P062A

P062A-FUEL PUMP CONTROL PERFORMANCE

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 Powertrain Control Module (PCM) detects a difference between the Variable Speed Fuel Pump pressure Actual and Desired. MIL code sets after the failure matures for 60 seconds. When this DTC is set, the Fuel Pump Control Module (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

NOTE: If DTCs P018B, P018C, P018D, P025A, P025B, P025C, P025D, P0627, P0628, P0629, P1205, P1206, P1DBD, or U0109 are present, repair that DTC before proceeding with this test.

1. Turn the ignition on.
2. Using 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 VARIABLE SPEED FUEL PUMP MODULE VARIABLE AND DESIRED PRESSURE
1. Let the engine run until it reaches normal operating temperature.
2. Using the scan tool, go to the PCM Data section and read the Variable Speed Fuel Pump Actual Rail Pressure and the Desired Rail Pressure.

Is the pressure difference >10 psi?

Yes

- Perform the diagnostic procedure for CHECKING THE FUEL DELIVERY SYSTEM. Checking The Fuel Delivery System (Hard Start)

No

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