A small charge is ignited in the belt tensioner by means of the control device. The gases formed during the explosion push a piston in the tensioner pipe, which is connected to the belt lock through a cable. In this case, the belt buckle is pulled down in such a way that the idle movement of the shoulder and pelvic belt is reduced.
A deployed belt tensioner is detected by the airbag/belt tensioner warning light coming on. When engaged, the seat belt operates as if the tensioner were not present. The belt tensioner is maintenance free. After operation, it must be replaced as a set.
Before disposing of a broken belt tensioner, it must be forcibly neutralized (service station work).
To prevent accidental deployment of the belt tensioner and airbag, you must familiarize yourself with the safety rules for handling the seat belt, refer to Section Power Steering (servo control).
Precautions for handling the seat belt tensioner
Replacing and checking the belt tensioner / airbag system should be carried out at a service station. No structural changes are allowed.
If the belt tensioner has tripped due to an accident, it must be replaced with a new one (service station work).
Disconnect the negative cable before working on the belt tensioner (-) battery. After that, you should isolate the negative pole on the batteries to prevent accidental contact with it.
A removed but unused belt tensioner should be stored under lock and key for long-term vehicle repairs.
The belt tensioner assembly and control unit are shock sensitive. If they fall from a height of more than 50 cm, they cannot be replaced.
When welding, the terminal of the welding machine must be connected directly to the workpiece to be welded. In any case, the control unit must be disconnected from the cable.
The airbag/belt tensioner control unit is located under the center console. To exclude functional disorders, it is impossible to keep magnetizing objects near it.
The belt tensioner unit and the safety device must not be exposed to temperatures above +90°C even briefly. Damaged items cannot be repaired. It is not allowed to open the components of the airbag/belt tensioner system. Check again if the negative cable is disconnected before installation (-) and whether the negative pole of the battery is covered.
Never remove and dispose of the belt tensioner yourself. There is a risk of explosion!
System check
When the ignition is switched on, the airbag/belt tensioner warning light should come on and go out after 4 seconds.
If the control lamp does not light up when the ignition is switched on, this indicates a malfunction in the system. If the lamp does not go out or comes on while driving, there is a malfunction in the airbag/belt tensioner system. In this case, it must be borne in mind that the system is not operational.