The indicator lamp illuminates when you:
• turn the SmartKey to position 1 or 2 in the ignition lock
• on vehicles with KEYLESS-GO, press the Start/Stop button once or twice

If an adult occupant is properly sitting on the passenger seat and the OCS classifies the occupant as an adult, the indicator lamp illuminates and goes out again after approximately 6 seconds.

If the seat is not occupied and the OCS classifies the front passenger seat as being unoccupied, the indicator lamp will illuminate and not go out.

WARNING
If the indicator lamp does not illuminate, the system is not functioning. You must contact an authorized Mercedes-Benz Center before seating any child on the front passenger seat.

For more information, see "Problems with the Occupant Classification System".

WARNING
Never place anything between seat cushion and child seat (e.g. a pillow), since it reduces the effectiveness of the OCS. The underside and rear side child restraint system must be placed entirely on the seat cushion and the backrest of the front-passenger seat backrest.
If necessary, adjust the tilt of the passenger seat backrest.
An incorrectly mounted child seat could cause injuries to the child in case of an accident, instead of increasing protection for the child.
Follow the manufacturer's instructions for installation of child restraint systems.