4.3.7. Deactivation of the airbags
Automatic deactivation of the airbag is provided in order to fulfill the requirements of the National Highway Traffic Safety Administration NHTSA. The child seats listed in the regulation (for an approximately one-year old child on the front passenger seat) must cause deactivation of the airbags.
To do so, a seat-occupancy mat is used to classify the occupant on the front passenger seat. As a further development of the Occupant Classification 3 mat (OC3 mat), the Capacitive Interior Sensing mat (CIS mat) is used in the F10.
The CIS mat consists of two elements: a sensor wire, which runs parallel to the seat heating in the seat cushion and an evaluation unit.
The CIS mat measures the capacitance and ohmic resistance between the sensor wire (anode) and the ground of the vehicle (cathode) at a frequency of 120 kHz. The change in capacitance and resistance enables the CIS mat to determine whether an adult or a child in a child seat is on the front passenger seat.
Deactivation of the front passenger airbag, side airbag and knee airbag on the front passenger side is signalled by the indicator lamp for front passenger airbag deactivation
The indicator lamp for front passenger airbag deactivation in the roof function center is illuminated if a child restraint system tested according to the requirements of the NHTSA with a small child has been detected on the front passenger seat or the front passenger seat is unoccupied.
The brightness of this light is controlled by automatic regulation of the display lighting.