Cummins ISB CM550 (1990-94) Fault Code: 374 PID: 1688 SPN: FMI: Fuel Pump Calibration Error

Circuit Description
Fuel pump self-test is provided at power-up. In an ideal case, an active Fault Code 374
indicates a fuel pump defect and can trigger the engine light/malfunction indicator light at key on.

Component Location
The fuel pump is located on the backside of the gear housing. Refer to Procedure 100-002 in
Section E for detailed component location.

Shop Talk
If Fault Code 374 becomes active while the engine is operating, it can possibly be due to a
power glitch or to voltage spikes. Check the power supply circuit for loose or shorted wires and/or fuses. Inspect the power supply relay.