Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P2635: Fuel Pump PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open or High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Fuel Pump High Signal | P0231 | P023F | P0232 | P023F, P2635 |
Fuel Pump Low Signal | -- | P023F | -- | P023F, P2635 |
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
Connector End View Reference
Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References 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 DTC P0231, P0232, or P023F.
- Ignition OFF, disconnect the harness connector at the fuel tank pump module.
- Ignition ON, test for 5.0 ohm or less between the fuel pump module low reference circuit terminal 2 and ground.
- Ignition OFF, install a test lamp between the control circuit terminal 1 and the control circuit terminal 2.
- 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.
- Perform the Fuel System Diagnosis to verify proper fuel pressure.
- If the fuel system components test normal, refer to Symptoms - Engine Controls.
| ⇒ | 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. |
| ⇒ | 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. |
| ⇒ | If the fuel pressure is not normal, replace the fuel tank fuel pump module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for FPCM replacement, setup, and programming
