Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel Pump Control - Dual Speed MRFS
The FP signal is a duty cycle command sent from the PCM to the fuel pump control module. The fuel pump control module uses the FP command to operate the fuel pump at the speed requested by the PCM or to turn the fuel pump off. A valid duty cycle to command the fuel pump on, is in the range of 15-47%. The fuel pump control module doubles the received duty cycle and provides this voltage to the fuel pump as a percent of the battery voltage. When the ignition is turned on, the fuel pump runs for about 1 second and is requested off by the PCM if engine rotation is not detected.
FUEL PUMP DUTY CYCLE OUTPUT FROM PCM
| FP Duty Cycle Command | PCM Status | Fuel Pump Control Module Actions |
|---|---|---|
| 0-15% | Invalid off duty cycle | The fuel pump control module sends a 20% duty cycle signal on the fuel pump monitor (FPM) circuit. The fuel pump is off. |
| 37% | Normal low speed operation. | The fuel pump control module operates the fuel pump at the speed requested. The fuel pump control module sends a 60% duty cycle signal on FPM circuit. |
| 47% | Normal high speed operation. | The fuel pump control module operates the fuel pump at the speed requested. The fuel pump control module sends a 60% duty cycle signal on FPM circuit. |
| 51-67% | Invalid on duty cycle. | The fuel pump control module sends a 20% duty cycle signal on the FPM circuit. The fuel pump is off. |
| 67-83% | Valid off duty cycle | The fuel pump control module sends a 60% duty cycle signal on FPM circuit. The fuel pump is off. |
| 83-100% | Invalid on duty cycle. | The fuel pump control module sends a 20% duty cycle signal on the FPM circuit. The fuel pump is off. |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.