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.

### DTC Descriptor

DTC P0520 : Engine Oil Pressure (EOP) Sensor Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Engine Oil Pressure Switch Signal | 1 | P0520 | P0520 | --
Engine Oil Pressure Switch Ground | -- | P0520 | 1 | --
1. Engine Oil Pressure Indicator Malfunction

### Circuit/System Description

The engine oil pressure (EOP) switch is a normally closed switch that opens with the proper oil pressure. With the ignition switch turned ON and the engine not running, the engine control module (ECM) should detect a low signal voltage input. With the engine running, the pressure switch opens, and the ECM should detect a high signal voltage input. When the oil pressure is low, the ECM sends a serial data message to the body control module (BCM) requesting the EOP indicator turned ON. The instrument panel cluster (IPC) illuminates the EOP indicator when the IPC receives a serial data message from the BCM requesting the EOP indicator turned ON.

### Conditions for Running the DTC

The ignition is ON, with the engine OFF.

### Conditions for Setting the DTC

• | The ECM detects that the EOP sensor signal circuit is pulled low.

• | The above condition is present for greater than 10 seconds.

### Action Taken When the DTC Sets

• | The ECM records the operating conditions at the time the diagnostic test fails. The ECM displays this information in the Failure Records on the scan tool.

• | The IPC illuminates the engine oil pressure indicator.

### Conditions for Clearing the DTC

• | The DTC becomes history when the conditions for setting the DTC are no longer present.

• | The history DTC clears after 40 malfunction-free warm-up cycles.

### Reference Information

#### Schematic Reference

Instrument Cluster Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Indicator/Warning Message Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. 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

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
2. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

⇒ | If not the specified value, test the signal circuit treminal A for a short to ground. If the circuit tests normal, replace the ECM.

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

⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Engine Oil Pressure Sensor and/or Switch Replacement

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