The engine control module (ECM) supplies a high voltage signal to the fuel pump control module (FPCM) when the ECM detects that the ignition is on. The high voltage signal from the ECM to the FPCM remains active for two seconds, unless the engine is in crank or run. While this signal 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.

The FPCM detects a fault on the fuel control enable signal circuit.

DTC P025A is an A type DTC.

DTC P025A is an A type DTC.

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

Important: Repair all U-codes before performing this diagnostic.

1. Ignition OFF, disconnect the harness connectors at the ECM X1 and the FPCM.
2. Ignition ON, test for 0 volts between the FPCM harness connector terminal 13 and ground.

⇒	If greater than the specified voltage, test the fuel control enable signal circuit for a short to voltage.

3. Ignition OFF, test for infinite resistance between the FPCM harness connector terminal 13 and ground.

⇒	If less than the specified range, test the fuel control enable signal circuit for a short to ground.

4. Ignition OFF, test for 1.0 ohm or less between the ECM harness connector X1 terminal 50 and FPCM harness connector terminal 13.

⇒	If greater than the specified range, test the fuel control enable signal circuit for an open/high resistance.

5. Reconnect the harness connectors at the ECM and the FPCM. Within 2 seconds of ignition ON, with a scan tool, verify that the Fuel Pump Command parameter displays ON.

⇒	If the parameter does not display ON within the 2 seconds of ignition ON, replace the ECM.

6. If all circuits test normal, replace the FPCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM or FPCM replacement, setup, and programming

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 supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.

The ignition is ON.

The GMLAN serial data message from the ECM to the FPCM does not agree with the state of the control enable voltage signal supplied from the ECM to the FPCM for more than 2 seconds.

DTC P025A is an A type DTC.

DTC P025A is an A type DTC.

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

1. Ignition OFF, disconnect the harness connector at the FPCM.
2. Ignition OFF, connect a test lamp between the control circuit terminal 13 and ground.
3. Ignition ON, command the fuel pump ON and OFF with a scan tool ECM fuel pump output control. 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 ECM.

⇒	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 ECM.

4. If all circuits test normal, replace the FPCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM or FPCM replacement, setup, and programming