Theory Of Operation

The Engine Oil Pressure Switch is used by the Powertrain Control Module (PCM) to monitor the lubricating oil pressure. The Oil Pressure Switch is normally closed when the engine is not running or oil pressure drops below the engine protection limit, and open when oil pressure is present. This monitor checks for the Oil Pressure Switch state to change from open to closed in a calibrated period of time after the engine is turned off. When the fault is set, the PCM illuminates the MIL and the oil pressure gauge reads zero. The PCM will turn off the oil pressure lamp after the diagnostic runs and passes on the next key cycle.