Engine Oil Pressure Indicator Always On

ENGINE OIL PRESSURE INDICATOR ALWAYS ON




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

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. If the ECM detects a high voltage input on the EOP signal circuit, DTC P0520 sets. When the oil pressure is low, the ECM sends a GMLAN 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 TESTING
With the ignition ON, install a scan tool and observe the Engine Oil Pressure Switch parameter in the ECM Engine Data list.
- If the Engine Oil Pressure Switch parameter displays OK, replace the IPC.
- If the Engine Oil Pressure Switch displays Low, disconnect the engine oil pressure switch, start the engine, and observe the Engine Oil Pressure Switch parameter.
- If the Engine Oil Pressure Switch displays OK, check for poor connection at the harness connector of the EOP switch.
- If the harness connector is normal, replace the EOP switch.
- If the Engine Oil Pressure Switch displays Low, check the signal circuit of the EOP switch for a short to ground.
- If the signal circuit tests normal, check for a poor connection at the harness connector of the ECM.
- If the harness connector is normal, replace the ECM.

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 2.4L engine
- Control Module References for the ECM and IPC replacement, setup, and programming