Head Impact/Side Air Bag Sensors
WARNING: This page is about a different car, the 2002 Toyota Camry. However, it is still accessible from the selected car via links, so may be relevant.
Head impact/side air bag sensor is mounted on right and left center pillars, behind front seat belt retractors. When sensor detects an impact of sufficient force (above a predetermined limit), contacts inside the sensor close, sending a signal to the air bag sensor assembly.