Answers will vary but include: it moves on pins or bushings 3. Remove the caliper mounting bolts. Describe how the mounting bolts allow for caliper movement.

Answer Answers will vary but include: the caliper is able to slide over the bushings in their bores 4. Examine the mounting bolt sleeves, bushings, O-rings, and other related hardware.

Note your findings.

Answer Answers will vary but include: good or not good 5. What type of problems could cause the caliper not to move back and forth correctly?

If this is a fixed caliper, what could cause uneven pad wear?

Answer Answers will vary but include: uneven pad wear, binding pads in caliper 6. What type of wear or symptoms could this cause?

Answer Answers will vary but include: uneven pad wear, noise

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

CONCEPT ACTIVITY 52-3 Disc Brake Design 1.

In addition to heat dissipation, how does the design of disc brakes reduce brake fade?

Answer As the pads and rotor get hot they get closer together, unlike with drum brakes.

2. Explain why disc brakes require greater application force than drum brakes.

Answer no self-energizing action 3. Explain why some brake rotors are drilled and/or slotted.

Answer To allow water and gas to dissipate off the rotor more quickly

CONCEPT ACTIVITY 52-4 Rotor Micrometer Reading 1.

Why does a rotor micrometer use a pointed anvil compared to a flat anvil on a standard micrometer?

Answer To get into any grooves present in the rotor

Brake rotor micrometers are read the same way as standard micrometers. Figure 52-2 shows how to read a standard English micrometer. Practice your micrometer reading skills by completing the following readings (Figure 52-3).

FIGURE 52–2 A micrometer is read by totaling the number of whole divisions on the barrel scale and adding the thousandths from the thimble scale. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

Answer .607”

Answer 1. 090

Answer 1.216

Answer 1. 027

Answer 1.242 FIGURE 52–3 Practice reading a disc brake micrometer.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

Metric brake micrometers are read as a traditional metric micrometer. Figure 52-4 shows how to read a metric micrometer. Practice your metric micrometer reading skills by completing the following readings (Figure 52-5).

FIGURE 52–4 The metric micrometer is read similar to the standard micrometer. The graduations are now read in millimeters rather than inches.

Answer 18.17 mm

Answer 10.41 mm

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

Answer 28.22 mm FIGURE 52–5 Determine the metric micrometer readings.

Brake rotors normally have two thickness specifications, minimum thickness and machine-to.

The machine-to, also called minimum refinish thickness, is typically 0.020–0.030 inch (0.51– 0.76 mm) larger than minimum thickness.

2. Why is there a difference between machine-to and the minimum thickness specifications?

Answer Answers will vary.

Vibration, also called pulsation, from the disc brakes is felt in the brake pedal and steering wheel during brake application. The pulsations can range from very slight to severe depending on the cause and the condition of the brake components. The major cause of disc brake pulsation is brake rotor thickness variation, also called disc brake taper or rotor parallelism.

Rotors must also be checked for thickness variation. Figure 52-6 illustrates how to check for thickness variation. Subtract the smallest reading from the largest to obtain the actual variation. Many manufacturers specify a very small allowable thickness variation, usually around 0.0005 inch (0.0127 mm). To measure this, you will need a micrometer that reads to one ten-thousandths of an inch or millimeter. Figure 52-7 is an example of a micrometer with an additional scale, called a Vernier scale, used to measure up to 0.0001 inch (0.00254 mm).

FIGURE 52–6 Check for thickness variations by measuring at eight to twelve points around the rotor.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

FIGURE 52–7 The Vernier scale indicates 0.0002".

3. Determine the total reading of this micrometer (Figure 52-8).

FIGURE 52–8 Determining the micrometer reading shown.

Micrometer reading __________ Answer

0.2508 mm

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

The final rotor measurement is to check for lateral runout. Mount a dial indicator as shown in Figure 52-9. Secure the rotor with lug nuts and slowly rotate the rotor while watching the dial indicator. Runout specifications vary with manufacturer, but generally, less than 0.003 inch (2.0762 mm) is considered acceptable.

FIGURE 52–9 Measuring rotor lateral runout.

4. If a runout reading is obtained that is beyond the specification, what diagnostic steps should be taken next?

Answer Determine if the rotor, hub, or bearing is the cause 5. What other components can cause the rotor to show excessive runout?

Answer The hub and bearing 6. If the rotor has excessive runout, how can it be corrected?

Answer On-car lathe or replacement Rotors, like brake drums, are inspected for scoring, cracks, hard spots, and glazing (Figure 5210). Light scoring is acceptable and may not require refinishing. Inspect the cooling fin area.

Excessive rusting of the cooling fins can cause poor heat dissipation and rotor failure.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

FIGURE 52–10 Typical rotor defects.

7. What can cause scoring of the brake rotor surfaces?

Answer Excessive pad wear 8. What can cause brake glazing?

Answer Incorrect pad application (incorrect coefficient of friction), brake overheating, driving habits

CONCEPT ACTIVITY 52-5 Disc Brake Noise Diagnosis Disc brake noise is common and sometimes difficult to correct. Verify during a test drive that the noise is brake related. Many vehicles use audible pad wear indicators, which are designed to emit a loud noise when the pads are worn down to the point of replacement. The vibrations of the brake pads and pad hardware cause brake pad squeal. Many manufacturers use special shims and springs to reduce pad squeal or change the frequency so that it is inaudible to human hearing. Figure 52-11 and Figure 52-12 show two examples of brake hardware designed to reduce noise.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 52: Disc Brakes

FIGURE 52–11 Brake pad and anti-rattle spring.

