The seat belt tensioners have the task of removing or reducing any belt slack in the pelvic and shoulder region. The seat belt tensioner forms a unit with the seat belt buckle. The belt buckle switch, a two-wire Hall switch, is monitored by the airbag control module. In the event of a fault, a fault memory entry is made in the airbag control module.
The belt buckle switches indicate whether the seat belts have been fastened or not. The belt buckle switches are supplied with clocked voltage by the airbag control module. The following shows the voltage curve that is measured at the airbag control module when the voltage curve is OK. For the voltage measurement, the adapter lead must not be connected to the seat belt buckle switch!
Test image for oscilloscope measurement
Note:
All work on the airbag must only be conducted with the battery disconnected!Connect and disconnect airbag control module, sensors and gas generators only with the battery disconnected!The airbag control module contains vehicle-specific data and must therefore be encoded before placing into operation!Removal and installation in other vehicles is prohibited!