Fuel pump monitor circuit open or short to ground
Fuel pump monitor circuit short to voltage
Damaged Inertia Fuel Shutoff (IFS) switch (if equipped)
Damaged fuel pump control module relay
Engine Light ON (or Service Engine Soon Warning Light)
The Powertrain Control Module (PCM) monitors the Fuel Pump Monitor (FPM) circuit for the presence of a duty cycled signal. If the FPM circuit is fixed at a low or high voltage, the PCM begins to increment a counter. The test fails when the PCM is still not detecting a duty cycled signal on the FPM circuit after a calibrated amount of time.