FIGURE 52–12 Brake pad shims.

1.

Examine several different disc brake assemblies and note the use of shims and springs to reduce pad noise. Summarize your findings.

Answer Answers will vary but include: some pads use shims, some do not, some pads use retaining clips, and some do not.

2. As the pads and hardware age, how can the effects of wear and climate affect their operation?

Answer Answers will vary but include: pads can rust, deteriorate, become stuck, and wear unevenly

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 53: ANTILOCK BRAKE, TRACTION CONTROL, AND STABILITY CONTROL SYSTEMS

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 4 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 53-1 ......................................................................................................... 7 CONCEPT ACTIVITY 53-2 ......................................................................................................... 8 CONCEPT ACTIVITY 53-3 ......................................................................................................... 8

SHORT ANSWER 1.

What is the primary difference between an automatic traction control system and a stability control system?

Answer Automatic traction control is a system that applies the brakes of a drive wheel when it attempts to spin and lose traction. Automatic stability control systems correct oversteer and understeer by applying one wheel brake to bring the vehicle back under control.

2. Briefly describe the proper steps and testing needed to accurately diagnose antilock braking systems.

Answer Diagnosis and testing of an ABS include (1) prediagnostic inspections and a test drive, (2) a warning light and symptom troubleshooting, (3) on-board self-diagnostics and code retrieval, and (4) individual component testing and trouble-code-based troubleshooting.

3. An ABS modulates brake pressure. What does this mean?

Answer Pressure modulation means that the system rapidly applies and releases hydraulic pressure at the wheels to prevent wheel locking.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

4. Explain the difference between oversteer and understeer.

Answer Understeer is a condition in which the vehicle is slow to respond to steering changes, such as when a vehicle fails to successfully negotiate a corner. Oversteer is the opposite condition; it occurs when the rear wheels try to swing around or fishtail with possible loss of control.

5. List the various methods used by traction control systems to eliminate wheel spin.

Answer Wheel spin may be controlled by retarding ignition timing, reducing or cutting off fuel injection pulses to one or more cylinders, increasing exhaust gas re-circulation (EGR) flow, momentarily upshifting the transmission to a higher gear, and applying the brakes at the driving wheels.

6. Explain how the ABS system determines wheel lockup.

Answer Answers will vary but may include: The EBCM monitors wheel speed data from the wheel speed sensors. If a sensor shows much fewer signals compared to the others, the EBCM reads it as wheel lockup.

7. Describe how to depressurize an integral ABS system.

Answer Answers will vary but may include: Press the brake pedal 40–50 times.

8. Explain two ways to test an AC generating wheel-speed sensor.

Answer Answers will vary but may include: Use a DMM or scope to measure AC volts, Connect the leads and spin the wheel to produce a signal. Compare the reading to specifications or to other sensors for comparison.

9. Describe what actions the stability control system can take to reduce wheel slip.

Answer Answers will vary but may include: The PCM may upshift the transmission and reduce engine torque and speed.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

10. What are the functions of an isolation/dump valve?

Answer During normal braking, pressure will pass through the valve assembly. The ECM receives a signal from the brake switch when brakes are applied and begins to monitor the VSS signal at speeds over 5 MPH. If the control module detects a deceleration rate from the VSS that would indicate probable rear wheel lock-up, it will activate the isolation valve, which will stop the buildup of pressure to the rear wheels. If further deceleration occurs that would indicate lock-up, the control module will rapidly pulse the dump valve to release brake pressure into the accumulator. The control module will continue to pulse the dump valve until rear wheel deceleration matches the vehicle’s deceleration rate or the desired slip rate. When wheel speed picks up, the control module will turn off the isolation valve, allowing the fluid in the accumulator to return to the master cylinder and normal braking control to resume.

11. Describe the normal pedal feel when the ABS is activated during hard braking.

Answer During ABS controlled braking, there should be a slight pulsation of the brake pedal.

12. Define the difference between an integrated and a nonintegrated antilock braking system.

Answer An integrated system combines all of the components, such as the master cylinder, brake booster, and ABS hydraulic unit that are necessary to provide conventional hydraulic brakes, power assist, and antilock control into one assembly. With a nonintegral system, the functions of conventional braking and power assist are provided by the conventional power brake components (a separate master cylinder, brake booster, and ABS hydraulic unit) while the function of antilock control is provided by the ABS. It may be considered an add-on system.

13. Why are the wires leading to some wheel-speed sensors twisted?

Answer Wheel speed sensors are PM generators which have AC voltage outputs. Radio signals are also AC-modulated signals, therefore the signal produced by PM generators can be affected by radio frequency interference (RFI). The wires to and from a PM generator must be shielded from other wires in the vehicle, that radiate electromagnetic interference (EMI). Since the suspension must be able to move as the vehicle travels, the electrical wiring to the wheel speed sensors cannot be shielded in conduit. Instead the wires are twisted at least one turn for every 1.75-inch.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

14. Describe the differences between passive and active wheel-speed sensors.

Answer Passive wheel speed sensors are typically two-wire permanent magnet analog AC voltage generating sensors. As a tooth on the reluctor wheel passes the sensor, a positive AC voltage is produced. As the tooth passes by the sensor, a negative AC voltage is produces. Active sensors produce DC digital square wave signals and are typically Hall-effect sensors. Active sensors can read both forward and rearward rotation and monitor wheel speeds more accurately at low speeds.

