Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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 P1189 will set.

Schematic Reference

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition ON, engine ON, verify the scan tool Engine Oil Pressure 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.

4. If all circuits test normal, test or replace the EOP switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.