The Fuel Pump Flow Performance Diagnostic provides a means to detect degradation in the performance of an electronic return-less fuel system that may not be detectable by input and output component circuit diagnostics. It uses fuel pressure error, defined as desired fuel rail pressure minus estimated fuel rail pressure, as the basis for fault determination.

This DTC sets when the FPCM detects a predetermined fuel pressure performance degradation between the desired fuel rail pressure and the current estimated fuel rail pressure.

DTC P2635 is a Type A DTC.

DTC P2635 is a Type  A DTC.

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Fuel Pump Flow Control Module Scan Tool Information for scan tool information

Ignition ON, command the fuel pump ON and OFF using the scan tool ECM output control. The fuel pump should turn ON and OFF.

1. Verify that DTCs P0192, P0193, are not set.

⇒	If the DTCs are set, refer to DTC P0192 or P0193.

2. Ignition OFF, disconnect the X469 harness connector at the LH fuel tank jumper.
3. Ignition OFF, test for less than 5 Ω between the ground circuit terminal G and ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the fuel pump control module relay.

4. Ignition OFF, connect a test lamp between the appropriate signal circuit terminal listed below and ground.

•	LH fuel tank jumper terminal A

•	LH fuel tank jumper terminal B

•	LH fuel tank jumper terminal C

5. Ignition ON, command the fuel pump ON and OFF using a FPCM scan tool controls. The test lamp should turn ON and OFF, as commanded.

⇒	If the test lamp is always ON, test circuit for a short to voltage. If the circuit tests normal, replace the FPCM relay.

⇒	If the test lamp is always OFF, test circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the FPCM relay.

6. If all circuits test normal, perform the Fuel System Diagnosis. Refer to Fuel System Diagnosis

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.