MULTIPLE CHOICE 1.

Which of the following is a true statement? a. In some antilock brake systems, the power brake assist is provided by pressurized brake fluid supplied by the hydraulic accumulator. b. The accumulator is a small, sealed chamber mounted to the pump/motor assembly. c. The accumulator holds a highly pressurized nitrogen gas that is used to generate a charging pressure. d. All of the statements are true.

Answer: d. All of the statements are true. Accumulators are often nitrogen charged

and used to provide pressure for the power assist.

2. What is the name for the gas-filled pressure chamber that is part of the antilock braking system’s pump and motor assembly? a. Control module b. Accumulator c. Sensor d. Reservoir Answer: b. The accumulator is a gas-filled pressure chamber attached to the pump and motor assembly.

3. When inspecting wheel-speed sensors, check for all of the following except ___. a. buildup of metal or rust on the sensor b. proper contact between the pole piece and tone ring c. secure sensor mounting d. condition of the tone ring teeth Answer: b. There should be a small air gap between the pole piece and tone ring.

4. Which type of ABS is not commonly used on modern vehicles? a. Four-wheel nonintegral b. Two-wheel nonintegral c. Four-wheel integral d. None of the above Answer: b. Two-wheel nonintegral systems were replaced by four-wheel systems.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a malfunction of the ABS causes the control module to shut off or inhibit the system. Technician B says that a loss of hydraulic fluid or power booster pressure disables the antilock brake system. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. A system fault or loss of pressure will disable the antilock capabilities of the system.

2. While road testing a car equipped with an ABS: Technician A says that during heavy braking, several pulses may be felt through the brake pedal. Technician B says that a spongy pedal during normal braking is normal. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. During heavy braking the ABS is modulating pressure, and pulsations felt at the brake pedal are normal. A spongy pedal is a symptom of air in the system and is not considered normal.

3. Technician A says that the accumulator in an ABS is used to store hydraulic fluid to provide residual pressure for power-assist braking. Technician B says that the booster pump in an antilock system provides pressurized hydraulic fluid for the ABS. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. The accumulator pressure can supply several power-assisted stops if the boost pump stops working.

4. Technician A says that it is normal for the amber brake lamp to light when the ABS is activated during braking. Technician B says that it is normal for the red brake lamp to be on whenever the ignition is on and the engine is off. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Both amber and red brake warning lights are on with the ignition on and the engine not running. The amber brake light is illuminated with the engine running if the ABS module senses a defect in the ABS.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

5. Technician A says that some antilock brake systems use a lateral acceleration sensor in addition to the wheel-speed sensors. Technician B says that traction control systems apply one wheel brake to get the vehicle going in the direction in which it is being steered. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Some systems use a lateral acceleration sensor in addition to the wheelspeed sensors. Traction control applies one wheel when it attempts to spin and lose traction; stability control applies one brake to keep the vehicle going in the direction in which it is being steered.

6. Technician A says that wheel-speed sensors send an AC voltage signal to the control module. Technician B says that wheel speed signals create an AC signal voltage by altering a reference voltage received from the control module. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. The wheel speed sensor is a voltage generating sensor and not a reference voltage sensor.

7. A vehicle’s ABS activates during low speed turns on dry pavement. Technician A says a loose wheel bearing may cause this. Technician B says this is normal because wheel speed sensors are not accurate at very low speeds. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. A faulty or loose wheel bearing can cause unwanted ABS activation, often during low-speed driving conditions.

8. Technician A says that each ABS has its own diagnostic procedure involving use of the brake and antilock warning lamps, special testers, troubleshooting charts, and wiring diagrams. Technician B says that ABS codes are lost from memory when the ignition is turned off. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Each manufacturer has its own diagnostic approach to determine the cause of ABS concerns. Modern systems are able to retain codes when the key is turned off.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

9. Technician A says engine power may be reduced if positive wheel spin is detected by the ABS/ATC system. Technician B says positive wheel spin indicates a wheel is locked up. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Positive wheel spin means that a drive wheel has lost traction. Technician A is correct because the system may reduce engine power to stop the wheel from spinning.

10. Technician A says that some traction control systems eliminate wheel spin by applying the brakes on the driving wheels. Technician B says that some traction control systems eliminate wheel spin by retarding ignition timing and cut-ting off fuel injection. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Wheel spin can be managed using several methods, including reducing engine power, upshifting the transmission, and applying the service brakes.

TECH MANUAL CONCEPT ACTIVITY 53-1 Identify ABS/ATC/ESC Function Match the vehicle condition to the correct control system, antilock brakes (ABS), automatic traction control (ATC), or electronic stability control (ESC). a. Monitor wheel speeds Answer ABS, ATC, ESC b. Control wheel lockup Answer ABS c. Prevent wheel spin Answer ATC

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

d. Reduce body roll Answer ESC e. Monitor steering input Answer ESC f.

Monitor throttle position Answer ATC, ESC

CONCEPT ACTIVITY 53-2 Identify High-Pressure ABS Accumulators ABS/ATC systems that use accumulators operate at very high pressures. Use caution whenever servicing these systems.

1.

How can a system with high-pressure accumulators be identified?

Answer Warning labels or tags

2. How can the pressure in the accumulators be relieved?

Answer Answers will vary but may include pumping the brake pedal up to 40 times.

CONCEPT ACTIVITY 53-3 Identify ABS/ATC/ESC Warning Lights 1.

Low brake fluid level can cause which instrument panel (IP) warning light(s) to turn on?

