Cummins ISB CM550 (1990-94) Fault Code: 366 PID: 1287 SPN: FMI: Fuel Pump Voltage Measurement Error

Circuit Description
Battery voltage to the fuel pump is passed to the engine control module (ECM) through the controller area network datalink.

Component Location
The voltage measurement is located within the pump control module.

Shop Talk
1) This fault is set when the fuel pump control module registers a voltage value outside of its threshold limits (6.5 to 18-volt) for 0.5 second.
2) The fuel pump fully compensates for voltage fluctuations within its signal range check. Excessive voltage (more than 24-volt) will damage the pump controller.
3) Troubleshooting must focus on sources of high or low voltage or engine grounding.