P0521

P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE





For complete wiring diagrams refer to Diagrams/Electrical.


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 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. There will be a torque derate issued by the ECM limiting the power output of the engine. The ECM will turn off the torque derate when the oil pressure reading is detected to be within the normal operating range. The ECM will turn off the MIL light after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:

While the key is on.

- Set Condition:

Oil pressure is detected with engine RPM = 0 for 30 seconds.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. OIL PRESSURE SWITCH





Turn the ignition off.

Disconnect the Oil pressure switch harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the oil pressure switch terminal and ground.

Is the resistance less than 10 ohms?

Yes

- Go To 2

No

- Replace the oil pressure switch.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. (G6) SIGNAL CIRCUIT OPEN





Disconnect the ECM harness connectors.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the oil pressure switch (G6) signal circuit between the oil pressure switch harness connector and the ECM harness connector.

Is the resistance less than 10 ohms?

Yes

- Go To 3

No

- Repair the open Oil pressure (G6) signal circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. ECM





Reconnect the ECM harness connectors.

Turn the ignition on.

Measure the voltage between the oil pressure (G6) signal circuit at the oil pressure switch harness connector and ground.

Is the voltage between 4.5 and 5.5 volts?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

No

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