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

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Engine running, observe the scan tool Engine Oil Pressure Sensor parameter. The reading should be between 41-448 kPa (6-65 psi).
2. Verify the engine oil pressure, refer to:

•	Oil Pressure Diagnosis and Testing for the 4.8L, 5.3L, 6.0L, 6.2L and 7.0L engine.

•	Oil Pressure Diagnosis and Testing for the 4.3L engine.

•	Oil Pressure Diagnosis and Testing for the 6.6L engine

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) sensor.
2. Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal listed below and ground:

•	Low Reference Terminal 3 (Gas)

•	Low Reference Terminal 1 (Diesel)

⇒	If greater than the specified range, test the low reference circuit for 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 terminal listed below and ground:

•	5-Volts Reference Terminal 2 (Gas)

•	5-Volts Reference Terminal 3 (Diesel)

⇒	If less than the specified range, 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 the specified range, 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 the specified range, test the signal circuit terminal listed below for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

•	Signal Terminal 1 (4.8L, 5.3L or 6.0L Gas)

•	Signal Terminal 2 (6.6L Diesel)

•	Signal Terminal 3 (4.3L Gas)

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

•	Signal Terminal 1 (4.8L, 5.3L or 6.0L Gas)

•	Signal Terminal 2 (6.6L Diesel)

•	Signal Terminal 3 (4.3L Gas)

•	5-Volts Reference Terminal 2 (Gas)

•	5-Volts Reference Terminal 3 (Diesel)

⇒	If less than the specified range, 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, perform the IPC Displays Test with the scan tool. Verify that the engine oil pressure indicator turns ON and OFF when commanded.

⇒	If the engine oil pressure indicator does not turn OFF, replace the IPC.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.