Circuit DescriptionThis circuit can be used to control either an exhaust brake or an engine brake depending on the application. The electronic 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 from the ECM.

Conditions for Running the DiagnosticsThis diagnostic runs when the keyswitch is in the ON position and when the pulse width modulated 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 brake 1 circuit pulse width modulated signal is detected to be greater than 0 volts when the pulse width modulated signal is turned off by the ECM.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE light 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 ECM will turn off the amber CHECK ENGINE lamp 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.

Shop TalkPossible causes of this fault code include:

Open circuit in the engine harness, brake harness, or engine brake solenoidsShort to voltage source in the engine harnessMalfunctioning ECM.

Possible Cause:1) Engine Harness failure2) Engine Brake Solenoid3) ECM Failure