Engine Oil Pressure Indicator Malfunction (3.7L engine)

Engine Oil Pressure Indicator Malfunction (3.7L engine)

Diagnostic Instructions

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



Diagnostic Fault Information






Circuit Description

With low oil pressure, the engine oil pressure (EOP) switch closes, and the signal circuit is low. With oil pressure above 4.5 psi, the EOP switch opens, and the signal circuit is high. The engine control module (ECM) monitors the oil pressure switch signal circuit, and sends a class 2 message to the instrument panel cluster (IPC), indicating the switch status.


Reference Information
Schematic Reference

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

Component Connector End Views (Component Connector End 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)for scan tool information


Circuit/System Verification

Ignition ON, engine running, verify the scan tool Engine Oil Pressure Switch parameter is OK.

If not the specified value, refer to Oil Pressure Diagnosis and Testing (Testing and Inspection) .



Circuit/System Testing

Important: Do not turn the key to the crank position or engage the starter at any time during diagnosis.



1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal B and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

• If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal A and the ground circuit terminal B. Verify the scan tool Engine Oil Pressure Switch parameter is Low.

• If not the specified value, test the signal circuit for an open/high resistance. If circuit test normal, replace the ECM.

5. If all circuits test normal, test or replace the engine oil pressure switch.



Repair Instructions

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

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