P0523

DTC P0523

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0523
- Engine Oil Pressure (EOP) Sensor Circuit High Voltage

Diagnostic Fault Information






Circuit/System Description

The engine oil pressure (EOP) sensor changes voltage based on the engine oil pressure. The EOP sensor 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 the EOP sensor voltage is within the normal operating range of approximately 1-4 volts. When the engine oil pressure is high, the EOP sensor voltage is high and the ECM senses a high signal voltage. When the engine oil pressure is low, the EOP 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 GMLAN serial data message.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

* The ECM detects that the EOP sensor signal circuit is greater than 4.4 volts.
* 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 diagnostics 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.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the EOP sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 1 and ground.

^ If greater than 1 ohm, test the low reference circuit for a short to voltage or 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 terminal 2 and ground.

^ If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the ECM.

^ 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 terminal 3 and the low reference circuit terminal 1. Verify the scan tool Engine Oil Pressure Sensor parameter display is less than 8 kPa (1.2 psi).

^ If greater than 8 kPa (1.2 psi), test the signal circuit for a short to voltage or an open/high resistance. 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. Verification Tests

* Engine Oil Pressure Sensor and/or Switch Replacement for the 4.3L engine
* Engine Oil Pressure Sensor and/or Switch Replacement for the 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L engine
* Engine Oil Level Sensor and/or Switch Replacement for the 6.6L engine.
* Refer to Programming and Relearning. Programming and Relearning