Wire Description Wire Number
Wire Color
Wire Number
Description
Wire Color
Power Circuits
Description Accessory Circuits (Continued)
101
RD
Bat (+)
513
OR
A/C Compressor/Refrigerant Pressure SW
103
RD
Dome Lamp
519
PK
Refrigerant Pressure Sw to A/C Unit
105
BR
Key Sw
524
BU
Wiper Cont. to Lower Wiper Motor
109
OR
Alt Output (+) Term.
111
RD
Power to Eng / Pump Control
112
PU
Main Power Relay Output
113
OR
Opr Mon Switch Panel B (+)
114
GN
115
PK
524
GN
Lower Wiper Motor
590
GY
Intermittent Sw to Wiper Cont.
A537
PK
Seat Heater
A586
OR
Wash Sw to Wiper Cont.
Warning Horn (Forward)
A588
GN
Hyd. Lock Solenoid
Cab/Chassis Lamps
C537
GN
A/C Photo Sensor (+)
118
GY
Washer/Wiper
C576
BU
Med. Pressure Sw 1 to Med. Pressure Valve
120
YL
Converter
C577
GY
Med. Pressure Sw 2 to Med. Pressure Valve
124
GN
A/C
C578
YL
Radio Sw
129
BU
Cigar Lighter
C588
BR
Blade Sw to Blade Relay
135
BU
12V Socket
C589
GY
Blade Relay To Solenoids
12V Radio Memory
C591
PK
Floating Blade Relay To Floating Blade Sol.
140
BU
Auto Lubrication Pump
C592
WH
Diodes to Relays
147
PU
Seat Heater
C599
OR
Blade Floating Sw to Blade Floating Relay
149
PU
Boom Lamp
E500
YL
Blade Floating Relay to Blade Relays
150
RD
Hyd. Lock Sw
E501
PU
Blade Relay to Blade Floating Relay
BU
Aux. Ckt
607
PK
Chassis Lamp
154
RD
Neutral Start Limit Sw
615
YL
Cab Lamps
168
RD
Refueling Pump
616
BU
Boom Lamps
172
RD
Engine Gov. Actuator
633
BU
Attach Lighting Ckt
Aux. Ckt
638
WH
763
BU
Travel Speed Sol.
185
YL
Backup
779
WH
Coupler Close Sol
189
RD
Aux. Ckt
780
PU
Coupler Open Sol
191
WH
Aux. Ckt
786
GN
Boom Lamp Relay
788
YL
Engine Sped Sensor (+)
791
PK
Chassis Lamp Relay
Ground Circuits Main Chassis
201
BK
Operator Monitor Return
A755
PK
Throttle Sw #1
210
BK
Converter Output Gnd.
A756
BU
Throttle Sw #2
235
BK
Eng/Pump Control Gnd.
A757
GY
Throttle Sw #3
Basic Machine Circuits
A758
BR
Throttle Sw #4
1
16
1 4
PU
Engine Gov Actuator Feedback
306
GN
Start Relay Coil
A762
PU
Engine Speed Sensor (-)
307
OR
Key Start Sw
A768
BU
Eng/Pump Cont. Sol (+)
308
YL
Main Power Relay Coil
A769
GY
Eng/Pump Cont. Sol (-)
310
PU
Start Aid SW To Start Aid Relay
A770
PK
Electronic Pump Control Bypass Sw to Resistor
311
WH
Start Aid Sw to Key Sw
A771
PU
Implement Pressure Sw
320
OR
Horn Relay Coil
F771
OR
Governor Actuator (A)
321
BR
Travel Alarm
F772
WH
Governor Actuator (B)
322
GY
Warning Horn (Forward)
F773
OR
Governor Accel
323
WH
Fuel Pump Power
F774
WH
Governor Decel
325
PK
Refueling Stop Sw
K779
PU
Alternator D Terminal
327
PK
Fuel Pump Solenoid
877
YL
Air Heater Indicator
334
BU
Air Heater Resistor
878
OR
Start Aid Sol
365
YL
Refueling Relay Coils to Sw
954
GN
Hammer Pressure Sw
376
GN
Coolant Temp Sw
955
BU
Hammer Sol
399
OR
Cold Advance solenoid
K904
GN
Discharge Pump Pressure Sensor
K905
RD
Eng / Pump Control Power
9
K906
GN
Swing Brake Sol
405
GY
Opr Mon Oil Press. (Low Setting)
K907
BU
Swing Brake Sol Signal From Eng/Pump Cont.
