C 240 Wagon (203.261) V6-2.6L (112.912) (2003)
Seat Belt Buckle Switch: Description and Operation
The restraint systems seat belt buckle switches (S68/3, S68/4), front left and right monitor the fitting of the three-point safety belt at the driver and front
passenger seats. If not fitted, the airbag unit will ignite at the first release threshold.