Circuit DescriptionThe Engine Control Module (ECM) controls engine brakes on cylinders 1, 2, and 3 by sending a signal on the engine brake solenoid number 1 signal circuit. If an engine brake is installed, there will be a jumper harness from this connector to the engine brake pass-through connectors on the rocker lever housing.

Component LocationThe engine brake solenoids are located under the valve cover. The engine brake solenoids are controlled through the engine harness by the ECM.

Conditions for Running the DiagnosticsThis diagnostic runs when the keyswitch is in the ON position and when the pulse width modulated (PWM) device is getting energized or de-energized. In some cases, the diagnostics can also run at some fixed intervals.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the engine brake 1 pulse width modulated (PWM) signal was not detected to be system voltage when the PWM signal was turned on.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.The engine brake 1 circuit will be disabled.Conditions for Clearing the Fault CodeTo validate the repair, drive the vehicle and operate the engine brakes. This will allow the diagnostic to run. If the fault code does not become active again, the repair has been validated.The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkPossible causes of this fault code include:

A short circuit to ground in the engine harnessA malfunctioning engine brake solenoid

Possible Cause:1) Engine harness2) Engine Brake solenoid failure3) ECM calibration