Engine Oil Pressure Gage Inaccurate or Inoperative

Engine Oil Pressure Gage Inaccurate or Inoperative

Diagnostic Instructions

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



Diagnostic Fault Information






Circuit/System Description

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, 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 the serial data circuit.


Reference Information
Schematic Reference

Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Instrument Cluster Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)


Circuit/System Testing

1. Ignition ON and the scan tool installed, perform the IPC Gage Sweep Test in the IPC Output Controls. Verify that the EOP gage dials moves from minimum to the maximum value and back to the EOP gage minimum value.

• If the EOP gage does not perform the IPC Gage Sweep Test, replace the IPC.

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

4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and the low reference circuit terminal A.

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

• If less than 550 kPa, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

6. Install a 3-amp fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 8 kPa (1.2 psi).

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

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



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests)

* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 4.6L engine
* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 4.4L engine
* Control Module References (Programming and Relearning) for ECM or IPC replacement, setup and programming