Fig. 17.1. Location of the front seat belt tensioner mechanism
The front three-point seat belts have been equipped with a belt tensioner since 1996 (Fig. 17.1). In the event of a collision, the belts are sharply tightened for 10 ms and press the person against the back of the front seat for the next 5 ms. This occurs automatically as soon as the vehicle deceleration exceeds the programmed value. Gas generators ignite and pre-tension the belts. Maintenance of such safety systems must be performed at service centers by specially trained personnel.
Deactivating the belt pre-tensioning mechanism
Work near the seat belt pretensioner should be carried out with extreme caution, as even a light hammer blow or impact wrench vibrations can trigger the sensor and ignite the squibs. For safety reasons, when carrying out all bodywork on the underbody of the vehicle, disconnect the negative battery cable and wait 5 minutes for the airbag and belt pretensioner capacitors to discharge.