Belt TENSIONERS
USA/CAN
Other
Never use an ohmmeter or similar tool to test airbags, inflatable curtains, adaptive belt force limiters, adaptive steering column or belt tensioners. Disconnect airbags, inflatable curtains, adaptive seat belt limiters, adaptive steering column or belt tensioners before testing them. Failure to do so may result in accidental deployment, which in turn could result in serious injury or death.
Depending on the market, the vehicle may have up to six belt tensioners. Five of these are located at shoulder height - one for each belt retractor - two in the front (1 and 2) and three in the backseat (3, 4 and 5).
On certain markets there is also a belt tensioner (6) placed in the belt eye located at waist height next to the driver in front. On XC60 there is also, for certain markets, a belt tensioner (6) on the passenger side.
The belt tension contains a pyrotechnical charge that tensions the belt upon deployment.
The 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 respective belt tensioner based on whether the seat belt is in use. The belt tensioner will not be deployed if the seat belt is not fastened. If the seat belts are fastened and seat belt indication in the front seat belt buckles does not function, the belt tensioners will be deployed anyway. Rear belt tensioner deployment is market dependent.
The 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 retractor. When the control module deploys the belt tensioner, the piston is forced downward by the expanding gas. The piston pulls in the steel cable which retracts the belt.
For USA/CAN: the adaptive belt force limiter, belt retractor, belt retractor sensor and belt tensioner are mounted in a unit. If there is a fault in any of these components, the entire unit must be replaced.