The seatbelt tensioners have the task of removing or reducing any belt slack in the pelvic and shoulder region. The seatbelt tensioner forms a unit with the seatbelt buckle. The belt buckle switch, a two-wire Hall switch, is monitored by the airbag control unit. In the event of a fault, a fault code memory entry is made in the airbag control unit.
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 unit. The following shows the voltage curve that is measured at the airbag control unit 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 unit, sensors and gas generators only with the battery disconnected!The airbag control unit contains vehicle-specific data and must therefore be encoded before placing into operation!Removal and installation in other vehicles is prohibited!