Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

Possible causes:

1)Open circuit in the engine harness, brake harness, or engine brake solenoids
2)Short to voltage source in the engine harness.
3)Malfunctioning ECM.

Possible repairs:

1)Replace the engine brake solenoid.
2)Replace the ECM.
3)Repair or replace the engine harness.