Engine Oil Pressure Indicator Malfunction

Engine Oil Pressure Indicator Malfunction

Diagnostic Instructions

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

Diagnostic Fault Information





Circuit/System Description

The engine oil pressure (EOP) switch is a normally closed switch that opens with the proper oil pressure. With the ignition switch turned ON and the engine not running, the engine control module (ECM) should detect a low signal voltage input. With the engine running, the pressure switch opens, and the ECM should detect a high signal voltage input. When the oil pressure is low, the ECM sends a serial data message to the body control module (BCM) requesting the EOP indicator turned ON. The instrument panel cluster (IPC) illuminates the EOP indicator when the IPC receives a serial data message from the BCM requesting the EOP indicator turned ON.

Reference Information
Schematic Reference

Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Instrument Cluster Description and Operation (Instrument Cluster)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, engine running, verify the scan tool Engine Oil Pressure Switch parameter is OK.

If not the specified value, refer:

* Oil Pressure Diagnosis and Testing (Oil Pressure Diagnosis and Testing) for the 4.6L engine.
* Oil Pressure Diagnosis and Testing (Oil Pressure Diagnosis and Testing) for the 3.9L engine.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal B and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

• If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal A and the ground circuit terminal B. Verify the scan tool Engine Oil Pressure Switch parameter is Low.

• If not the specified value, test the signal circuit for an open/high resistance. If circuit test normal, replace the ECM.

5. If all circuits test normal, test or replace the engine oil pressure switch.

Repair Instructions

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

* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 4.6L engine
* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 3.9L engine
* Control Module References (Programming and Relearning) for the ECM and IPC replacement, setup, and programming