P025A

P025A-FUEL PUMP CONTROL CIRCUIT OPEN

For a complete wiring diagram, refer to the Wiring Information.





Theory of Operation

When the Powertrain Control Module (PCM) receives a 'Start' or 'Run' signal from the ignition; It energizes the Fuel Pump relay which sends a continuous 12 volt supply to the Fuel Pump Control Module (FPCM). The PCM also sends a control signal directly to the FPCM which regulates the Pulse Width Modulated (PWM) voltage that will be sent to the Fuel Pump Module. The PWM will vary from 10-100% depending on the input of the Fuel Rail Pressure sensor and other engine demands. The Powertrain Control Module (PCM) receives a Pulse Width Modulated (PWM) signal from the Fuel Pump Control Module (FPCM) representing the state of all inputs and outputs of the FPCM. This is a Constant Pressure Fuel system which means any Delta Pressure test performed on the Fuel Pump would show a continuous pressure (regardless of the changes in PWM). If a pressure sensor fails or other failures are present; The duty cycle goes to Limp mode (100%) to maintain fuel pressure.

- When Monitored:
Engine running. Battery voltage greater than 11.0 Volts.

- Set Conditions:
The Duty Cycle command from the Powertrain Control Module (PCM) to the Fuel Pump Control Module (FPCM) on the FPCM Control circuit is outside the calibrated threshold. Sets the MIL code after the failure matures for 60 seconds. When this DTC is set; The FPCM will continue to run the Fuel Pump Module at 100% duty cycle.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. ACTIVE DTC
1. Turn the ignition on, engine not running.
2. With the scan tool, read DTCs.

Is the DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE (N11) FPCM CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
1. Leave the ignition on, engine not running.
2. Disconnect the FPCM harness connector.
3. Measure the voltage of the (N11) Control circuit at the FPCM harness connector.

Does the voltage measure above 5.2 volts?

Yes

- Repair the (N11) FPCM Control circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. CHECK THE (N11) FPCM CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the (N11) FPCM Control circuit at the FPCM harness connector.

Is the resistance below 5.0 ohms?

Yes

- Repair the (N11) FPCM Control circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE (N11) FPCM CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Leave the ignition off.
2. Measure the resistance of the (N11) FPCM Control circuit between the FPCM harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Repair the (N11) FPCM Control circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.