The engine control module (ECM) supplies voltage to the fuel pump flow control module (FPCM) when the ECM detects that the ignition is on. The voltage from the ECM to the FPCM remains active for 2 seconds, unless the engine is in crank or run. While this voltage is being received, the FPCM closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.

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

Control Module References

1. Verify that DTCs P0192, P0193, P0231, P0232, or P023F are not set.

⇒	If the DTC is set, refer to DTC P0192 or P0193 or DTC P0231, P0232, or P023F.

2. Ignition OFF, disconnect the harness connector at the fuel tank B47 fuel pump module.
3. Ignition ON, test for less than 5.0 Ω between the fuel pump module low reference circuit terminal 1 and ground.

⇒	If greater than the specified range, test the fuel pump module low reference circuit for a high resistance. If the circuit tests normal, replace the K27 FPCM.

4. Ignition OFF, install a test lamp between the control circuit terminal 1 and the control circuit terminal 2.
5. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K27 FPCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K27 FPCM.

6. Perform the Fuel System Diagnosis

⇒	If the fuel pressure is not normal, replace the fuel tank B47 fuel pump module.

7. If all circuits test normal, replace the K27 FPCM.

Perform the Diagnostic Repair Verification