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)/powertrain control module (PCM) should detect a low signal voltage input. With the engine running, the oil pressure switch opens, and the ECM/PCM detects a high signal voltage input. The ECM/PCM tests the state of the EOP signal circuit with the ignition switch turned ON, and the engine turned OFF. If the ECM/PCM detects a high voltage input on the EOP signal circuit, DTC P0520 sets. When the oil pressure is low, the ECM/PCM 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/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.
- The ECM/PCM 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. With the ignition ON, install a scan tool and observe the Engine Oil pressure Switch parameter in the IPC ECM/PCM Data List.
2. Disconnect the engine oil pressure switch.
3. Connect a 3-amp fused jumper wire between the signal circuit of the EOP switch and a good ground.
4. With the scan tool installed observe the Engine Oil pressure Switch parameter in the IPC ECM/PCM 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 engine oil pressure 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/PCM.
- If the harness connector is normal, replace the ECM/PCM.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Engine Oil Pressure Sensor and/or Switch Replacement for the 4.6L engine
- Engine Oil Pressure Sensor and/or Switch Replacement for the 3.8L engine
- Control Module References for the ECM replacement, setup, and programming