Mercedes-Benz M-Class Owner's Manual page 233

Towing a trailer
230
Vehicles with the AIRMATIC package
Make sure that the transmission is in posi-
X
tion P.
Engage the electric parking brake.
X
Start the engine.
X
Close the doors and tailgate.
X
Secure the trailer against rolling away.
X
Remove the trailer cable and decouple the
X
trailer.
Switch off the engine.
X
Folding in the ball coupling
i
Fold the ball coupling back in if you are
not using the trailer tow hitch.
Make sure that the vehicle is stationary and
X
the trailer cables are disconnected.
Place the protective cap on the ball cou-
X
pling.
Open the tailgate.
X
Pull the release knob : until the ball cou-
X
pling unlocks.
The ball coupling folds down from under the
rear bumper. The indicator lamp on the
release knob flashes.
Press the ball coupling in the direction of
X
the arrow until it engages audibly behind
the bumper.
The indicator lamp on the release knob
goes out and the message in the multifunc-
tion display disappears.
Trailer power supply
When it leaves the factory, your vehicle's
trailer socket is equipped with a permanent
power supply and a power supply that is
switched on via the ignition lock.
The permanent power supply is supplied via
trailer socket pin 9.
The power supply that is switched on via the
ignition lock is supplied via trailer socket pin
10.
! You can connect consumers with a power
rating of up to 240 W to the permanent
power supply and up to 180 W to the power
supply that is switched on via the ignition
lock.
You must not charge a trailer battery using
the power supply.
The trailer's permanent power supply is
switched off in the event of low vehicle supply
voltage and after six hours at the latest.
You can obtain further information about
installing the trailer electrics from a qualified
specialist workshop, e.g. a Mercedes-Benz
Service Centre.