SYMPTOM RELATED DIAGNOSTICS

ENGINE BRAKE VERBAL COMPLAINT (continued)

Test 1

Testing for proper clutch switch operation

Test 2

Checking resistance in the engine harness

1.Verify with a diagnostic tool that the clutch switch operates correctly and that there is approximately 1/2 inch of pedal travel before the clutch status reads “DISENGAGED”.

If the switch does not operate properly, refer to the Switch Diagnostics procedure found later in this section of manual and the Clutch Switch Adjustment procedure in the Repair and Adjustment Procedures section.

2.Once the clutch switch operates properly, test the engine brake.

If the brake works properly, the procedure has fixed the problem. Retest to be sure the problem has been corrected.

If the brake does not work properly, proceed to Test 2.

1.Turn the ignition key to the OFF position.

2.Remove each brake relay from the relay connector.

Dynatard-equipped systems use one relay, while Jacobs Brakes normally use two relays.

3.Measure the resistance from pin 87 of each relay connector to a good ground.

If the resistance is between the specified range, proceed to Test 4.

If the resistance is not in the specified range, find another ground point and retest. If the resistance is still not in this range, proceed to Test 5.

Resistance Ranges (in Ohms)

E7 DynatardE9 DynatardJacobs Dual Relay Jacobs Single Relay 4–62–39.7–14.34.8–7.2

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