Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 1500. However, it is still accessible from the selected car via links, so may be relevant.
The oil pressure switch is a pressure sensitive switch that is activated by the engine's oil pressure (in the main oil gallery). The oil pressure switch is normally "Closed." The switch changes from a "Closed" circuit to an "Open" circuit, on increasing pressure of 7 psig. The oil pressure switch changes from an "Open" circuit to a "Closed" circuit, on decreasing pressure, between 2 psig and 4 psig. The switch is a two terminal device (one terminal is provided to the wiring harness and the other terminal is the switch's metal housing that screws into the engine block).