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

The engine oil pressure (EOP) sensor changes voltage based on the engine oil pressure. The EOP sensor is a 3-wire sensor comprising of the signal circuit, the low reference circuit and the 5-volt reference circuit. The engine control module (ECM) supplies 5-volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM monitors the signal circuit of the EOP sensor to determine the engine oil pressure sensor voltage is within the normal operating range of approximately 1-4 volts. When the engine oil pressure is high, the EOP sensor voltage is high and the ECM senses a high signal voltage. When the engine oil pressure is low, the EOP sensor voltage is low and the ECM senses a low signal voltage. The ECM sends the EOP information to the instrument panel cluster (IPC) via GMLAN serial data message. The IPC illuminates the engine oil pressure indicator when it receives a GMLAN serial data message indicating a low engine oil pressure condition.

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition ON, scan tool installed, perform the Displays Test in the IPC Output Controls Special Functions . Verify that the engine oil pressure (EOP) indicator turns off after the Displays Test.

⇒	If the EOP indicator does not turn off after the Displays Test, test or replace the IPC

Important: Always perform the Diagnostic Repair Verification