GM Service Manual Online
For 1990-2009 cars only

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) Sensor Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Oil Pressure Switch Signal

1

P0520

1

--

Low Reference

--

P0520

1

--

1. Engine Oil Pressure Indicator Malfunction

Circuit/System Description

The engine oil pressure (EOP) 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)/powertrain control module (PCM) should detect a low signal voltage input. With the engine running, the pressure switch opens, and the ECM/PCM should detect a high signal voltage input. When the oil pressure is low, the ECM/PCM sends a serial data message to the body control module (BCM) requesting the EOP indicator turned ON. The instrument panel cluster (IPC) illuminates the EOP indicator when the IPC receives a serial data message from the BCM requesting the EOP indicator turned ON.

Conditions for Running the DTC

The ignition is ON, with the engine ON.

Conditions for Setting the DTC

    • The ECM/PCM detects that the EOP sensor signal circuit is pulled high.
    • 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 diagnostic test fails. The ECM/PCM 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.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster 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, engine running, verify the scan tool Engine Oil Pressure Switch parameter is OK.

If not the specified value, refer:
    •  Oil Pressure Diagnosis and Testing for the 3.8L engine.
    •  Oil Pressure Diagnosis and Testing for the 4.6L engine.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
  2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the ECM/PCM.
  4. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.
  5. If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM/PCM.
  6. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal A and the ground circuit terminal B. Verify the scan tool Engine Oil Pressure Switch parameter is Low.
  7. If not the specified value, test the signal circuit for an open/high resistance. If circuit test normal, replace the ECM/PCM.
  8. If all circuits test normal, test or replace the engine oil pressure switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Engine Oil Pressure Sensor and/or Switch Replacement for the 3.8L engine
    •  Engine Oil Pressure Sensor and/or Switch Replacement for the 4.6L engine
    •  Control Module References for the ECM/PCM replacement, setup, and programming