Seat Belt Tensioner

Seat Belt Tensioners







WARNING: Never use an ohmmeter or similar tool to test airbags, inflatable curtains, the adaptive steering column or seat belt tensioners. Disconnect airbags, inflatable curtains, the adaptive steering column or seat belt tensioners before testing them. Failure to do so may result in accidental deployment. This could result in serious injury or death.

Depending on the model and market, there may be up to seven seat belt tensioners in the vehicle. Two in the front seat, three in the rear seats and two in the third row if applicable. The seat belt tensioners contain an explosive charge which tensions the seat belts when deployed. The seat belt tensioners are separated from each other electrically. This means that each seat belt tensioner has a separate individual power supply and ground from the control module.

The seat belt tensioner tensions the seat belt to reduce the forward movement of the body.

This also reduces the forces on the chest from the airbag and seat belt.

The supplemental restraint system module (SRS) determines whether to deploy the seat belt tensioners based on whether the seat belts are being used. The seat belt tensioner will not be activated if the seat belt is not engaged. If the seat belt is fastened and the seatbelt indication does not function for the front seat belt buckles, the seat belt tensioners will be activated anyway.

The seat belt tensioner consists of a pyrotechnical charge and a cylinder with a piston. The piston is connected to a steel cable which is secured to the seat belt reel. When the control module activates the seat belt tensioner the piston is forced downwards by the expanding gas. The piston pulls in the steel cable which reels in the belt.

WARNING: Never use an ohmmeter or similar tool to test airbags, inflatable curtains, the adaptive steering column or seat belt tensioners. Disconnect airbags, inflatable curtains, the adaptive steering column or seat belt tensioners before testing them. Failure to do so may result in accidental deployment. This could result in serious injury or death.