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 via high speed GMLAN to the body control module (BCM). The BCM then sends the EOP information to the instrument panel cluster (IPC) via low speed GMLAN serial data.

Schematic Reference

Connector End View Reference

Component Connector End Views

Scan Tool Reference

Control Module References

1. Ignition OFF, disconnect the harness connector at the EOP sensor.
2. Test for less than 1 ohm of resistance between the low reference circuit and a known ground.

⇒	If greater than 1 ohm, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition OFF, disconnect the harness connector at the EOP sensor.
4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit and a known ground.

⇒	If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the ECM.

⇒	If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Connect an approved test lamp between the 5-volt reference circuit and the signal circuit at the wiring harness connection.

⇒	If the test lamp does not illuminate test the signal circuit for a open/high resistance. If the circuit tests normal replace the ECM.

6. If all circuits test normal, test or replace the EOP sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.