412
BU
Opr Mon Coolant Level
K909
BU
Backup Sw
430
BU
Opr Mon Air Filter
K911
PK
E/P Controller - RS 485 (+) E/P Controller - RS 485 (-)
491
PK
Hyd. Oil Temp Sensor
K997
BU
Monitor +B Output
492
GY
Coolant Temp Sensor
L908
OR
E/P Controller RS-232C (TX)
Fuel Level Sensor
L909
Hyd. Oil Level Sw
L968
BU
E/P Controller RS-232C (RX)
OR
EPR Valve (-)
C468
BU
Engine Oil Level
L969
WH
EPR Valve (+)
H414
YL
Overload Warning Switch to Buzzer
L970
GY
Aux. Hyd. Pressure Sw
H415
BR
Overload Warning Pressure Switch to Buzzer
L971
GN
Travel Pressure Sw
L972
BU
Low Idle and Pressure Raise Sw
Accessory Circuits
3 15
B-7
1
Air Heater
C-8
Alarm - Travel
D-9
Alternator
B-8
18
Solenoid - Blade
C-7
22
Buzzer - Overload Warning
F-5
A
Solenoid - Cold Advance
B-9
18
Buzzer - Quick Coupler Warning
H-3
C
Solenoid - Eng/Pump Control
A-7
23
Control - Eng/Pump
C-4
6
Solenoid - Fuel Pump
B-9
18
Control - Wiper
E-2
E
Solenoid - Hammer
G-2
F
B-5 G-7, H-7, I-6, I-9
7
Solenoid - Hyd. Lock
G-2
D
Solenoid - Level Finish
A-7
Converter - 24V to 12V
PU
Radio Speaker - Left
L978
GY
Trenching Sol
509
WH
Radio Speaker - Left (Common)
P975
OR
Quick Coupler Warning Buzzer
511
BR
Radio Speaker - Right
P976
BR
512
GN
Radio Speaker - Right (Common)
8630
BU
Resistor - Fuel Pump
102 - 8016
Resistor - Backup
111 - 9916
Solenoid - Engine/Pump Control
H-9
D
CONN. 2
G-9
D
CONN. 3
G-8
D
CONN. 4
G-8
D
F
CONN. 5
G-8
D
23
CONN. 6
E-8
D
CONN. 7
E-8
D
CONN. 8
E-8
D
A-6
A
Solenoid - Quick Coupler HP Close
A-2
8
CONN. 9
D-8
D
Ground - Cab
D-2
E
Solenoid - Quick Coupler HP Open
A-2
8
CONN. 10
G-7
D
Quick Coupler Sol
Ground - Chassis
B-3
8
Solenoid - Quick Coupler LP
G-2
F
CONN. 11
F-6
F
Rotating Beacon Sw
Ground - Chassis
B-8
4
Solenoid - Start Aid
F-9
24
CONN. 12
F-6
F
Ground - Platform
D-5, G-3, G-6
F
Solenoid - Swing Brake
A-2
22
CONN. 13
E-6
F
CONN. 14
E-6
F
CONN. 15
E-6
F
Contact Position Normally Closed Normally Open Normally Open Normally Open Normally Open Normally Open
Resistance
(Ohms)1
17.6 ± 0.6 6.0
Ground - Relay Panel
H-9
D
Solenoid - Travel Speed
A-7
23
Ground Strap - Chassis
G-9
D
Solenoid - Trenching
A-7
23
CONN. 16
C-6
10
Ground Strap - Chassis to Engine
A-8
9
Switch - Air Cleaner
F-8
D
CONN. 17
C-6
10
Ground Strap - Chassis to Platform
G-6
10
Switch - Air Heater/ Start Aid
E-4
C
CONN. 18
C-5
10
Horn
C-2
8
Switch - Aux.
