Circuit Description

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.