Oil Pressure Switch

The oil pressure switch is a normally open switch that is hardwired to the PCM through a single signal circuit. The ground is provided by the switch housing when it is mounted on the engine. The PCM provides a reference voltage to the oil pressure switch. When oil pressure is low, the oil pressure switch remains open, sending the reference voltage high. When the oil pressure is sufficient, the oil pressure switch closes, pulling the reference voltage low to the PCM.