2012 MERCEDES-BENZ GL-Class change wheel

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

surface is free of ice. The road may still be icy,
especially in wooded areas or on bridges.
Changes in the outside temperature are
displayed after a short delay.
Speedometer with segments
The segments in the speedometer indicate
which speed range is available.
DISTRONIC ( Y page 182) activated:
One or two segments in the set speed range
light up.
DISTRONIC detects a vehicle in front:
The segments between the speed of the
vehicle in front and the stored speed light up.
Operating the on-board computer
The on-board computer is activated as soon
as you turn the SmartKey to position 1 in the
ignition lock.
You can control the multifunction display and
the settings in the on-board computer using
the buttons on the multifunction steering
wheel.
:Multifunction display;~
Rejects or ends a call
Exits phone book/redial memory
6
Makes or accepts a call
Switches to the redial memory
WX
Selects submenus in the Settings
menu
Changes values
Adjusts the volume
?
Switches on the Voice Control
System; see the separate operating
instructions=VU
Selects a menu: scrolls back and
forth
A
Switches off the Voice Control
System; see the separate operating
instructions&*
Press briefly:
Scrolls back and forth within a menu
In the Audio menu: selects a stored
station, an audio track or a video
scene
In the Telephone menu: switches to
the phone book and selects a name
or a telephone number&*
Press and hold:
In the Audio menu: selects the
previous/next station or selects an
audio track using rapid scrolling
In the Telephone menu: starts rapid
scrolling through the phone bookDisplays and operation217On-board computer and displaysZ

XPress the V or U button on the
steering wheel to select the standard
display.XPress the & or * button to select
digital speedometer or the outside
temperature.
Digital speedometer
Outside temperature
Audio menu
Selecting a radio station
i SIRIUS XM satellite radio acts like a
normal radio.
For more information on satellite radio
operation, see the separate operating
instructions.
You can only change the waveband and store
new stations using COMAND.
XSwitch on COMAND and select Radio (see
the separate operating instructions).XPress the V or U button on the
steering wheel to select the Audio menu.:Waveband 25;Current stationXTo select a stored station:
briefly press
the & or * button.XTo select a station from the station
list: press and briefly hold the & or
* button.XTo select a station using station
search 26
: press and briefly hold the &
or * button.
Operating audio player or audio media
Audio data from various audio devices or
media can be played, depending on the
equipment installed in the vehicle.
XSwitch on COMAND and select the audio
device or medium (see the separate
operating instructions).XPress the V or U button on the
steering wheel to select the Audio menu.
CD changer display (example)
:Current CD;Current track25
If current station ; has been stored, the memory position will also be displayed.
26 Only if no station list is received.Menus and submenus221On-board computer and displaysZ

XTo select the next/previous track:
briefly press the & or * button.XTo select a track from the track list
(rapid scrolling): press and briefly hold the
& or * button.
The current track will not be displayed in
audio AUX mode ( Auxiliary audio mode:
external audio source connected).
Operating video DVD
XSwitch on COMAND and select video DVD
(see the separate operating instructions).XPress the V or U button on the
steering wheel to select the Audio menu.
DVD changer display (example)
:Current DVD (for DVD changer);Current sceneXPress the & or * button to select a
scene.
Navigation system menu
Displaying navigation instructions
In the Navigation menu: the instructions
from the navigation system appear in the
multifunction display. For more information,
see the separate operating instructions.
XSwitch on COMAND (see the separate
operating instructions).XPress the V or U button on the
steering wheel to select the Navigation
menu.Route guidance inactive
The direction of travel appears in the
multifunction display. If the name of the
street is part of the navigation system data,
this will also be displayed.
Route guidance active
The multifunction display shows navigation
instructions, for example:
Off-road menu
Depending on your vehicle's optional
equipment, you can set the following current
settings to be shown in the Off-road menu:
R Level control ( Y page 189)
R compass ( Y page 296)
R differential locks ( Y page 208)
i Large buildings, power cables or powerful
transmission masts as well as metallic
objects on or in the vehicle may interfere
with the compass display.
XPress V or U on the steering wheel
to select the Offroad menu.222Menus and submenusOn-board computer and displays

