Engine Oil Pressure Gage Inaccurate or Inoperative

Engine Oil Pressure Gage Inaccurate or Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using the diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit Description

The engine oil pressure (EOP) sensor changes resistance based on engine oil pressure. The engine control module (ECM) monitors the signal circuit of the EOP sensor. When the engine oil pressure is high, the sensor resistance is high and the ECM senses a high signal voltage. When the engine oil pressure is low, the sensor resistance is low and the ECM senses a low signal voltage. The ECM sends the engine oil pressure information to the instrument panel cluster (IPC) via the serial data circuit.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the EOP sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 1 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 terminal 3 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 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.

4. Install a 3-amp fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 0.4 volt.

^ If greater than 0.4 volt, 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 3-amp fused jumper wire between the signal circuit terminal 2 and the 5-volt reference circuit terminal 3. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than 4.6 volts.

^ If less than 4.6 volts, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

6. Ignition ON, perform the engine oil gage sweep test with the scan tool.

^ If the engine oil pressure gage does not sweep from its low to high position, replace the IPC.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Engine Oil Pressure Sensor and/or Switch Replacement for the 4.3L engine
* Engine Oil Pressure Sensor and/or Switch Replacement for the 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L engine
* Engine Oil Level Sensor and/or Switch Replacement for the 6.6L engine.
* Refer to Programming and Relearning. Programming and Relearning