Cummins ISB CM850 (2003-06) Fault Code: 527 PID: SID 154 SPN: 702 FMI: 3 Auxiliary Input/Output 2 Circuit Voltage Above Normal or Shorted to High Source. High signal voltage or open circuit has been detected at the auxiliary input and output 2 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 527 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 repiars:

1)Replace the OEM output control solenoid.
2)Repair or replace the OEM harness.
3)Replace the ECM.