Seat Weight Sensor
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
Vehicles equipped with the Occupant Classification System (OCS) have a seat weight bladder and pressure sensor unit that is integral to the passenger side front seat cushion. The pressure sensor receives a nominal five volts and a ground through dedicated hard wired circuits from the OCM. The OCM then monitors the pressure sensor output voltage.