For 1990-2009 cars

## DTC P0523 3.6L (LY7)

### 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 0523: Engine Oil Pressure (EOP) Sensor Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Engine Oil Pressure 5-Volt Reference Circuit | P0522 | P0522 | -- | P0521
Engine Oil Pressure Sensor Signal Circuit | P0522 | P0522 | P0523 | P0521
Low Reference | -- | P0523 | -- | P0521

### Circuit/System Description

The engine oil pressure (EOP) sensor changes voltage based on engine oil pressure, and it is a 3-wire sensor comprising of the signal circuit, the low reference circuit and the 5-volt reference circuit. The engine control module (ECM) supplies 5 volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM monitors the signal circuit of the EOP sensor to determine if the engine oil pressure sensor voltage is within the normal operating range of approximately 1-4 volts. When the oil pressure is high, the sensor voltage is high, and the ECM senses a high signal voltage. When the oil pressure is low, the sensor voltage is low, and the ECM senses a low signal voltage. The ECM sends the EOP information to the instrument panel cluster (IPC) via the GMLAN serial data circuit.

### Conditions for Running the DTC

• | The engine keeps running.

• | The DTC P0523 runs continuously once the above condition is present for greater than 10 seconds.

### Conditions for Setting the DTC

• | The ECM detects that the EOP sensor signal circuit is greater than 4.5 volts.

• | The above condition is present for at least 10 seconds.

### Action Taken When the DTC Sets

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

• | The IPC illuminates the EOP 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 the clear code command from the scan tool.

### Reference Information

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

• | Component 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 Verification

1. Ignition OFF, disconnect the harness connector at the fuel oil pressure (EOP) sensor.
2. Ignition OFF, less for less than 1 ohm between the low reference circuit and ground.

⇒ | If greater than 1 ohm, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit and ground.

⇒ | If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Install a 3-Amp fused jumper wire between the signal circuit and the low reference circuit. Verify if the scan tool Engine Oil Pressure Sensor parameter is lower than 4.8 volts or 880 kPa (127.6 psi).

⇒ | If greater than 4.8 volts or 880 kPa (127.6 psi), test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the EOP sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Engine Oil Pressure Sensor and/or Switch Replacement

• | Control Module References