Answer Answers will vary but include: ABS, brake, TC, ESC, stability control

2. If there is a leak in the brake hydraulic system, which IP warning light(s) may illuminate?

Answer Answers will vary but include: ABS, brake, TC, ESC, stability control

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 53: Antilock Brake, Traction Control, and Stability Control Systems

3. List the nonbrake system components that can affect the operation of the brake, ABS, ATC, or ESC systems.

Answer Answers will vary but include: tire condition, ride height sensors, yaw sensors, steering angle sensor 4. How can excessive rust buildup around the wheel-speed sensor (WSS) cause ABS/ATC malfunctions?

Answer Answers will vary but include: Rust can damage the sensor or reduce the strength of the signal.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 54: HEATING AND AIR CONDITIONING

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 4 Tech Manual ........................................................................................................................ 7 CONCEPT ACTIVITY 54-1 ......................................................................................................... 7 CONCEPT ACTIVITY 54-2 ......................................................................................................... 7 CONCEPT ACTIVITY 54-3 ......................................................................................................... 8 CONCEPT ACTIVITY 54-4......................................................................................................... 9

SHORT ANSWER 1.

What is the amount of heat necessary to change the state of a substance called?

Answer The amount of heat necessary to change the state of a substance is called its latent heat.

2. Explain how an electromagnetic compressor clutch operates.

Answer The clutch contains a large coil of wire, which when supplied power and ground, becomes energized. This creates a strong magnetic field that is used to engage the compressor clutch and lock it to the driveshaft.

3. Describe four ways in which the heater control valve may be controlled.

Answer Current heater control valves may be controlled by: a cable, vacuum, a stepper motor (electronically), or by a thermostat.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

4. What is the purpose of the compressor clutch thermostatic switch?

Answer A compressor clutch thermostatic switch senses the evaporator’s outlet air temperature through a capillary tube that is part of the switch assembly. With a high sensing temperature, the thermostatic switch is closed and the compressor clutch is energized. As the evaporator outlet temperature drops to a preset level, the thermostatic switch opens the circuit to the compressor clutch. The compressor then ceases to operate until such time as the evaporator temperature rises above the switch setting.

5. What does “change of state” mean? And why is it important to air-conditioning units?

Answer Objects can be in one of three forms: solid, liquid, or gas. Change of state means that the object changes from one state to another with the consumption or release of large amounts of energy. Large amounts of temperature may be transferred by an air conditioning system in this manner.

6. What state is the refrigerant in when it leaves the condenser?

Answer Refrigerant leaves the condenser as a warm-temperature, high-pressure liquid.

7. What causes condensed water to leak from the air-conditioning system?

Answer Humidity from the air condenses on the evaporator surface while the air-conditioner is running. When the air-conditioner is shut off, this moisture drips from the evaporator case similar to a defrosting refrigerator.

8. Explain why a diode may be wired into the compressor clutch circuit.

Answer A diode may be wired into the compressor clutch circuit to suppress or clamp the voltage spike that occurs when the magnetic field in the clutch coil collapses when the clutch is turned off.

9. Describe the basic refrigerant cycle.

Answer Answers will vary but may include: Refrigerant leaves the compressor and is cooled in the condenser, from there it passes through a metering device where its temperature and pressure decrease. It passes through the evaporator where it picks up heat and turns from a liquid to a gas. It leaves the evaporator and is drawn into the compressor.

It leaves the compressor as a high temperature high pressure gas.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

10. Explain why special refrigerant oil is required with electrically driven A/C compressors.

Answer Answers will vary but may include: The oil must be non-conductive with the electric motors used in the compressors.

11. List five components of the ventilation system.

Answer Answers will vary but may include: the vents, fan, cabin filter, the control head, air inlet

MULTIPLE CHOICE 1.

On which of the following laws of nature is the air-conditioning system based? a. Heat flow b. Heat absorption c. Pressure and boiling points d. All of the above Answer: d. All of the above. Air conditioning systems operate by managing the

pressure and temperature of the refrigerant.

2. Which of the following statements is true? a. Refrigerant leaves the compressor as a high-pressure, high-temperature liquid. b. Refrigerant leaves the condenser as a low- pressure, low-temperature liquid. c. Refrigerant returns to the compressor as a low-pressure, high-temperature vapor. d. None of the above.

Answer: d. None of the above is true. Refrigerant leaves the compressor as a high pressure, high temperature gas and leaves the condenser as a high temperature liquid.

3. Which of the following statements is false? a. The condenser is normally mounted just behind the radiator. b. The receiver/dryer is a storage tank for the liquid refrigerant from the condenser. c. An accumulator is not used in a system with a receiver/dryer. d. All of the above.

Answer: c. Accumulators are not commonly used with receiver/dryers.

4. Which of the following statements about PTC heaters is not true? a. Some vehicles have a PTC heating element in the heater core. b. Some vehicles have a PTC element installed in an air duct from the blower housing to increase the air temperature in the ducts. c. PTC heaters are electronically controlled and work with the cooling system to provide hot coolant. d. PTC elements are small ceramic stones that react quickly to changes in current. © 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

Answer: c. PTC heaters are electronically controlled and work independently of the cooling system.

5. Which of the following is electrically connected in series with the compressor electromagnetic clutch? a. Ambient temperature switch b. Thermostatic switch c. Pressure cycling switch d. All of the above Answer: d. The thermostatic switch, the pressure cycling switch, and the ambient temperature switch may be connected in series with the compressor’s electromagnetic clutch.

