P0478
Test 1 - 3:
Test 4 - 5:
SYMPTOM
P0478-HIGH VOLTAGE ON THE ENGINE BRAKE DRIVER
WHEN MONITORED
When the ignition is on.
SET CONDITION
When the signal from the engine brake driver output does not match the signal from the engine brake driver feedback.
POSSIBLE CAUSES
- Relay loose
- Engine brake driver control circuit shorted to voltage
- Engine brake relay
- Intermittent condition
- ECM