Mercedes-Benz GLS Operator's Manual page 229

Slide bolt A into the hole in the ball coupling
X
recess and the ball coupling to the stop.
Secure the bolt using spring cotter B.
X
Check the ball coupling, bolt and spring cotter
X
for correct installation.
If the ball coupling cannot be correctly mounted,
remove the ball coupling. Under these circum-
stances, the ball coupling must not be used for
trailer towing.
Have the entire trailer tow hitch checked at a
qualified specialist workshop.
Coupling up a trailer
!
Do not connect the trailer's brake system (if
featured) to the hydraulic brake system of the
towing vehicle, as the latter is equipped with
an anti-lock brake system. Doing so will result
in a loss of function of the brake systems of
both the vehicle and the trailer.
Shift the transmission to position P.
X
Apply the vehicle's electric parking brake.
X
Start the engine.
X
Vehicles with AIRMATIC package: select
X
normal level and the Comfort drive program.
Switch off the engine.
X
Close the doors and tailgate.
X
Couple up the trailer.
X
Establish the electrical connection between
X
the vehicle and the trailer.
Check that the trailer lighting system is work-
X
ing.
Push the combination switch upwards/down-
X
wards and check whether the corresponding
turn signal on the trailer flashes.
A trailer that is connected is recognized only
when the electrical connection is established
correctly and when the lighting system is work-
ing properly. The function of other systems also
depends on this, for example:
®
ESP
R
Parking Assist PARKTRONIC
R
Parking Pilot
R
Active Blind Spot Assist
R
Active Lane Keeping Assist
R
i
Vehicles with the AIRMATIC package: if you
couple up a trailer, the vehicle always remains
at normal level. When coupling up a trailer,
please observe the following:
If the normal level has not been set man-
R
ually, the vehicle is automatically lowered
to normal level. This is the case if a speed of
5 mph (8 km/h) is reached.
The Sport drive program is not available.
R
These restrictions apply to all accessories
powered through a connection to the trailer
power socket of your vehicle, e.g. a bicycle
carrier.
Observe the maximum permissible trailer
dimensions (width and length).
Towing a trailer
Z
227