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.

### Diagnostic Fault Information

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

### Circuit/System Description

The engine oil pressure 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 engine oil pressure switch opens and the ECM should detect a high signal voltage input. When the oil pressure is low, the ECM sends a message via High Speed CAN-Bus to the body control module (BCM). The BCM then sends a message via Low Speed CAN-Bus to the instrument cluster requesting the engine oil pressure indicator turned ON.

### 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

Ignition ON, observe the scan tool ECM - Engine Oil Pressure Switch parameter with the ignition switch turned ON and the engine not running the reading should be Low with the engine running the reading should be OK.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B37 Engine Oil Pressure Switch.
2. Ignition ON, verify the scan tool ECM - Engine Oil Pressure Switch parameter is OK.

⇒ | If not the specified value, test for the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool ECM - Engine Oil Pressure Switch 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 K20 Engine Control Module (ECM).

4. Command the P16 Instrument Cluster All Indicators output function ON and OFF with the scan tool. The engine oil pressure indicator should turn ON and OFF when changing between the commanded states.

⇒ | If the engine oil pressure indicator always on or always off, replace the P16 Instrument Cluster

5. If all circuits test normal, test or replace the B37 Engine Oil Pressure Switch.

### Component Testing

#### Static Test

1. Ignition OFF, disconnect the harness connector at the B37 Engine Oil Pressure Switch.
2. Test for infinite resistance between the signal terminal 1 and ground with the switch in the open position.

⇒ | If not the specified value, replace the B37 Engine Oil Pressure Switch.

3. Test for less than 5 Ω between the signal terminal 1 and ground with the switch in the closed position.

⇒ | If greater than the specified range, replace the B37 Engine Oil Pressure Switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | LINK x Engine Oil Pressure Switch Replacement for LLW.

• | LINK x Engine Oil Pressure Switch Replacement for LXV.

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