2012 MERCEDES-BENZ GL-Class Towing

computer, the message disappears after
about five seconds.
The differential locks are not controlled
automatically. The steerability of the vehicle
is restricted considerably. Drive carefully and
accelerate gently for optimum traction.
! If the differential locks are activated
manually, the wheels scuff on the road
when cornering since the rotation
difference between the wheels is no longer
balanced out.
You can switch back to automatic mode at
any time. For safety reasons, the differential
locks are deactivated automatically at speeds
over 31 mph (50 km/h). If you stop the
vehicle and switch off the ignition for longer
than ten seconds, the differential locks
switch back to automatic mode.
Message in the multifunction display
Diff. lock system overheated.
Wait briefly.
The differential lock system has overheated
and briefly disengaged.XContinue driving.
The differential locks cool off and are soon
available once again.
Trailer towing
Notes on towing a trailer
Important safety notes
GWARNING
When towing a trailer, incorrect equipment
and driving style could cause you to lose
control of the vehicle.
Towing incorrectly or not observing this
Operator's Manual could lead to damage to
the vehicle and/or serious injuries. Observe
the following guidelines to ensure safe trailer
towing.
Contact a Mercedes-Benz Center if you need
further explanation of the information
contained in this Operator's Manual.
General information
R Only install an approved trailer coupling on
your vehicle.
Further information on availability and on
installation is available from any authorized
Mercedes-Benz Center.
R The bumpers of your vehicle are not
suitable for installing detachable trailer
couplings.
R Do not install hired trailer couplings or
other detachable trailer couplings on the
bumpers of your vehicle.
R To reduce the risk of damage to the ball
coupling, remove it from the ball coupling
recess when not in use.
Coupling up a trailer
GWARNING
While you are coupling or decoupling a trailer,
make sure nobody locks or unlocks the
vehicle and/or opens or closes doors or the
tailgate.
The vehicle's level could change and you
could endanger yourself and/or others as a
result.
Make sure that you do not operate the ADS
button or the vehicle level control system
when coupling/decoupling the trailer.
Observe the maximum permissible trailer
dimensions (width and length).
Most federal states and all Canadian
provinces require by law:
R safety chains between the towing vehicle
and the trailer. The chains should be cross-
wound under the trailer drawbar. They must
be fastened to the vehicle's trailer
coupling, not to the bumper or the axle.
210Trailer towingDriving and parking

Allow for enough play in the chains to
facilitate turning tight corners.
R a separate brake system for certain types
of trailer.
R a safety switch for braked trailers. Check
the specific legal requirements applicable
to your federal state.
If the trailer detaches from the towing
vehicle, the safety switch applies the
trailer's brakes.
! 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.
i The vehicle's wiring harness features a
line to the brake indicator lamp.XMake sure that the automatic transmission
is set to position P.XApply the vehicle's parking brake.XStart the engine.XSelect highway level.XVehicles with the adaptive damping
system: set ADS to AUTO or COMF .XSwitch off the engine.XClose all doors and the tailgate.XCouple up the trailer.XEstablish all electrical connections.
i
Vehicles with the AIRMATIC package:
with a trailer attached, the vehicle will
always remain at highway level. When
coupling up a trailer, please observe the
following:
R if highway level has not been set
manually, the vehicle will automatically
sink to highway level as soon as it
reaches a speed of 5 mph (8 km/h).
R high-speed level is not available.
These restrictions apply to all accessories
powered through a connection to the trailer
power socket of your vehicle, e.g. a bicycle
carrier.
Towing a trailer
There are numerous legal requirements
concerning the towing of a trailer, e.g. speed
restrictions. Make sure that your vehicle/
trailer combination complies with the local
requirements not only in your area of
residence but also at any location to which
you are traveling. The police and local
authorities can provide reliable information.
Please observe the following when towing a
trailer:
R To acquaint yourself with driving with a
trailer and with the resulting changes to
handling, you should practice cornering,
stopping and reversing in a traffic-free
location.
R Before driving, check:
- the trailer tow hitch
- the safety switch for braked trailers
- the safety chains
- the electrical connections
- the lights
- the wheels
R Adjust the exterior mirrors to provide an
unobstructed view of the rear section of the
trailer.
R If the trailer features electronically
controlled brakes, pull away the vehicle/
trailer combination carefully, manually
brake using the brake controller, and check
the brakes for correct function.
R Secure any objects on the trailer to prevent
the cargo from slipping when the vehicle is
in motion.
R If you couple up a trailer, regularly check
the cargo for secure fastening and make
sure that the trailer lamps and (if
applicable) the trailer brakes are
functioning correctly.
R Bear in mind that the handling will be less
stable when towing a trailer than when
Trailer towing211Driving and parkingZ

