P0523

DTC P0523

DTC DESCRIPTOR
DTC P0523: Engine Oil Pressure (EOP) Sensor Circuit High Voltage.




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

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) or the powertrain control module (PCM) supplies 5-volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM/PCM monitors the signal circuit of the EOP sensor to determine the engine oil pressure 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/PCM senses a high signal voltage. When the engine oil pressure is low, the EOP sensor voltage is low and the ECM/PCM senses a low signal voltage. The ECM/PCM 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/PCM detects that the EOP sensor signal circuit is greater than 4.8 volts.
- The above condition is present for greater than 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The ECM/PCM records the operating conditions at the time the diagnostics test fails. The ECM/PCM 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/PCM receives a clear code command from the scan tool.

CIRCUIT/SYSTEM TESTING
1. With the ignition OFF, disconnect the EOP sensor.
2. With the ignition ON, install a scan tool and observe the Engine Oil Pressure Sensor parameter in the IPC ECM/PCM Data List.
- If the EOP sensor parameter is at or above 8 kPa (1.16 psi), check the EOP sensor signal circuit for a short to voltage.
3. With the ignition OFF, disconnect the negative battery cable and measure the resistance of the EOP sensor low reference circuit.
- If the resistance measured is greater than 5 ohms, check the EOP sensor low reference circuit for an open or a high resistance.
- If the resistance measured is less than 5 ohms, replace the EOP sensor.
- If both circuits tests normal, replace the ECM/PCM.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

- Engine Oil Pressure Sensor and/or Switch Replacement for the 3.5L engine
- Engine Oil Pressure Sensor and/or Switch Replacement for the 3.9L engine
- Engine Oil Pressure Sensor and/or Switch Replacement for the 5.3L engine
- Control Module References for ECM/PCM replacement, setup and programming