Mercedes-Benz GLC Owner's Manual page 313

Towing a trailer
310
Problem
Unlocking using the
button in the driver's
door (all vehicles
apart from PLUG-IN-
HYBRID):
The ball coupling does
not swivel, even
though:
the vehicle is station-
R
ary
no trailer cable is
R
connected.
The ball coupling does
not swivel. The indica-
tor lamp in the button is
flashing permanently.
The Trailer cou‐ Trailer cou‐
pling Check lock pling Check lock
message appears in the
multifunction display.
Possible causes/consequences and M M Solutions
The on-board voltage is too low.
Engage park position P.
X
Switch on the power supply.
X
or
Start the engine.
X
If the ball coupling still does not unlock:
Consult a qualified specialist workshop.
X
There is a malfunction in the release electronics.
When the ball coupling is retracted: pull and hold the button
X
in the tailgate until the ball coupling engages into a securely
engaged and locked in a vertical position and then engages
again under the bumper.
When the ball coupling is extended: pull and hold the button
X
in the tailgate until the ball coupling engages underneath the
bumper.
If the ball coupling still does not unlock:
Consult a qualified specialist workshop.
X