Abstract: An occupant sensing and crash behavior system for a motor vehicle determines the presence and location of an occupant to then control the deployment of supplemental restraint systems such as air bags or inflatable seat/shoulder belts. Crash anticipation and crash severity sensors provide additional inputs to the system to determine the behavior of the crash and the occupants therein. An infrared sensor emits a plurality of beams to determine the location and position of the occupant as does a proximity sensor located on the air bag door or the occupant seat. Occupant weight plus the presence and orientation of a child seat are considered. Seat belt control is provided to control the length of the seat belt during an impact or crash.