E-5
C
CONN. 19
C-5
10
Indicator - Hyd. Oil Filter
A-7
11
Switch - Backup EPR Valve
D-4
C
CONN. 20
B-5
F
CONN. 21
B-5
F
CONN. 22
C-5
F
CONN. 23
C-5
27
Joystick - Multiswitch LH
I-2
B
Switch - Backup Gov.
D-5
C
Joystick - Multiswitch RH
F-3
C
Switch - Blade Floating
F-3
C
Meter - Service
F-2
E
Switch - Boom Raise Pressure
C-7
22
CONN. 24
H-5
F
Monitor
F-2
E
Switch - Coolant Level
E-9
25
CONN. 25
H-5
F
Motor - Lower Wiper
H-2
12
Switch - Coolant Temp
B-9
18
CONN. 26
H-4
F
Motor - Starter
A-8
9
Switch - Coolant Temp (Start Aid)
C-8
18
CONN. 27
H-4
F
CONN. 28
I-3
C
CONN. 29
D-3
F
CONN. 30
B-3
16
Motor - Upper Wiper
G-1
13
Switch - Disconnect
G-9
D
Motor - Washer
E-9
D
Switch - Engine Oil Level
B-8
26
Pickup - Engine Speed
B-9
14
Switch - Engine Oil Pressure
A-9
18
CONN. 31
A-2
20
Pump - Auto Lubrication
E-9
15
Switch - Hammer Pressure
G-2
F
CONN. 32
B-2
16
Pump - Refueling
B-2
16
Switch - Hyd. Oil Level
B-7
19
CONN. 33
B-2
16
Relay - Air Heater
I-7
D
Switch - Implement Pressure
B-7
22 C
I-9
D
Switch - Key Start
E-3
Relay - Blade
I-7, I-9
D
Switch - Neutral Start Limit
I-2
B
Relay - Blade Floating
I-7, I-8
D
Switch - Overload Warning
E-4
C
Relay - Boom Lamp
J-8
D
Switch - Overload Warning Pressure
D-2
F
Relay - Cab/Chassis Lamp
I-9
D
Switch - Quick Coupler
I-3
C
Relay - Fan
I-7
D
Switch - Radio
E-4
C
Relay - Horn
I-9
D
Switch - Refrigerant Low Pressure
B-9
18
Relay - Hyd. Lock Sol
I-8
D
Switch - Refueling
A-2
16
Relay - Main
H-7
D
Switch - Refueling Start
B-2
16
6130 to 7500
Relay - Neutral Start
I-7
D
Switch - Refueling Stop
B-3
16
4.0 ± 0.2
Relay - Refueling 1
B-2
17
Switch - Rotating Beacon
E-5
C
47.00 ± 2.35
Relay - Refueling 2
B-2
17
Switch - Seat Heater
E-4
C
Relay - Start
H-7
D
Switch - Throttle Position
E-3
C
11.7 ± 1.2
112 - 4009
Sender - Coolant Temp
20824 - 25451 @ 0 C (32 F) 6134 - 7496 @ 25 C (77 F) 475 - 522 @ 100 C (212 F)
121 - 1490
Solenoid - Level Finish Solenoid-Trenching
32.0 ± 3.2
121-1491
Solenoids -Hydraulic Lock Solenoid - Swing Brake Solenoid - Travel Speed
32.0 ± 3.2
140 - 2238
Resistor Coolant Temp
Governor actuator does not move.
2304
Calibration data error.
3201
Monitor RAM is not normal.
4101
Electric power supply to the controller is too much (43 volts).
4102
Over-current in proportional reducing valve.
4103
Proportional reducing valve circuit is open.
4104
Monitor power supply (digital output) over current.
4105
Over-current in digital output (trenching solenoid).
4106
Over-current in digital output (fine control solenoid).
4107
Over-current in digital output (travel speed change solenoid).
