Circuit Description
WARNING: This page is about a different car, the 1995 Oldsmobile Ninety-Eight and 1995 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.
PCM supplies and monitors voltage of about .45 volt between PCM sensor low reference circuit (Tan wire) and sensor signal circuit (Purple wire). If read with a 10-megohm DVOM, voltage may read as low as .32 volt. Sensor varies voltage within a range of about one volt (rich) to .10 volt (lean). Sensor is like an open circuit and produces no voltage when less than about 600°F (316°C). Open loop operation is caused by open oxygen sensor circuit or a cold sensor.