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P2635




DTC P2635 (Fuel Pump Control Module)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P2635
- Fuel Pump Performance

Diagnostic Fault Information






Circuit/System Description

The engine control module (ECM) supplies voltage to the fuel pump flow control module when the ECM detects that the ignition is on. The voltage from the ECM to the fuel pump control module remains active for 2 seconds, unless the engine is in crank or run. While this voltage is being received, the fuel pump control module 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 pressure.

Conditions for Running the DTC

* The engine is running.

* DTCs P018B, P018C, P018D, P0231, P0232, P023F, P064A, P1255 or P06A6 are not active.

* DTC P0641 has not failed this ignition cycle.

* Fuel pump control is enabled and the fuel pump control state is normal.

* The system voltage is greater than 11 volts.

Conditions for Setting the DTC

This DTC sets when the fuel pump control module detects a predetermined fuel pressure performance degradation between the desired fuel pressure and the current estimated fuel pressure.

Action Taken When the DTC Sets

DTC P2635 is an A type DTC.

Conditions for Clearing the DTC

DTC P2635 is an A type DTC.

Diagnostic Aids

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.

On vehicles equipped with a high pressure mechanical pump on Direct Fuel Injection engines, the vehicle may continue to run even though the pump in the fuel tank is not operating.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views A/C Compressor Clutch

Description and Operation

Fuel System Description Fuel System Description

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

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

Circuit/System Testing

Note: Do not replace the fuel pump control module based on a history DTC P2635. The DTC P2635 may be stored but that does not indicate a failure of the fuel pump control module. Refer to Strategy Based Diagnosis Strategy Based Diagnosis for further history DTC diagnostics.

Note: Verify that DTCs P018B, P018C, P018D, P0231, P0232, or P023F are not set as current or history before performing this diagnostic. If any of those codes are set as current or history, refer to DTC P018B-P018D P018B or DTC P0231, P0232, or P023F P0231.

1. Ignition OFF, disconnect the harness connector at the fuel tank pump module.

2. Ignition ON, test for 5.0 ohms or less between the fuel pump module low reference circuit terminal 2 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 fuel pump control module.

3. Ignition OFF, install a test lamp between the control circuit terminal 1 and the control circuit terminal 2.

4. 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 fuel pump control module.

• 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 fuel pump control module.

5. Perform the Fuel System Diagnosis Fuel System Diagnosis to verify proper fuel pressure.

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

6. If the fuel system components test normal, refer to Symptoms - Engine Controls Symptoms - Engine Controls.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

Control Module References Programming and Relearning for fuel pump control module replacement, programming and setup

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