Mercedes-Benz GLC : Parking Assist PARKTRONIC / Adjusting the volume of the warning tones
Select Warning Tone Volume.
Set a value.
Other information:
M..
If the left-hand rear seat backrest is folded down
and back up again, it may not be possible to pull
out the rear passenger compartment center seat
belt. The seat belt must be released.
Pull the seat belt out approximately 1 in (25 mm) at the seat belt outlet on the seat backrest and then release it again...