4108
Over-current in digital output (travel alarm).
410A
Over-current in digital output (swing brake solenoid).
4201
Engine speed is not normal.
4202
Engine coolant temperature sensor is shorted to body ground.
4203
Hydraulic oil temperature sensor is shorted to body ground.
4204
PWM sensor of pump delivery pressure is shorted to body ground.
4207
PWM sensor of pump delivery pressure is open in circuit.
420A
Fuel sensor is shorted to body ground.
420B
Fuel sensor is open or shorted to battery voltage.
420C
Electric power supply is to low (below 23 volts).
420D
Electric power supply is to high (above 32 volts).
420E
Engine speed dial is not in one of the 10 specified positions.
4301
Data mismatch 1 between alternator and speed sensor (alternator is abnormal).
4302
Data mismatch 2 between alternator and speed sensor (speed sensor is abnormal).
4303
Engine stalls.
A201
Monitor communication is not normal.
A202
Monitor takes too much time to respond to controller's signal.
A203
Communication is abnormal in controller.
25.00 ± 0.25
Title Alternator:
Switch - Travel Pressure
B-7
22
Resistor - Air Heater
H-7
D
Switch - Windshield
E-2
A
Engine/Pump Control:
Resistor - Backup
I-9
D
Switch Panel
F-3
C
Starting and Charging:
Resistor - Coolant Temp
H-7
D
Unit - A/C
H-6
7
Resistor - Fuel Pump
H-7
D
D = Located in relay panel area. E = Located in dash area. F = Located under cab floor plate.
This indicates that the component has a wire connected to it that is connected to ground.
This indicates that the component does not have a wire connected to ground. It is grounded by being fastened to the machine. Reed Switch - A switch whose contacts are controlled by a magnet. A magnet closes the contacts of a normally open reed switch; it opens the contacts of a normally closed reed switch. Sender- A component that is used with a temperature or pressure gauge. The sender measures the temperature or pressure. Its resistance changes to give an indication to the gauge of the temperature or pressure.
T
Relay (Magnetic Switch) - A relay is an electrical component that is activated by electricity. It has a coil that makes an electromagnet when current flows through it. The electromagnet can open or close the switch part of the relay. Solenoid - A solenoid is an electrical component that is activated by electricity. It has a coil that makes an electromagnet when current flows through it. The electromagnet can open or close a valve or move a piece of metal that can do work.
Harness And Wire Symbols
Socket
Wire Color
Single Wire Connector
Circuit Number Identification
SENR3685
132 - 7834
SENR9291
Ground Connection
Fuse
AA
105-9344
1 Receptacle
Wire Gauge
Form Number 109 - 2362
Component Part Number
Wire, Cable, or Harness Assembly Identification
325-PK-14
D
B = Located in operator's left hand console area.
Normally closed switch that will open with an increase of a specific condition. No circle indicates that the wire cannot be disconnected from the component.
A
Related Electrical Service Manuals
Circuit Breaker Symbol
Flow Symbol
Level Symbol
Temperature Symbol
Normally open switch that will close with an increase of a specific condition (temp, press, etc...). The circle indicates that the component has screw terminals and a wire can be disconnected from it.
Pin
I-7
Machine locations are repeated for components located close together.
Printed in U.S.A.
T
Pressure Symbol
CONN. 34 C-2 8 The connectors shown in this chart are for harness to harness connectors. Connectors that join a harness to a component are generally located at or near the component. See the Component Location Chart.
Relay - Timer
C = Located in operator's right hand console area. At room temperature unless otherwise noted.
CONN. 1 - S.I.S. Connector
Ground - Cab
A = Located in operator's compartment.
1
Machine Location
22
Resistor, Sender and Solenoid Specifications
5L - 2854
Schematic Location
Connector Number
A-2
Relay - Aux. Hyd.
41 - 5394
Governor actuator feedback signal deviates.
2303
Connector Location
Solenoid - Medium Pressure Valve
With increasing pressure the closed condition can be maintained up to 2800 kPa (405 psi), with decreasing pressure the closed condition can be maintained down to 170 kPa (25 psi).
