Circuit Description
This circuit is internal to the ECM. If the keyswitch is turned off and the ECM still detects
messages being sent from the fuel pump, the ECM will log this fault.
Component Location
This circuit logic is internal to the ECM.
Shop Talk
1) Some older ISB engines use a different original equipment manufacturer (OEM) interface
connector than illustrated.
2) Fault Code 377 can be caused by a stuck fuel pump relay. If voltage is detected at pin 7
of the fuel pump connector, with the keyswitch in the OFF position, check for a faulty fuel
pump relay.
Cummins ISB CM550 (1990-94) Fault Code: 375 PID: SID 254 SPN: FMI: 2 Engine Control Module (ECM) Fuel Calibration Corrupted
Cummins ISB CM550 (1990-94) Fault Code: 375 PID: 602 SPN: FMI: 2 Engine Control Module (ECM) Fuel Calibration Corrupted
Cummins ISB CM550 (1990-94) Fault Code: 374 PID: 1688 SPN: FMI: Fuel Pump Calibration Error
Cummins ISB CM550 (1990-94) Fault Code: 373 PID: SID 233 SPN: 1077 FMI: 3 Fuel Pump Fuel Shut Off Error
Cummins ISB CM550 (1990-94) Fault Code: 373 PID: 232 SPN: 1077 FMI: 3 Fuel Pump Fuel Shut Off Error
