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 provide an overview of each diagnostic category. |
Diagnostic 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.
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
Circuit/System Verification
Ignition ON, command the fuel pump ON and OFF using the scan tool ECM output control. The fuel pump should turn on and off.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the G12 fuel pump.
- Connect a test lamp between the control circuit terminal 2 and ground.
- Ignition ON, command the G12 fuel pump ON and OFF using a scan tool ECM fuel pump output control. The test lamp should turn ON and OFF, as commanded.
- Ignition OFF, connect a test lamp between the control circuit terminal 1 and the control circuit terminal 2.
- Ignition ON, command the G12 fuel pump ON using a scan tool. The test lamp should illuminate.
- If all circuits test normal, replace the fuel tank G12 fuel pump module.
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K27 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 K27 FPCM. |
| ⇒ | If the test lamp does not illuminate, test the control circuit terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K27 FPCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for FPCM replacement, setup, and programming
