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 a Type A DTC.

DTC P025A is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Engine Controls Schematics

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

1. Ignition OFF, disconnect the harness connector at the K27 FPCM.
2. Ignition OFF, connect a test lamp between the control circuit terminal 13 and ground.
3. Ignition ON, command the G12 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 K20 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 K20 ECM.

4. If all circuits test normal, replace the K27 FPCM.

Perform the Diagnostic Repair Verification

Control Module References