Cummins ISB CM850 (2003-06) Fault Code: 529 PID: SID 51 SPN: 703 FMI: 3 Auxiliary Input/Output 3 Circuit – Voltage Above Normal, or Shorted to High Source. High signal voltage has been detected at the auxiliary input/output 3 circuit.

Cummins ISB CM850 (2003-06) Fault Code: 529 PID: SID 51 SPN: 703 FMI: 3 Auxiliary Input/Output 3 Circuit – Voltage Above Normal, or Shorted to High Source. High signal voltage has been detected at the auxiliary input/output 3 circuit.

The ECM monitors the voltage level on this circuit. When the ECM commands the OEM output signal low, it expects the voltage level to be approximately zero volts. If it detects a high voltage, this fault is recorded. If Fault Code 529 is still active after completing the following troubleshooting steps, consult the OEM service literature for procedures to check the OEM output device for an open circuit or short to ground.

Possible causes:

1)Open circuit in the engine harness or OEM output control solenoid
2)Short circuit to voltage source in the OEM harness
3)Failed ECM.

Possible repairs:

1)Replace the OEM output control solenoid.
2)Repair or replace the OEM harness.
4)Replace the ECM.
5)The removal and installation of the connector may corrected the problem.