Seat Occupancy Sensor Pad
WARNING: This page is about a different car, the 2001 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
Front passenger seat cushion is equipped with a foil contact sensor. If front passenger seat is occupied, seat occupancy detector will send a varying analog signal to the SBE. This signal varies in direct proportion to the weight or movement of seat occupant.