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.