6. Which of the following oils is used in an original equipment R-134a system? a. Mineral oil b. CCOT c. Ester oil d. PAG Answer: d. OEMs use PAG oils in their R-134a systems, ester oils are also used in R134a systems but normally only when an R-12 system has been retrofitted to use R134a.

7. A heating system includes all of the following parts except a ___. a. heater core b. ventilation system c. receiver/dryer d. distribution plenum Answer: c. The receiver/dryer is part of the air-conditioning system, not the heating system.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that a great amount of heat is transferred when a liquid boils or a vapor condenses. Technician B says that a change in pressure does not change the boiling point of a substance. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Technician A is correct. When the pressure of a substance is increased, its boiling point also increases; it does not remain unchanged as stated by Technician B.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

2. Technician A says that suction lines become very warm during A/C operation.

Technician B says that discharge lines connect the compressor to the condenser. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. Suction lines should be cold, not warm, to the touch as stated by Technician A. 3. While discussing the reasons the use of R-134a is being discontinued in some countries: Technician A says that the chemical composition of the refrigerant has been proven to be harmful to the earth’s ozone layer. Technician B says that R-134a leaks contribute to the undesirable greenhouse effect. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. R-134a has little effect on the ozone layer, but has the capability of contributing to the “greenhouse effect” when released into the air.

4. While discussing the reaction by a refrigerant to heat: Technician A says that to absorb heat, the temperature and pressure of the refrigerant are kept low. Technician B says that to dissipate heat, the temperature and pressure are kept high. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. To absorb or dissipate heat, there must be a temperature difference between the refrigerant and the surrounding air.

5. While discussing solar sensors: Technician A says that a solar sensor is a photo diode that receives a 5-volt reference signal from the control module. Technician B says that when the intensity of sunlight increases, the output voltage increases, and as the sunlight decreases, the output voltage decreases. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. Depending on the system, a 5-volt sensor may be used and the output signal voltage will vary based on the amount of light hitting the sensor.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

6. While discussing the future use of CO2 as a refrigerant: Technician A says that CO2 is nontoxic and presents little threat to the environment. Technician B says that only slight changes from conventional systems will be required because CO 2 systems operate at low pressures and temperatures. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. CO2 is non-toxic and when used as a refrigerant there is little environmental concern with its use. Technician B is wrong. CO2 systems operate at pressures that are nearly ten times that of an R-134a system. CO2 also has a critical temperature that is much lower than R-134a. Therefore, everything in the system must be able to withstand the high pressure.

7. Technician A says that when the A/C system is off, the refrigerant occupies the system as a liquid and its pressure is the same throughout the system. Technician B says that refrigerant is pumped out of the compressor as a high- pressure, high-temperature vapor and is sent to the condenser. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician A is wrong. When the system is off, the refrigerant occupies the system as a vapor and its pressure is the same throughout the system.

8. Technician A says that when the refrigerant is pumped out of the compressor and sent to the condenser, heat in the refrigerant is moved to the outside air by conduction and convection. Technician B says that the refrigerant leaves the bottom of the condenser as a high-pressure, high-temperature liquid. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. Heat in the refrigerant is removed by both conduction and convection as air moves over the condenser.

9. A heater does not supply enough heat and the coolant level and flow are correct: Technician A says that a misadjusted heater control could be the cause. Technician B says that a bad thermostat could be the cause. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both Technicians are correct. Problems with the heater control valve and a stuck open thermostat can cause a lack of heat.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

10. While discussing relative humidity: Technician A says that the amount of moisture that air can hold is directly related to the temperature of the air. Technician B says that the colder the air is, the more moisture it can hold. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. The warmer the air, the more moisture it can hold.

TECH MANUAL CONCEPT ACTIVITY 54-1 Air Circulation 1.

Why does the HVAC system allow for outside airflow and recirculated airflow?

Answer Prevent the air inside the passenger compartment from getting stale from a lack of outside air and to increase a/c and heater performance

2. If a vehicle has a complaint of inadequate air circulation, what items should be checked?

Answer Cabin air filter, fresh/recirculated air door operation, obstructions, fan operation

CONCEPT ACTIVITY 54-2 Heater System Identify the components of the heater system below (Figure 54-1).

FIGURE 54–1 Identify the components of the heater system.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

a. __________ Answer Water pump b. __________ Answer Thermostat c. __________ Answer Heater control valve d. __________ Answer Heater hoses e. __________ Answer Heater core f.

__________ Answer Radiator

CONCEPT ACTIVITY 54-3 Heater System 1.

List at least three examples of heat transfer by conduction in the automobile.

Answer Answers will vary but may include: engine to coolant, engine to oil, brake pads/shoes, rear defrost

2. List at least three examples of heat transfer by convection in the automobile.

Answer Answers will vary but may include: radiator to air, condenser to air, evaporator to air, heater core to air, engine to air

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

CONCEPT ACTIVITY 54-4 Air-Conditioning Components 1.

Identify the components of the air-conditioning system in the figure below(Figure 542)

FIGURE 54–2 Label the components of the A/C system a. __________ Answer Compressor b. __________ Answer Evaporator c. __________ Answer Flow control device d. __________ Answer Receiver-dryer e. __________ Answer Condenser

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 54: Heating and Air Conditioning

The air-conditioning system is divided into two sections: the high side and the low side. The high side includes the components that operate at high pressure and high temperature. The low side includes the components that operate at low pressure and low temperature. Using Figure 54-2, identify the components of the high and low sides.