Solenoid - Start Aid
Governor actuator feedback signal is not stable.
2302
Electrical Schematic Symbols And Definitions
B
1
Sender - Hydraulic Oil Temp
Governor actuator feedback sensor circuit is shorted to body ground.
2301
©2001 Caterpillar All Rights Reserved
I-4, I-5, I-6
Off Machine Switch Specification
3E - 6332
E
D
508
Solenoid - A/C Clutch
F-2
G-9
Fuses - 10A & 15A
3E - 1906
Sensor - Provision For A/C Photo
Breaker - Main
Level Finish Sol
Component Description
20
4
21
YL
Part No.
19
A-2
A-9
L977
Refrigerant Hi/Lo Pressure
B-7
Sensor - Fuel
A-9
Washer - Front
113-3444
Sender - Hyd. Oil Temp
3
Solenoid - A/C Compr Clutch
PU
Engine Oil Pressure
2
Sensor - Pump Discharge Pressure
506
107-0611
Machine Location 18
5
Diodes
Hammer Pressure
Sender - Coolant Temp
Schematic Location B-8
Component
D
Refueling Start Sw to Refueling Relays 1 & 2
26.7 C MIN (80 F MIN) 882.0 kPa MIN (127.92 psi MIN) 2156.0 ± 196.0 (312.7 ± 28.43 psi) 290.0 kPa MIN (42.06 psi MIN) 70.0 ± 21.0 kPa (10.15 ± 3.05 psi) _ _
Governor actuator feedback sensor circuit is open or shorted to battery voltage.
2202
F
F-9
Boom Raise Pressure Sw
106-0181
16
G-9
GN
Boom Raise Pressure
17
Breaker - Alternator
GN
106-0180
6
Batteries
L976
106-0179
27
Actuator - Engine Gov.
L974
Implement Pressure Travel Pressure
23
Machine Location
Wiper - Front (Low)
37.8 ± 2.8 C (100 ± 5 F) 1225.0 ± 98.0 kPa (177.67 ± 14.21 psi) 2646.0 ± 196.0 kPa (383.77 ±28.43 psi) 490.0 ± 49.0 kPa (71.07 ± 7.11 psi) 93.0 ± 21.0 kPa (13.49 ± 3.05 psi) 196 to 3140 kPa1 (28.4 to 455.4 psi)
Battery voltage is not normal.
2201
12
10
Schematic Location
Wiper - Front (Park)
Deactuate
Air filter is clogged.
1305
E
C
B
Component
BR
Actuate
Hydraulic oil temperature is too high.
1304
8
D
5
GN
Coolant Temperature
20
19
25
501
8N-1693
11 14
500
Function
Engine coolant temperature is too high.
1303
22
18
Component Location
Alternator (R) Term.
GN
1302
Machine Harness Connector And Component Locations
GN
K912
312B L: 9FS1-UP 2KW1-UP
Engine oil pressure is too low.
24
26
403
Hyd. Oil Filter Indicator
312B: 6SW1-UP 9NW1-UP
Description of Problems
1301
7
A761
Monitoring Circuits
312B and 312B L Excavator Electrical System
21
Starter Relay No. 1 Output
Part No.
23
21
2
WH
WH
11
13
304
496
17 9
A
Aux. Ckt
GN
14
19
Control Circuits
Main Breaker
GN
495
8
Rotary Beacon
180
OR
22 2
Lighting Circuits
Hyd. Lock Coil Relay
152
487
E
20
OR
BK
C
6
10
26
139
200
Code
12
4
A/C Photo Sensor (-)
RD
Real Time Error Codes
13
18
OR
177
F
A
3
C538
YL
7
D 27
Fan Relay
176
B
25
BR
GN
5
15
116
151
RENR1115-02 April 2001
24
Plug 2
200-BK-14
Pin or Socket Number
SENR9292
1 2
Typical representation of a Deutsch connector. The plug contains all sockets and the receptacle contains all pins.
1 2
Typical representation of a Sure-Seal connector. The plug and receptacle contain both pins and sockets.