Mercedes-Benz GLC Owner's Manual page 311

Towing a trailer
308
To ensure reliable operation of the failure
indicator, each LED chain in the trailer lighting
must be guaranteed a minimum current of
50 mA.
Trailer with 7-pin connector
General notes
Trailer with 7-pin connector: you can con-
nect to the 13-pin socket on the ball coupling
using an adapter or, if necessary, an adapter
cable. Both can be obtained at a qualified
specialist workshop.
Fitting the adapter
! Make sure that there is sufficient cable
play so that the cable cannot become
detached when cornering.
! Remove the installed adapter cable
before folding in the ball coupling. Other-
wise, damage may occur to the rear
bumper and the adapter cable.
Open the socket cover.
X
Insert the plug connector with lug : into
X
groove = on the socket.
Turn bayonet connection ; around clock-
X
wise to the stop.
Let the cover engage.
X
If you are using an adapter cable, secure
X
the cable to the trailer with cable ties.