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 EOP 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

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition OFF, disconnect the harness connector of the EOP sensor.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit and 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 ON, test for 4.8-5.2 volts between the 5-volt reference circuit and 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 tests 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.

4. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 8 kPa (1.2 psi).

⇒	If greater than 8 kPa (1.2 psi), test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal replace the ECM.

5. Install a 3A fused jumper between the signal circuit and the 5-volt reference circuit. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than 550 kPa (80 psi).

⇒	If less than 550 kPa (80 psi), test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. Ignition ON, command the indicators OFF with the scan tool.

⇒	If the EOP indicator does not turn OFF, replace the IPC.

7. If all circuits test normal, replace the EOP sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.