CM850 Electronic Control System – FAULT CODE 529

Auxiliary Input/Output 3 Circuit – Voltage Above Normal, or Shorted to High Source


Fault Code: 529
PID: S051
SPN: 703
FMI: 3
LAMP: Amber

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.

None on performance.

Dual Output Signal

Circuit Description

The electronic control module (ECM) provides a signal to the OEM output control solenoid to turn the OEM supplied accessory on and off. The OEM output control circuit varies by OEM. Certain OEM’s may use a solenoid return that is wired to the ECM or may use a return that goes to engine block or chassis ground.

Component Location

The OEM output solenoid location varies by OEM. Refer to appropriate OEM service literature to determine the location.

Shop Talk

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 of this fault include:

  • Open circuit in the engine harness or OEM output control solenoid
  • Short circuit to voltage source in the OEM harness
  • Failed ECM.

Refer to Troubleshooting Fault Code t05-529

Last Modified:  08-Jul-2010