Seat Belt Tensioner: Description and Operation

The belt tensioner tensions the seatbelt during a collision which reduces the body's forward movement. The car is equipped with belt tensioners on the driver and front passenger seats.

The belt tensioner consists of a pyrotechnical charge which is detonated by the SRS control module together with the airbag(s). When the charge is detornated, a high gas pressure is generated which drives a piston in an aluminum tube. The piston is connected to the belt roller via a steel wire. The stroke length of the piston is approximately 180 mm which is the maximum length the belt can be rolled up.

The belt tensioner on the driver side is connected to pins 1 and 2 on the SRS control module.

The belt tensioner on the passenger side is connected to pins 3 and 4 on the SRS control module.