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.

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.