P0520

DTC P0520

DTC DESCRIPTOR

DTC P0520
Engine Oil Pressure (EOP) Sensor Circuit




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) 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 pressure switch opens, and the ECM should detect a high signal voltage input. The ECM tests the state of the EOP circuit with the ignition switch turned ON, and the engine turned OFF. If the ECM detects a high voltage input on the EOP signal circuit, DTC P0520 sets. When the oil pressure is low, the ECM sends a GMLAN 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 OFF.

CONDITIONS FOR SETTING THE DTC
- The ECM 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 records the operating conditions at the time the diagnostic test fails. The ECM displays this information in the Failure Records on the scan tool.
- The 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.
- The ECM receives a clear code command from the scan tool.

CIRCUIT/SYSTEM TESTING

IMPORTANT: Do not turn the key to the crank position or engage the starter at any time during diagnosis.

1. Turn the ignition ON, with the engine OFF.
2. With the ignition ON, install a scan tool and observe the Engine Oil Pressure Switch parameter in the IPC ECM Data List.
- If the Engine Oil Pressure Switch parameter displays OK, disconnect the engine oil pressure switch, connect a 3-amp fused jumper wire between the signal circuit of the EOP switch and a good ground.
3. With the scan tool installed observe the Engine Oil pressure Switch parameter in the IPC ECM Data List.
- If the Engine Oil Pressure Switch parameter displays Low, check for a poor connection at the harness connector of the EOP switch.
- If the harness connector is normal, replace the EOP switch.
- If the Engine Oil Pressure Switch parameter displays OK, check the signal circuit of the EOP switch for an open, for a high resistance or for a short to voltage.
- If the signal circuit tests normal, check for a poor connection at the harness connector of the ECM.
- If the harness connector is normal, replace the ECM.

REPAIR INSTRUCTIONS

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

- Engine Oil Pressure Sensor and/or Switch Replacement
- Control Module References for the ECM replacement, setup, and programming