In-Vehicle Temperature Sensor
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
Sensor is located behind center of dash, right of steering column. A dedicated air hose draws in-vehicle air through aspirator past a sensor to accurately provide temperature readings from inside vehicle. As the air temperature increases, resistance decreases and the remaining voltage is sent back to the IPM providing input from the sensor.