P2635
DTC P2635
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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 (FPCM) when the ECM detects that the ignition is on. The voltage from the ECM to the FPCM remains active for two 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.
Conditions for Running the DTC
* The engine is running.
* DTC P0191, P0192, P0193, 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 FPCM detects a predetermined fuel pressure performance degradation between the desired fuel rail pressure and the current estimated fuel rail 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.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Fuel System Description (Fuel System Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
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 FPCM output control. The fuel pump should turn on and off.
Circuit/System Testing
Important: Verify that DTC P0192, P0193, 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, go to DTC P0192 or P0193 (ECM) (P0192)DTC P0192 or P0193 (FPCM) (P0192)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 ohm 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 FPCM.
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 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 FPCM.
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 diagnostic procedure.
Control Module References (Programming and Relearning) for FPCM replacement, setup, and programming