Cummins ISM CM875 (2003-06) Fault Code: 338 PID: S087 SPN: 1267 FMI: 3/3 Idle Shutdown Vehicle Accessories Relay Driver Circuit – Voltage Above Normal, or Shorted to High Source. Open circuit or short to voltage source detected at the idle shutdown vehicl

The ECM monitors the voltage level on this circuit. If it detects a voltage when the signal is commanded OFF, it records this fault code.

Possible causes:

1)ECM Idle Shutdown feature set up incorrectly.
2)Open circuit in the idle shutdown relay, OEM harness, or connectors.
3)Short circuit to a voltage source in the OEM harness or relay.

Possible repair:

1)Replace the idle shutdown relay.
2)Repair or replace the OEM harness.