Diagnostic Test - Fuel Pump Control Performance Faults (P025B, P027B, P062A, P064A, P26EA)

TECH TIP: The FPCM DTCs will set incorrectly for some vehicles/model years due to incorrect calibrations. For those vehicles it is best to perform the "COMPLETE FUEL PUMP CONTROL MODULE SYSTEM TESTING (NOT DTC SPECIFIC)" diagnostic procedure. Refer to the "KNOW ISSUES" service information above for a list of the vehicles with incorrect calibrations.

FUEL PUMP CONTROL MODULE OUTPUT OVERTEMP (P025B, P027B): This fault will set when the FPCM detects an internal overtemp condition for the fuel pump output circuitry. Anything that can cause excessive current draw can cause the FPCM to eventually overheat and shut down.

Check the wiring and connectors at the FPCM and PCM for signs of spread terminal or corrosion that can cause an excessive electrical load on the FPCM. Check for a high mechanical draw due to a faulty Fuel Pump Assembly or severely restricted filter. Any of these conditions can cause an overtemp condition on the FPCM internal driver circuitry and should be confirmed good before condemning the module.
- If any connection or mechanical issues are found with the module or fuel pump, repair the issue and retest the system.
- If no other issues are found, replace the FPCM in accordance with the service information.

FUEL PUMP CONTROL PERFORMANCE (P062A): This fault usually sets along with other faults since the FPCM will either default to 80% duty cycle, or reduce the duty cycle PWM Output to the Fuel Pump when another fault is present. Either condition can cause the delta between the actual fuel pressure and the desired fuel pressure to be greater than the calibrated thresholds. If this fault is present with any other FPCM related faults, perform the other appropriate diagnostic procedure to find the failure. If only this fault is set, perform this diagnostic procedure.

NOTE:

The Fuel Rail Pressure Sensor is used to detect this failure (Low Fuel Pressure Sensor on the fuel high pressure system engines). A drifted Fuel Rail Pressure Sensor reading due to a faulty sensor or high circuit resistance can cause this DTC to set. The Fuel Rail Pressure Sensor rationality is checked by the PCM at each engine start up event. If it fails it will set a Fuel Rail Pressure Sensor Performance fault. If the Fuel Rail Pressure Sensor Performance fault is present, perform that test procedure before continuing.

If available on the scan tool, check the Fuel Pump duty cycle, the actual and desired fuel pressure data readings.
1. If the duty cycle is 80%, and the actual pressure is approximately 64 - 65 psi, continue testing in step 2.
2. If the actual pressure is lower than the desired pressure, there is likely a fuel pressure issue.
  - Verify that the vehicle is not out of fuel.
  - Check the fuel lines for leaks or restrictions.
  - Before condemning the Fuel Pump, the Fuel Pump PWM Control and return circuits should be checked for high resistance causing low Fuel Pump output. If both circuits check good, the Fuel Pump is most likely faulty.
It is possible to have resistance in Fuel Rail Pressure Sensor signal or sensor ground circuit causing the signal to read off. Check the actual fuel system pressure with a pressure gauge and compare it to the Fuel Rail Pressure Sensor reading on the scan tool. Refer to the CHECKING THE FUEL DELIVERY SYSTEM test procedure for checking fuel pressure. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START) .
1. If the actual fuel pressure and the Fuel Rail Pressure Sensor reading is the same, replace the Fuel Pump. The Fuel Pump Assembly can be failing and still produce high fuel pressure in the system when the FPCM is defaulted to 80% duty cycle.
  - If the actual fuel pressure and the Fuel Rail Pressure Sensor reading is different, continue testing in step 3.
Isolate and check the Fuel Rail Pressure Sensor circuit for high resistance.
1. If any of the circuits measure above 5.0 Ohms of resistance, repair the high resistance.
2. If the circuits check good, replace the Fuel Rail Pressure Sensor.

FUEL PUMP CONTROL MODULE PERFORMANCE (P064A, P26EA): This DTC sets due to an over current condition in the fuel pump circuity. This can occur from high mechanical resistance in the fuel pump or an electrical issue with the fuel pump PWM control circuit. Typically the FPCM will reduce the duty cycle output to the fuel when this failure is occurring to reduce the load on the circuit.

Disconnect the fuel pump control module and fuel pump harness connectors. Check the fuel pump PWM control circuit for continuity to ground.
1. If there is continuity between ground and the fuel pump PWM control circuit, repair the circuit for a short to ground.
2. If the circuit checks good, continue testing in step 2.
Check the fuel pump PWM control circuit for a short to all other circuits at the FPCM harness connector.
1. If there is continuity between the fuel pump PWM control circuit and any other circuit, repair the short between the circuits.
2. If the circuit checks good replace the fuel pump in accordance with the service information.