Rear 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.
Rear air bag sensors are mounted on right and left rear side center pillars, behind rear side seat back assemblies. 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.