P0521

P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE





For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The Engine Oil Pressure Switch is used by the ECM to monitor the lubricating oil pressure. If the oil pressure drops below the engine protection limit, the switch will open and cause the fault to log. The Engine Oil Pressure Switch is normally closed when the engine is not running and open when oil pressure is present. When the fault is set, the ECM illuminates the MIL light. The ECM will turn off the MIL light after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
With ignition on, engine not running.

- Set Condition:
Oil pressure is detected with engine RPM = 0 RPM's for 30 seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure

1. ENGINE OIL PRESSURE (EOP) SWITCH
1. Turn the ignition off.
2. Disconnect the Engine Oil Pressure (EOP) Switch harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance between the EOP (G6) Signal circuit terminal and ground at the Engine Oil Pressure Switch.

Is the resistance less than 10 ohms?

Yes

- Go To 2

No

- Replace the Engine Oil Pressure Switch.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

2. EOP (G6) SIGNAL CIRCUIT OPEN




1. Disconnect the C1 ECM harness connector.

NOTE: Check connectors - Clean/repair as necessary.

2. Measure the resistance of the (G6) EOP Signal Circuit between the Engine Oil Pressure Switch harness connector and the ECM C1 harness connector.

Is the resistance less than 10 ohms?

Yes

- Go To 3

No

- Repair the open in the (G6) EOP Signal Circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

3. ENGINE CONTROL MODULE (ECM)




1. Reconnect the C1 ECM harness connector.
2. Engine Oil Pressure Switch still disconnected.
3. Turn the ignition on.
4. Measure the voltage between ground and the (G6) EOP Signal circuit at the Engine Oil Pressure Switch harness connector.

Is the voltage between 4.5 and 5.5 volts?

Yes

- Refer to the INTERMITTENT CONDITION - DIESEL Diagnostic Procedure. Intermittent Condition Test

No

- Replace the ECM.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test