Engine Oil Pressure Indicator Always On (Switch)

Engine Oil Pressure Indicator Always On (Switch)

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






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 signal circuit with the ignition switch turned ON, and the engine turned OFF. The instrument panel cluster (IPC) illuminates the EOP indicator when the IPC receives a serial data message from the ECM requesting the EOP indicator turned ON.

Circuit/System Testing

Important: Do not turn the key to the crank position or engage the starter at any time during diagnosis.

1. Ignition ON, verify the scan tool Engine Oil Pressure (EOP) Switch parameter is Low.

• If not Low, replace the instrument panel cluster (IPC).

2. Ignition OFF, disconnect the EOP switch.
3. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

• If not OK, test the signal circuit of the EOP switch for a short to ground. If the circuit tests normal, replace the ECM.

• If OK, replace the EOP switch.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Engine Oil Pressure Sensor and/or Switch Replacement for the 4.6L engine
* Engine Oil Pressure Sensor and/or Switch Replacement for the 3.6L engine
* For the IPC or ECM replacement, setup and programming Refer to Programming and Relearning Programming and Relearning