P0231

P0231

Component Location:

General Description
The main relay supplies power to one side of the fuel pump relay coil. The other side of the fuel pump relay coil is ECM/PCM controlled. When the ignition switch is turned ON, the ECM/PCM energizes the fuel pump relay. The ECM/PCM monitors the fuel pump relay control circuit for malfunctions.

DTC Description
If there is a short circuit in the fuel pump circuit, P0231 is set.

DTC Detecting Condition:

Specification:

Schematic Diagram:

Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC).
2. Engine started.
3. Monitor the "Fuel pump relay" parameters on the scantool.






4. Are the parameters displayed correctly?

YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

NO - Go to "Terminal & Connector Inspection" procedure.

Terminal and Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?

YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure.

NO - Go to "Fuel pump relay circuit inspection" procedure.

Control Circuit Inspection
1. Key "OFF".
2. Disconnect fuel pump relay.
3. Key "ON".
4. Measure the voltage between terminal 5 of fuel pump relay harness connector and chassis ground.

Specification : Approx. 3.5 V






5. Is the measured voltage within specifications?

YES - Go to "Component inspection" procedure.

NO - Repair Short to ground in control circuit, and go to "Verification of vehicle Repair" procedure.

Component Inspection
1. Fuel pump relay check
1. Key "OFF".
2. Disconnect fuel pump relay.
3. Measure the resistance between terminal 30 and 87 of fuel pump relay component side.
4 Measure the resistance between terminal 85 and 86 of fuel pump relay component side.

Specification :






5. Is the measured resistance within specification?

YES - Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure.

NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others

NO - Substitute with a known - good Fuel pump relay and check for proper operation. If the problem is corrected, replace Fuel pump relay and go to "Verification of Vehicle Repair" procedure.

Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present?

YES - Go to the applicable troubleshooting procedure.

NO - System is performing to specification at this time.