2. High side Answer condenser, receiver-dryer, 3. Low side Answer Evaporator, flow control device, compressor 4. Under what condition(s) are the pressures equal in the air-conditioning system?

Answer When it is off

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

Solution and Answer Guide

ERJAVEC/THOMPSON, AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025, 9780357934616; CHAPTER 55: AIR-CONDITIONING DIAGNOSIS AND SERVICE

TABLE OF CONTENTS Short Answer .......................................................................................................................1 Multiple Choice ................................................................................................................... 3 ASE-Style Review Questions ............................................................................................. 5 Tech Manual ........................................................................................................................ 9 CONCEPT ACTIVITY 55-1 ......................................................................................................... 9 CONCEPT ACTIVITY 55-2 ......................................................................................................... 9

SHORT ANSWER 1.

Explain why special safety precautions must be taken when working with refrigerants.

Answer Answers will vary but may include: Refrigerant can freeze skin and cause frost bite, do not inhale refrigerants, do not vent refrigerants into the atmosphere, always work in well ventilated areas, always wear eye protection.

2. What should you do if you suspect that an alternative refrigerant had been used in the A/C system and it is not performing properly?

Answer When you suspect that an alternate refrigerant has been installed in the system, conduct a purity test and use a refrigerant identifier. Equipment is available to do both of these checks. Knowing what refrigerant is in the system and what condition it is in will help you determine what steps are needed to properly service the system.

3. Explain how dye can be used to find leaks in the A/C system.

Answer Dye is added to the system and then escapes at the location of a leak. The dye is then visible and the cause of the leak can be determined.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

4. What is the purpose of the thermostatic switch in a cycling clutch system?

Answer In cycling clutch systems, a thermostatic switch is placed in series with the compressor clutch circuit so it can turn the clutch on or off. It de-energizes the clutch and stops the compressor if the evaporator is at the freezing point. When the temperature of the evaporator approaches the freezing point, the thermostatic switch opens the circuit and disengages the compressor clutch. The compressor remains inoperative until the evaporator temperature rises to the preset temperature, at which time the switch closes and compressor operation resumes.

5. Why should the probe of an electronic leak detector be placed below the area being checked?

Answer Refrigerant gas is heavier than air, therefore the probe should be positioned below the test point.

6. What customer complaint may be caused by a plugged evaporator drain?

Answer Wet floor and a mildew smell 7. What problems can excessive compressor clutch clearance can cause?

Answer The clutch may slip, causing noise 8. What is the purpose of pulling a vacuum on the A/C system prior to recharging?

Answer To remove any moisture from the system 9. How will air trapped in the A/C system affect system performance?

Answer Air can cause the system’s pressures to be incorrect, cause the system to not cool properly, and allow moisture in the system, which can lead to corrosion. Excessive pressure within the system can restrict the refrigerant’s ability to change its state from gas to liquid within the refrigeration cycle, which drastically reduces its heat absorbing and transferring ability. Moisture, on the other hand, can cause freeze-up at the orifice tube or expansion valve, which restricts refrigerant flow or blocks it completely. Both of these problems result in intermittent cooling or no cooling at all.

Moisture also forms hydrochloric acid when mixed with refrigerant, causing internal corrosion, which is especially dangerous to the compressor.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

MULTIPLE CHOICE 1.

Which of the following statements best defines the term “evacuation”? a. A process in which the refrigerant in a system is released. b. A condition that exists when a compressor runs until there is no refrigerant left in the system. c. The process that pulls all traces of air and moisture from the system. d. A process that uses air to force moisture and dirt out of the system.

Answer: c. Evacuation pulls all traces of air, moisture, and refrigerant from the system.

2. Which of the following statements is true? a. The suction line must be cool to the touch from the evaporator outlet to the compressor. b. The liquid line from the condenser outlet to the evaporator inlet should be cool. c. The evaporator should feel very cold. d. The accumulator must be cool to the touch.

Answer: b. The refrigerant line from the condenser outlet should be hot, not cool.

3. To charge an air-conditioning system while it is running, the refrigerant should be added to ___. a. the high side b. the low side c. both the high and low sides d. either the high or the low side Answer: b. Refrigerant is added to the low side when the compressor is running.

4. All of the following are true statements about flushing an A/C system after a compressor failure, except ___. a. the condenser must be flushed and the receiver/dryer replaced b. filter screens are sometimes located in the suction side of the compressor and in the receiver/dryer. These screens con-fine foreign material to the compressor, condenser, receiver/dryer, and connecting hoses c. use only CFCs for flushing. After the system has been flushed, be sure to oil all components that require it d. some manufacturers recommend replacing the clogged components and installing a liquid line (inline) filter just ahead of the expansion valve or orifice tube instead of flushing the system Answer: c. Compressor failure causes foreign material to pass into the system. The condenser must be flushed and the receiver/dryer replaced. Filter screens are sometimes located in the suction side of the compressor and in the receiver/dryer.

These screens confine foreign material to the compressor, condenser, receiver/dryer, and connecting hoses and should be cleaned or replaced Use only recommended flushing solvents. Never use CFCs or methyl chloroform for flushing. Some recommend instead of flushing the system, replacing the clogged components and installing an inline filter just ahead of the expansion valve or orifice tube.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

5. A very important part of a performance test on an A/C system is a pressure test.

Pressure also is the key to the operation of the system. Which of the following statements is not true? a. Pressure on a substance, such as a liquid, changes its boiling point. b. The greater the pressure on a liquid, the higher the boiling point. c. If pressure is placed on a liquid, the liquid freezes at a higher-than-normal temperature. d. The boiling point can be increased by increasing the pressure on the fluid. It can also be decreased by reducing the pressure or placing the fluid in a vacuum.

