The oil pressure sending unit uses three circuits. They are:

• A signal circuit to the ECM.
• A sensor ground circuit through the ECM.
• A 5 volt reference circuit from the ECM.

The oil pressure sending unit returns a voltage signal back to the ECM relating oil pressure. Ground for the sensor is supplied by the ECM.

The oil pressure switch is located on the right side of the engine block. The switch screws into the engines main oil gallery.