Circuit Description
WARNING: This page is about a different car, the 2002 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
With low oil pressure, the engine oil pressure switch closes, and the signal circuit is low. With oil pressure above 4.5 psi, the engine oil pressure switch opens, and the signal circuit is high. The PCM monitors the oil pressure switch signal circuit and sends a class 2 message to the BCM indicating the switch status. The BCM sends a message via the serial peripheral interface (SPI) to the IPC in order to illuminate the low oil pressure indicator.