Answer: c. Pressure is what the operation of an A/C unit is all about. It also plays an important part in engine cooling and the heating system, as well as a ton of other automotive systems. Certain principles must be known in order to understand and diagnose these systems, some of these facts are: Pressure on a substance, such as a liquid, changes its boiling point. The greater the pressure on a liquid, the higher the boiling point. If pressure is placed on a vapor, the vapor condenses at a higher than normal temperature. In addition, as the pressure on a substance is reduced, the boiling point can also be reduced. For example, the boiling point of water is 212 °F. The boiling point can be increased by increasing the pressure on the fluid. It can also be decreased by reducing the pressure or placing the fluid in a vacuum. Statement C is wrong, pressure on a liquid would not cause it to freeze at a higher temperature. If it did, the coolant in the radiator might freeze because it is pressurized.

6. While conducting a pressure test on an A/C system, the ambient temperature is 80 °F, the low-side gauge reads low (8 psi), and the high side also reads low (85 psi). Which of these could cause these readings? a. Low refrigerant level b. Normal operation c. Bad compressor d. A high-side restriction Answer: a. Both pressure readings are low; this problem is probably caused by a low refrigerant charge. There are many other possible causes for low readings, but none of the other answer choices would cause them. Choice B says these readings are normal and is not true. Choice C suggests that a bad compressor is causing the problem. A bad compressor would typically cause equal pressures on both sides. Choice D sites a restriction on the high-pressure side of the system. If this were the case, both readings would be high.

7. The high-side pressure on a system with a cycling clutch and pressure cycling switch is 145 psi, the low-side pressure is 28 psi, and the ambient temperature is 78 °F. What do these gauge readings indicate? a. The system is undercharged. b. The system is overcharged. c. The system is normal. d. The evaporator pressure regulator is bad.

Answer: c. The gauge readings stated in this question are normal for most systems, especially for a system with a cycling clutch and a pressure switch to cycle the compressor. Low refrigerant level or an undercharge condition would cause the readings to be low. An overcharge condition would result in higher than normal

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

pressures. And, if the evaporator pressure regulator were bad, the high side pressure would be low.

8. When checking an A/C system, the evaporator’s inlet and outlet tubes feel like they are at the same temperature. Which of these could cause this? a. A plugged evaporator b. Correct charge of refrigerant in the system c. Restricted orifice tube d. Leaking condenser Answer: b. Using the sense of touch is good way to diagnose A/C problems. All of the answer choices would not cause the situation except for B. Equal temperatures at the inlet and outlet of the evaporator indicates the system is working normally and to do that, it must have the correct charge of refrigerant in the system.

9. All of these are good reasons for replacing an accumulator unit, except ___. a. the accumulator/dryer is punctured b. the accumulator/dryer is saturated with water c. the A/C system has been open to the atmosphere for 2 or more hours d. the outer shell of the accumulator/dryer is dented Answer: d. An accumulator/drier should be replaced if there is excessive moisture or debris in the A/C system or when the accumulator leaks. A dent in the case of the accumulator doesn’t mean it is defective and replacement is not necessary.

10. In an A/C system, if the low-side pressure is lower than normal, which of the following is the least likely cause? a. A faulty metering device b. Poor airflow across the evaporator c. A restriction in the low side of the system d. The system being overcharged with refrigerant Answer: d. If the low-side pressure is lower than normal, suspect a faulty metering device, poor airflow across the evaporator, a restriction in the low side of the system, or the system is undercharged with refrigerant.

ASE-STYLE REVIEW QUESTIONS 1.

Technician A says that evacuating (pumping down) an air-conditioning system removes air and moisture from the system. Technician B says that evacuating (pumping down) an air-conditioning system removes dirt particles from the system. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. Evacuating the air-conditioning system removes moisture, air, and refrigerant from the system. Dirt particles are trapped in the receiver dryer and are removed when it is replaced.

© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

2. Technician A says that some refrigerant leaks can also be traced to pinholes in the evaporator caused by acid, which forms when water and refrigerant mix. Technician B says that leaks are most often found at the compressor hose connections and at the various fittings and joints in the system. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Acid formation can cause pinhole leaks and connections are common areas for leaks to occur.

3. Technician A says that the presence of oil around a fitting of an air-conditioning line may indicate an oil leak but not a refrigerant leak. Technician B says that using an electronic leak detector is the best way to find the source of a refrigerant leak. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. An electronic leak detector is considered the best method of finding refrigerant leaks. The presence of oil around the fittings indicates both a refrigerant and an oil leak because the refrigerant carries the oil with it as it circulates through the system.

4. Technician A says that a faulty accumulator will allow contaminants to enter the A/C system. Technician B says that a damaged compressor will allow contaminants to enter the A/C system. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. Technician B is correct. A faulty air compressor can produce metal particles that are circulated in the system. A faulty accumulator would be unlikely to allow foreign material to enter the system.

5. Technician A says that air in the system can cause excessive pressure within the system, restricting the refrigerant’s ability to change its state from gas to liquid within the refrigeration cycle. Technician B says that moisture can cause freeze-up at the cap tube or expansion valve, which restricts refrigerant flow or blocks it completely. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Air and moisture in the refrigerant will decrease the cooling ability of the system and can lead to frost and freezing.

© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

6. Technician A feels up and down the face or along the return bends of the condenser for a temperature change and says that there should be a gradual change from hot to warm from the bottom to the top. Technician B says that a restriction in the condenser will be evident by a sudden change in temperature. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: b. A sudden change in temperature indicates a restriction. When checking a condenser, there should be a gradual change from hot to warm as you go from top to bottom, not from bottom to top as claimed by Technician A. 7. Technician A says that a manifold gauge set can be used during the evacuation of the system. Technician B says that a manifold gauge set can be used to diagnose a problem in the A/C system. Who is correct? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. Manifold gauges are commonly used for system service.

8. While discussing an inoperative blend air door: Technician A says that to check the proper functioning of the ductwork, a scan tool may be used to command the door to change position. Technician B says that in some cases you can reach under the dash to reconnect the cable or free a stuck flap. Who is right? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Both technicians are correct. In a blend air system during heater-only operation, the air conditioning unit is shut off, and the evaporator performs no function in air distribution or temperature control. During maximum A/C, the air conditioning system operates, the evaporator is cold, and the blend air door damper is completely closed. Only conditioned air enters the car. As the control lever is moved in the vehicle from max air toward heat with the air conditioner on, the blend air door is moving. In maximum cold, it is completely shut. On maximum hot, it is completely open. To check the proper functioning of the ductwork, move the temperature control lever to see if any change occurs. If it does not, shut off the air conditioner and turn on the heater. Move the temperature control arm again to see if any change occurs. If not, check the cable and the flap door connected to the temperature control lever.

You might be able to reach under the dash to reconnect the cable or free a stuck flap.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

9. Two technicians were discussing how comparing the temperature of a high-pressure line to that of a low-pressure line would help evaluate an A/C system when the system does not have a sight glass. Technician A says that the high-pressure line will feel warmer than the low-pressure line if the system is operating normally. Technician B says that both lines should feel cold after the system has been run for a while if the system is working normally. Who is right? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: a. By feeling the temperature of the lines and components of an A/C system, you can get a good start in your diagnosis whether or not the system has a sight glass.

Feel the liquid line from the receiver/dryer to the expansion valve. The line should be warm for its entire length. The suction line to the compressor should be cool to the touch from the evaporator to the compressor. If it is covered with thick frost, this might indicate that the expansion valve is flooding the evaporator. On vehicles equipped with the orifice tube system, feel the liquid line from the condenser outlet to the evaporator inlet. A restriction is indicated by any temperature change in the liquid line before the crimp dimples the orifice tube in the evaporator inlet. The accumulator as well as the suction line must be cool to the touch from the evaporator outlet to the compressor. Technician A is correct; the high-pressure side should feel hot to the touch, while the low pressure side should feel cold.

10. While conducting an A/C system performance test: Technician A inserts a thermometer into the air duct at the center of the dash and monitors discharge temperature. Technician B follows this test with a complete visual inspection. Who is right? a. Technician A only b. Technician B only c. Both A and B d. Neither A nor B Answer: c. Performance testing provides a measure of air conditioning system operating efficiency. A manifold pressure gauge set is used to determine both high and low pressures in the refrigeration system. The desired pressure readings will vary according to temperature. Use temperature/pressure charts as a guide to determine the proper pressures. At the same time, a thermometer is used to determine air discharge temperature into the passenger compartment. The typical procedure for a performance test follows: Carefully look over all of the components and lines of the system. Connect the manifold gauge set to the respective high- and low-pressure fittings. These fittings are found in various locations within the high- and low-pressure sides of the system. Close the hood and all of the doors and windows of the vehicle.

Adjust the air conditioning controls to maximum cooling and high blower position. Idle the engine in neutral or park with the brake on. For the best results, place a high volume fan in front of the radiator grille to insure an adequate supply of airflow across the condenser. Increase engine speed to 1500–2000 rpm. Measure the temperature at the evaporator air outlet grille or air duct nozzle (35–40 degrees F). Read the high and low pressures, and compare them to the normal range of the operating pressure given in the service manual. Both techs identified steps for a valid performance test.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

TECH MANUAL CONCEPT ACTIVITY 55-1 Air-Conditioning Service Precautions 1.

Locate the air-conditioning service decals for a vehicle assigned to you by your instructor. Describe any safety precautions they contain.

Answer Improper blend door adjustment

2. Refer to the manufacturer’s service information for any system service precautions or safety warnings. Describe them here.

Answer Answers will vary but include: service by trained personnel, do not open the system, wear safety glasses 3. Explain what precautions should be taken when handling refrigerants.

Answer Answers will vary but include: wear safety glasses and gloves, do not breath refrigerant vapor 4. Explain how exposure to refrigerant can cause frostbite.

Answer Refrigerants have very low boiling points and are kept liquid when under pressure.

When refrigerant is allowed to escape it can cause frostbite if exposed to skin

CONCEPT ACTIVITY 55-2 Air-Conditioning Diagnosis Match the following faults with the symptoms given below: no cooling, poor cooling, excessive noise, and water in passenger compartment.

1.

Open compressor clutch coil Answer No cooling

2. Open low-/high-pressure switch Answer No cooling

© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-Conditioning Diagnosis and Service

3. Leaking seals Answer No cooling, poor cooling 4. Loose drive belt Answer No cooling, poor cooling, noise 5. Restricted condenser air flow Answer No cooling, poor cooling 6. Plugged evaporator case drain Answer Water in passenger compartment 7. Improper blend door adjustment Answer Poor cooling

© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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