GM Service Manual Online
For 1990-2009 cars only

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 P0230: Fuel Pump Relay Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Fuel Pump Relay Control

P0230³

¹

P0230³

P0230²

Fuel Pump Relay Ground

--

P0230

P0230

³

Fuel Pump Relay Battery Voltage

³

¹

³

²

Fuel Pump Supply Voltage

³

¹

³

²

Fuel Pump Ground

--

¹

³

³

¹ Low current, fuel pump runs slow

² Pump operates continuously, then discharges battery

³ Pump inoperative

Circuit/System Description

An electric fuel pump is used to prime the fuel system after changing the fuel filter or servicing the fuel system. The fuel pump is part of the diesel fuel conditioning module (DFCM) assembly. The fuel pump is powered by the fuel pump relay. The fuel pump relay is controlled by the engine control module (ECM). The ECM enables the fuel pump when the ignition is turn on and will continue to run for 2 minutes or until the engine starts. If the engine does not start due to low fuel pressure and the ignition is left in the on position, the pump will run for up to 2 minutes or until the ignition is turned off. The ECM will also turn off the fuel pump if incorrect voltage is detected on the control circuit. The ECM will need to be powered down with a key cycle during diagnosis or after repairs, before it will command the fuel pump on again.

Conditions for Running the DTC

Ignition is ON.

Conditions for Setting the DTC

    • The ECM detects an incorrect voltage on the control circuit of the fuel pump relay.
    • The above condition exists for 1 second.

Action Taken When the DTC Sets

DTC P0230 is Type C DTC.

Conditions for Clearing the MIL/DTC

DTC P0230 is Type C DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Inline Harness Connector End Views
    •  Engine Controls Connector End Views

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

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Special Tools Required

    • CH-48027 Digital Pressure Gage
    •  J 43244 Relay Puller Pliers

Circuit/System Verification

  1. Install the CH-48027 to the fuel system service port on the right from side of the engine. Command the fuel pump on, using a scan tool and observe the fuel pressure gage. Fuel pressure should be a minimum of 69 kPa (10 psi) with the fuel pump running.
  2. Engine running, observe the DTC information with a scan tool. DTC P0230 should not set.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

  1. Turn OFF the ignition.
  2. Remove the fuel pump relay and turn ON the ignition, with the engine OFF.
  3. Probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground.
  4. Command the fuel pump ON and OFF with a scan tool.
  5. If the test lamp remains illuminated, test the fuel pump relay control circuit for a short to voltage or a faulty ECM.
    If the test lamp does not turn ON and OFF with each command, test the fuel pump relay control circuit for a short to ground or an open. If the circuit tests normal replace the control module.
  6. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the relay.
  7. Command the fuel pump ON and OFF with a scan tool.
  8. If the test lamp does not turn ON and OFF with each command, test the fuel pump relay ground circuit for an open or high resistance.
    If the test lamp turns ON and OFF with each command, replace the fuel pump relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, programing, and setup