Cummins ISB6.7 CM2150 (2007-09) Fault Code: 2377 PID: SID 033 SPN: 647 FMI: 3 Fan Control Circuit – Voltage Above Normal or Shorted to High Source. Open circuit or high voltage detected at the fan control circuit.

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

The ECM monitors the voltage level on this circuit. When the ECM commands the fan signal low, it expects the voltage level to be approximately 0-VDC. If it detects a high voltage, this fault is recorded.

If Fault Code 2377 is still active after completing the following troubleshooting steps, consult the OEM troubleshooting and repair manual for procedures to check the fan clutch device for an open circuit or short circuit to ground.

Possible causes:

1)An open circuit in the engine harness or fan control solenoid
2)A short circuit to voltage source in the OEM harness
3)A malfunctioning ECM.

Possible repairs:

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