Engine Oil Pressure Indicator Always On

Engine Oil Pressure Indicator Always On

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.

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. The ECM tests the state of the EOP circuit with the ignition switch turned ON and the engine turned OFF. 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.

Circuit/System Verification

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

If not the specified value, refer to Oil Pressure Diagnosis and Testing. Component Tests and General Diagnostics

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
2. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

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

3. Ignition ON, install a 3-amp fused jumper between the signal circuit terminal A and ground. 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 the circuit tests normal, replace the ECM.

4. If all circuits test normal, test or replace the engine oil pressure (EOP) switch.

Repair Instructions

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

* Engine Oil Pressure Sensor and/or Switch Replacement for the 3.4L engine.
* Engine Oil Pressure Sensor and/or Switch Replacement for the 3.6L engine.