Volt

DTC P2635 - Fuel Pump Control Module

The engine control module (ECM) supplies voltage to the fuel pump 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 rail pressure.

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

DTC P2635 is a Type B DTC.

DTC P2635 is a Type B 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.

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.

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 for scan tool information

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 for further history DTC diagnostics.

1. Verify that DTCs P018C, P018D, P0231, P0232, or P023F are not set.

⇒	If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. Vehicle OFF, disconnect the harness connector at the G12 fuel pump.
3. Vehicle OFF, test for less than 5.0 Ω between the G12 fuel pump low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the G12 fuel pump low reference circuit for a high resistance. If the circuit tests normal, replace the K27 fuel pump control module.

4. Vehicle OFF, install a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
5. Vehicle in Service Mode, 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 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 K27 fuel pump control module.

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

⇒	If the fuel pressure is not normal, replace the G12 fuel pump

7. If all circuits test normal, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the repair.