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) Switch Circuit

### Diagnostic Fault Information

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

### Circuit/System Description

The engine control module (ECM) monitors the signal circuit of the engine oil pressure (EOP) sensor. When the oil pressure is high, the sensor is open, and the ECM senses a high signal voltage. When the oil pressure is low, the sensor is closed, and the ECM senses a low signal voltage.

### Conditions for Running the DTC

The ignition is ON, with the engine ON.

### 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 5 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 instrument panel cluster (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.

• | The ECM receives a clear code command from the scan tool.

### Diagnostic Aids

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

### Reference Information

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

• | Displays and Gages Connector End Views

• | Engine Control Module Connector End Views

#### 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 harness connector at the EOP.
2. Ignition ON, install a 3-amp fused jumper between the signal circuit and ground. Verify the scan tool Engine Oil Pressure Switch parameter is Low.

⇒ | If not Low, test the signal circuit of the EOP switch for an open/high resistance. If the circuit tests normal, replace the ECM.

3. 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

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