For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category

### 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 powertrain control module (PCM) 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

• | Engine Controls Schematics for the 2.9L engine

• | Engine Controls Schematics for the 3.7L engine

#### Connector End View Reference

• | Displays and Gages Connector End Views

• | Powertrain Control Module Connector End Views for the 2.9L engine

• | Powertrain Control Module Connector End Views for the 3.7L engine

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Testing

1. Ignition OFF, disconnect the EOP switch.
2. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is Ok.

⇒ | If not Ok, test the signal circuit of the EOP switch for a short to ground. If the circuit tests normal replace the PCM.

3. Ignition ON, perform the lamp test with the scan tool to turn the engine oil pressure indicator off

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

4. If all circuits test normal, test or replace the EOP switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Engine Oil Pressure Sensor and/or Switch Replacement for the 2.9L engine

• | Engine Oil Pressure Sensor and/or Switch Replacement for the 3.7L engine

• | Control Module References for the IPC and PCM replacement, setup, and programming