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 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 brake 1 circuit PWM signal is not detected to be system voltage when the PWM signal is turned on.

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 TalkThe engine brake fault code will only become active once the engine brakes are activated and will remain active until the ECM is powered down. Once the ECM is powered down, the fault code will be inactive until the engine brakes are activated again if the circuit interruption is still present. This tree is designed to troubleshoot an inactive fault code.

Possible causes of this fault code include a short circuit to ground in the engine harness, connector, or engine brake solenoids.

Possible Cause:1) Engine Harness2) Engine Brake Solenoid failure3) ECM failure