P0231

DTC P0231, P0232, or P023F

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0231
- Fuel Pump Control Circuit Low Voltage

DTC P0232
- Fuel Pump Control Circuit High Voltage

DTC P023F
- Fuel Pump Control Circuit

Diagnostic Fault Information






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 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.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

* The FPCM detects a fault on the fuel pump voltage circuit that is above or below a predetermined voltage threshold.
* The above condition is present for greater than 12.5 milliseconds.

Action Taken When the DTC Sets

* DTC P0231 and P023F are A type DTCs.
* DTC P0232 is a B type DTC.

Conditions for Clearing the DTC

* DTC P0231 and P023F are A type DTCs.
* DTC P0232 is a B type DTC.

Diagnostic Aids

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.

Circuit/System Verification

Ignition ON, command the fuel pump ON and OFF using the scan tool FPCM output control. The fuel pump should turn on and off.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel pump.
2. Connect a test lamp between the control circuit terminal D and ground.
3. Ignition ON, command the fuel pump ON and OFF using a scan tool. The test lamp should turn ON and OFF as commanded.

^ If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the 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 FPCM.

4. Ignition OFF, connect a test lamp between the control circuit terminal A and the control circuit terminal D.
5. Ignition ON, command the fuel pump ON using a scan tool. The test lamp should illuminate.

^ If the test lamp does not illuminate, test the control circuit terminal A for a short to voltage or an open/high resistance. If the circuit tests normal, replace the FPCM.

6. If all circuits test normal, replace the fuel tank fuel pump module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Fuel Tank Fuel Pump Module Replacement (15 Reg Cab w/26 gal Tank) Fuel Tank Fuel Pump Module Replacement (15 Ext/Crew Cab w/26 gal Tank) Fuel Tank Fuel Pump Module Replacement (25 Ext/Crew Cab w/26 gal Tank) Fuel Tank Fuel Pump Module Replacement (15/25 Reg/Ext/Crew Cab w/34 gal Tank) Fuel Tank Fuel Pump Module Replacement (35 Reg/Ext/Crew Cab w/34 gal Tank)