Fuel Pump Monitor (FPM) - Dual Speed MRFS
The fuel pump control module communicates diagnostic information to the PCM through the FPM circuit. This information is sent by the fuel pump control module as a duty cycle signal. The 4 duty cycle signals that may be sent are listed in the following table.
NOTE:
The Expedition and Navigator have the event notification signal circuit and an IFS switch. The event notification signal information is calibrated off in the PCM and the IFS switch disables the voltage to the fuel pump control module in the event of a collision. Some vehicles use a fuel pump control module relay located in the body control module (BCM) that is disabled when the BCM detects a crash event. These vehicles do not use an IFS switch nor an event notification signal circuit.
FUEL PUMP CONTROL MODULE DUTY CYCLE SIGNALS
| Duty Cycle | Comments |
|---|---|
| 20% | This duty cycle indicates the fuel pump control module is receiving an invalid duty cycle from the PCM. |
| 40% | For vehicles with event notification signal, this duty cycle indicates the fuel pump control module is receiving an invalid event notification signal from the RCM. For vehicles without event notification signal, this duty cycle indicates the fuel pump control module is functioning normally. |
| 60% | For vehicles with event notification signal, this duty cycle indicates the fuel pump control module is functioning normally. |
| 80% | This duty cycle indicates the fuel pump control module is detecting a concern with the secondary circuits. |