Electronic Control System Signature, ISX and QSX15 Engines – FAULT CODE 392

Engine Brake Supply Circuit


Fault Code: 392
PID: S029
SPN: 1073
FMI: 11/11
LAMP: Yellow

Less than (+) 6 VDC detected at engine brake circuit 2 when on indicates an excessive current draw from the electronic control module (ECM) or a faulty ECM output circuit.

Engine brakes on cylinders number 2 and 3 can not be activated.

Engine Brake Relay Supply Circuit

Circuit Description

The ECM enables the engine brake by sending a signal directly to the engine brakes. The ECM will only enable the engine brakes under certain operating conditions.

Component Location

The engine brakes are located under the valve cover.

Shop Talk

Possible causes for this fault code include:

  • ECM engine brake circuit 2 has a short circuit to ground.

Refer to Troubleshooting Fault Code t05-392.

Last Modified:  26-Oct-2010