For 1990-2009 cars

### 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 P025A: Fuel Pump Control Module Enable Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open or High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
FPCM Control | P025A | P025A | -- | --

### 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 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.

### Conditions for Running the DTC

The ignition is ON.

### Conditions for Setting the DTC

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.

### Action Taken When the DTC Sets

DTC P025A is a Type A DTC.

### Conditions for Clearing the DTC

DTC P025A is a Type A DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Fuel System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

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 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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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