driving without one. Avoid sudden steering
movements.
R The vehicle/trailer combination is heavier,
accelerates more slowly, has a decreased
gradient climbing capability and a longer
braking distance.
It is more susceptible to side winds and
requires more careful steering.
R If possible, avoid abrupt braking. Depress
the brake pedal moderately at first, so that
the trailer can activate its own brakes. Then
increase the pressure on the brake pedal.
R If the automatic transmission continues to
shift back and forth between two gears
when driving up or downhill, restrict the
shift range. Select shift range 4, 3, 2, or 1.
A lower gear and lower speed reduce the
risk of engine failure.
R On long and steep gradients that are
difficult to drive down in shift range 1,
switch to the off-road drive program or
engage the LOW RANGE off-road gear.
R When driving downhill, shift to a lower gear
to utilize the engine's braking effect.
Avoid continuous brake application as this
may overheat the vehicle brakes and, if
installed, the trailer brakes.
R If the coolant temperature increases
dramatically while the air-conditioning
system is switched on, switch off the air-
conditioning system.
Coolant heat can additionally be dissipated
by opening the windows and by setting the
blower fan and the interior temperature to
maximum.
R When overtaking, pay particular attention
to the extended length of your vehicle/
trailer combination.
Due to the length of your vehicle/trailer
combination, you will have to travel an
additional distance beyond the vehicle you
are overtaking before returning to the
previous lane.Decoupling a trailerGWARNING
While you are coupling or decoupling a trailer,
make sure nobody locks or unlocks the
vehicle and/or opens or closes doors or the
tailgate.
The vehicle's level could change and you
could endanger yourself and/or others as a
result.
Make sure that you do not operate the ADS
button or the vehicle level control system
when coupling/decoupling the trailer.
XMake sure that the automatic transmission
is set to position P.XApply the vehicle's parking brake.XStart the engine.XClose all doors and the tailgate.XApply the trailer's parking brake.GWARNING
As soon as you disconnect the electrical
connection between the trailer and the
vehicle, the vehicle will lower. To help avoid
personal injury, make sure no one is near the
wheel housing or underneath the vehicle
before the electrical connection is
disconnected.
When you decouple the trailer, the vehicle is
temporarily raised because the springs are
relieved of load. Be especially careful during
this process, as you could otherwise injure
yourself and/or others. Make sure that any
persons remaining in the vehicle do not press
the switches for vehicle level control or the
ADS.
XRemove the trailer cable and decouple the
trailer.XSwitch off the engine.212Trailer towingDriving and parking

Permissible trailer loads and drawbar
noseweights
Weight specifications
The Gross Trailer Weight (GTW) is the
combined weight of the trailer together with
the cargo and equipment loaded on the
trailer. Permissible gross weight: 7500 lb
(3402 kg).
The permissible Trailer drawbar Weight
Rating (TWR) is the maximum weight
permitted on the trailer drawbar: 600 lb
(272 kg) limit for Mercedes-Benz-approved
trailer couplings.
Loading a trailer
R When loading a trailer, please note that
neither the permissible gross trailer weight
nor the permissible Gross Vehicle Weight
Rating (GVWR) may be exceeded. The
permissible Gross Vehicle Weight Rating
(GVWR) is specified on the type plate
located on the B-pillar on the driver's side
of your vehicle.
You can find the maximum permissible
values on the type plates of your vehicle
and the trailer. Always observe the lowest
respective value when determining the
maximum weight with which you can load
the vehicle and the trailer.
R The drawbar noseweight acting on the ball
coupling has to be added to the rear axle
weight in order to prevent the permissible
Gross Axle Weight Rating (GAWR) from
being exceeded. The permissible Gross
Vehicle Weight Rating (GVWR) is specified
on the type plate located on the B-pillar on
the driver's side of your vehicle.
i Mercedes-Benz recommends loading the
trailer so that the drawbar noseweight
remains between 8% and 15% of the
permissible gross trailer weight.
i The weight of additional accessories,
passengers, and cargo reduces the
permissible trailer load and drawbar
noseweight for your vehicle.
Checking the vehicle and trailer weight
R To check that the weights of the towing
vehicle and the trailer comply with the
maximum permissible values, have the
vehicle/trailer combination (including the
driver, passengers, and cargo with a fully
laden trailer) weighed on a calibrated
weighbridge.
R Check the gross axle weight rating of the
front and rear axle, the Gross Trailer Weight
(GTW), and the drawbar noseweight.
Trailer power supply
The trailer power socket of your vehicle is
designed for connecting the 7-pin connector
supplied as part of the Mercedes-Benz-
approved trailer coupling.
i Depending on your trailer, you may need
an adapter to connect your trailer to the
vehicle.
Further information is available from any
authorized Mercedes-Benz Center.
Trailer towing213Driving and parkingZ

