Test an oil pressure unit using a multimeter that is set to resistance with the engine off. Test the unit again with the engine running. The process takes only a few minutes.
- Remove the electrical connector
Press the button to disengage the lock. Pull the connector to remove it.
- Test the resistance
With the engine off, connect one lead of the meter to the terminal for the warning light on the sensor, and touch the second lead to the sensor housing. On a properly functioning sensor, the reading is 0 ohms. Connect the lead to the terminal for the sending unit and the metal housing. It should read as an open circuit.
- Start the car
Turn on the ignition switch to start the vehicle for the next phase of testing.
- Check the terminal resistance with the car running
Check the resistance of each terminal again. If there is oil pressure present, the switch terminal should read infinity, which indicates an open circuit. The sending unit reading should be in the 30 to 55 ohm range, depending on the operating temperature, speed and oil viscosity.
- Replace the defective sensor
Turn off the car. If the sensor does not return to the proper settings, it is defective and should be replaced. If the sensor returns the specified settings, reattach the connector.