TiresGWARNING
Do not drive with a flat tire. A flat tire affects the ability to steer or brake the vehicle. You may
lose control of the vehicle. Continued driving with a flat tire will cause excessive heat build-up
and possibly a fire.
GWARNING
Follow recommended tire inflation pressures.
Do not underinflate tires. Underinflated tires wear excessively and/or unevenly, adversely affect
handling and fuel economy, and are more likely to fail from being overheated.
Do not overinflate tires. Overinflated tires can adversely affect handling and ride comfort, wear
unevenly, increase stopping distance, and result in sudden deflation (blowout) because they are
more likely to become punctured or damaged by road debris, potholes etc.
Display messagesPossible causes/consequences and M SolutionsTire Pressure
Check TiresGRisk of accident
The tire pressure loss warning system has detected a significant
loss in pressure.
XStop the vehicle without making any sudden steering or braking
maneuvers. Pay attention to the traffic conditions as you do so.XCheck the tires and, if necessary, change the wheel
( Y page 362).XCheck the tire pressures and, if necessary, set to the correct
tire pressure.XRestart the tire pressure loss warning system when the tire
pressure is correct ( Y page 345).Check tires,
then restart Run
Flat IndicatorThe tire pressure loss warning system generated a display
message and has not been restarted since.XSet the correct tire pressure in all four tires.XRestart the tire pressure loss warning system ( Y page 345).Run Flat Indicator
InoperativeThe tire pressure loss warning system is defective.XVisit a qualified specialist workshop.Tire pressure
displayed after
driving for a few
minutesThe tire pressure monitor is measuring the tire pressure.XDrive on.
The tire pressures appear in the multifunction display after you
have been driving for a few minutes.Tire Pressure
Monitor
InoperativeThe tire pressure monitor is defective.XVisit a qualified specialist workshop.252Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsTire Pressure
Monitor
Inoperative No
Wheel SensorsThe wheels mounted do not have a suitable tire pressure sensor.
The tire pressure monitor is deactivated.XMount wheels with suitable tire pressure sensors.
The tire pressure monitor is activated automatically after driving
for a few minutes.Check
Tire(s)GRisk of accident
The tire pressure in one or more tires has dropped significantly.
The wheel position is displayed in the multifunction display.
XStop the vehicle without making any sudden steering or braking
maneuvers. Pay attention to the traffic conditions as you do so.XCorrect the tire pressure ( Y page 347).XIf necessary, change a wheel ( Y page 362).Caution:
Tire DefectGRisk of accident
The tire pressure in one or more tires has dropped suddenly. The
wheel position is displayed in the multifunction display.
XStop the vehicle without making any sudden steering or braking
maneuvers. Pay attention to the traffic conditions as you do so.XIf necessary, change a wheel ( Y page 362).Tire Pressure(s)
Please CorrectThe tire pressure is too low in at least one of the tires or the tire
pressure difference between the wheels is too great.XCheck the tire pressures at the next opportunity. If necessary,
correct the tire pressure ( Y page 347).XRestart the tire pressure monitor ( Y page 349).Tire Pressure
Monitor
Wheel Sensor
MissingThere is no signal from the tire pressure sensor of one or several
wheels. The pressure of the affected tire is not displayed in the
multifunction display.XHave the defective tire pressure sensor replaced at a qualified
specialist workshop.Tire Pressure
Monitor
Currently
UnavailableDue to a source of radio interference, no signals can be received
from the wheel sensors. The tire pressure monitor is temporarily
malfunctioning.XDrive on.
The tire pressure monitor restarts automatically as soon as the
problem has been solved.Display messages253On-board computer and displaysZ