If a child's seat is fitted on the front passenger's seat, the front passenger's airbags must be disabled. On EU vehicles, disabling is by means of an airbag switch. On US vehicles, disabling is automatic by means of seat occupation detection.
The indicator lamp is activated and lights up when the front passenger's airbag is disabled. The indicator lamp is monitored by the airbag control unit. If a fault in the power supply or lamp is determined, a fault code memory entry is made in the airbag control unit and the airbag warning lamp in the instrument cluster is activated!
The airbag switch can only be activated/deactivated by means of the ignition key when the vehicle is stationary and the door is open.
The airbag switch
The passenger's airbag deactivation switch is 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 passenger's airbag deactivation switch!
Comparison images 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!