Driving systemsDisplay messagesPossible causes/consequences and M Solutions°
Level Selection
Not PermittedYou cannot change the vehicle level, because:
R you are exceeding the permissible speed for the selected
vehicle level.
R you are towing a trailer.
R the trailer-coupling socket is being used, e.g. for a bicycle rack.XDrive more slowly and then select the desired vehicle level again
( Y page 189).XObserve the notes on towing a trailer ( Y page 210).°
Compressor Cooling
DownYou have selected a higher vehicle level. The compressor first
needs to cool down because of frequent level changes.XDrive in a manner appropriate for the current vehicle level.XMake sure that there is sufficient ground clearance.XAllow the compressor to cool down.
When the compressor has cooled down, the display message
disappears. The vehicle then continues rising to the selected
level.°
MalfunctionLevel control is defective.XDo not drive faster than 50 mph (80 km/h).XMake sure that there is sufficient ground clearance.XHave the vehicle checked at a qualified specialist workshop.Æ
Reduce speed to
under 12 MPHGRisk of accident
You are exceeding the speed permissible for the selected off-road
level.
XAdjust your driving style to the altered handling characteristics.XOnly make slight steering movements and avoid fast steering
movements.XDo not drive faster than 12 mph (20 km/h).°
Rising Max. 12 MPHThe vehicle is being adjusted to off-road level 3. The display
message informs you of the maximum speed permissible for off-
road level 3.XDo not drive faster than 12 mph (20 km/h).°
Max. 12 MPHYou are driving in off-road level 3. The display message informs
you of the maximum speed permissible for off-road level 3.XDo not drive faster than 12 mph (20 km/h).248Display messagesOn-board computer and displays

Useful information ............................268
Loading guidelines ............................268
Stowage areas .................................. 268
Features ............................................. 282267Stowing and features

Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note that your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Please read the information on qualified
specialist workshops ( Y page 24).
Loading guidelines
GWARNING
Always fasten items being carried as securely
as possible. Use cargo tie-down rings and
fastening materials appropriate for the weight
and size of the load.
In an accident, during hard braking or sudden
maneuvers, loose items will be thrown around
inside the vehicle. This can cause injury to
vehicle occupants unless the items are
securely fastened in the vehicle.
To help avoid personal injury during a collision
or sudden maneuver, exercise care when
transporting cargo. Do not pile luggage or
cargo higher than the seat backrests.
The cargo compartment is the preferred place
to carry objects. Always use cargo tie-down
rings, and if so equipped, always use the cargo
net when transporting cargo.
Never drive a vehicle with the tailgate open.
Deadly carbon monoxide (CO) gases may
enter vehicle interior resulting in
unconsciousness and death.
The gross vehicle weight (GVW) is the vehicle
weight including fuel, vehicle tool kit, spare
wheel, installed accessories, vehicle
occupants and luggage/cargo.
The gross load limit and the gross vehicle
weight rating (GVWR) for your vehicle must
never be exceeded. The gross load limit and
the GVWR are specified on the vehicle
identification plate on the B-pillar of the
driver's door ( Y page 349).
The load must also be distributed so that the
weight on each axle never exceeds the gross
axle weight rating (GAWR) for the front and
rear axles. The specifications for GVWR and
GAWR are on the vehicle identification plate
on the B-pillar of the driver's door
( Y page 349).
Further information can be found in the
"Loading the vehicle" section ( Y page 349).
The handling characteristics of a laden
vehicle are dependent on the distribution of
the load within the vehicle. For this reason,
you should observe the following notes when
transporting a load:
R position heavy loads as far forwards as
possible and as low down in the cargo
compartment as possible.
R the load must not protrude above the upper
edge of the seat backrests.
R always place the load against the rear or
front seat backrests. Make sure that the
seat backrests are securely locked into
place.
R hook in the cargo net when loading.
R always place the load behind unoccupied
seats if possible.
R secure the load with sufficiently strong and
wear-resistant tie down. pad sharp edges
for protection.
Stowage areas
Stowage compartments
Important safety notes
GWARNING
To help avoid personal injury during a collision
or sudden maneuver, exercise care when
storing objects in the vehicle. Put luggage or
cargo in the cargo compartment if possible.
268Stowage areasStowing and features

Do not pile luggage or cargo higher than the
seat backrests.
If so equipped, always use the cargo net when
transporting cargo. The cargo net cannot
secure hard or heavy objects.
Parcel nets cannot secure hard or heavy
objects.
Keep compartment lids closed. This will help
to prevent stored objects from being thrown
about and injuring vehicle occupants during
R braking
R vehicle maneuvers
R an accident
Stowage compartments in the front
Glove box
XTo open: pull handle : and open glove box
flap ;.XTo close: fold glove box flap ; upwards
until it engages.
The glove box can only be locked and
unlocked using the mechanical key.
1Glove box unlocked2Glove box locked
Stowage compartment in the center
console
XTo open: briefly press marking ;.XTo close: push stowage compartment :
in the direction of the arrow until it
engages.
Stowage compartment under the armrest
i The º (Y page 290) Roadside
Assistance call button and
E (Y page 290) MB Info call button are
located in the stowage compartment under
the armrest.
Stowage areas269Stowing and featuresZ