5.2.5. CIS mat

A Capacitive Interior Sensing mat (CIS mat) is installed in the front passenger seat for seat-occupancy detection. This replaces the OC3 mat, which was previously installed for this function. The CIS mat detects whether an adult or a child in a child seat is in the front passenger seat. Deactivation of the front passenger airbag, side airbag and knee airbag is signalled by the illumination of the indicator lamp for front passenger airbag deactivation in the roof function center.

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 capacity and the ohmic resistance between the sensor wire (anode) and the ground of the vehicle (katode) at a frequency of 120 kHz. The CIS mat uses changes in the capacity and the resistance to determine whether an adult or a child is in the front passenger seat.