Circuit Description
WARNING: This page is about a different car, the 1995 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
Engine oil temperature sensor is a thermistor, similar to a coolant or air temperature sensor. When engine oil temperature is cold, sensor resistance is high and PCM will see a high monitored voltage signal on engine oil temperature sensor circuit. As temperature increases, resistance decreases and PCM sees a lower monitored voltage engine oil temperature sensor circuit.