Circuit Description
The electronic control module (ECM) enables the lift pump by sending a signal directly to the
lift pump. The ECM fast-duty cycles the lift pump ON and OFF during cranking, and it enables
the pump once the engine has started.
Component Location
The lift pump is mounted to the engine block on the intake side, toward the rear of the engine.
Shop Talk
1) The lift pump is turned on for approximately 5 seconds when the keyswitch is first turned
ON. With the hood raised, it is possible to hear the lift pump running when the keyswitch
is turned ON.
2) Loose battery connections can sometimes cause this fault code.
Cummins ISB CM550 (1990-94) Fault Code: 278 PID: 73 SPN: 1075 FMI: 11 (Application for Trucks Other Than Ford) Lift Pump Circuit
Cummins ISB CM550 (1990-94) Fault Code: 264 PID: 181 SPN: 174 FMI: 2 Fuel Temperature Sensor Error
Cummins ISB CM550 (1990-94) Fault Code: 261 PID: 168 SPN: 174 FMI: 0 Pump High Fuel Temperature Error/Overheat Error
Cummins ISB CM550 (1990-94) Fault Code: 245 PID: SID 033 SPN: 647 FMI: 4 Engine Fan Clutch Supply Circuit
Cummins ISB CM550 (1990-94) Fault Code: 243 PID: 121 SPN: 513 FMI: 4 Exhaust Brake Supply Circuit
Cummins ISB CM550 (1990-94) Fault Code: 242 PID: 84 SPN: 84 FMI: 10 Vehicle Speed Sensor (VSS Circuit
