Engine Oil Pressure Indicator Always On

Engine Oil Pressure Indicator Always On (3.8L)

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 powertrain control module (PCM) should detect a low signal voltage input. With the engine running, the oil pressure switch opens and the PCM detects a high signal voltage input. The PCM tests the state of the EOP signal circuit with the ignition switch turned ON, and the engine turned OFF. When the oil pressure is low, the PCM sends a serial data message to the instrument panel cluster (IPC) requesting the EOP indicator turned ON. The IPC illuminates the EOP indicator when the IPC receives a serial data message from the PCM 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 3.8L engine
* Programming and RelearningProgramming and Relearning