Normal Operation
WARNING: This page is about a different car, the 2005 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.
The engine oil pressure switch is a normally closed switch that is hardwired to the front electronic module (FEM) through circuit 8-GC21 (WH/GN). When the oil pressure is within normal ranges, the engine oil pressure switch opens, removing the ground signal to the FEM. The FEM then sends a signal to the instrument cluster through the communication network to turn off the oil pressure warning indicator. When the oil pressure is low, the engine oil pressure switch closes, grounding circuit 8-GC21 (WH/GN). The FEM then sends a low oil pressure signal to the instrument cluster through the communication network to turn on the oil pressure warning indicator.