Cummins ISM CM870 (2003-06) Fault Code: 255 PID: S071 SPN: 632 FMI: 3/3 Engine Fuel Shutoff Valve Drive Circuit – Voltage Above Normal or Shorted to High Source. Open circuit or short to voltage source detected at fuel shutoff valve circuit.

If there is an external shutdown system on the vehicle, make sure it is not miswired and feeding voltage into the fuel shutoff supply circuit.

Possible causes:

1)Open circuit in the engine harness, connectors, or shutoff valve.
?)Fuel shutoff valve signal wire shorted to a voltage source in the harness.

Possible repairs:

1)Replace the fuel shutoff valve.
2)Replace the ECM
3) Replace the engine harness.