tow MERCEDES-BENZ GL 2012 Owner's Guide

Once highway level has been reached, all
indicator lamps = go out. You will see a
message in the multifunction display, for
example:
If you have not previously selected the off-
road menu ( Y page 222) in the on-board
computer, the message disappears after
about five seconds.
The vehicle automatically adjusts to highway
level when you drive faster than
60 mph(115 km/h). Depending on the ADS
setting ( Y page 195), the vehicle is lowered
to high-speed level at high speeds.
i If a trailer is being towed, the vehicle is
not lowered to high-speed level.
ADS (Adaptive Damping System)
ADS is continuously electronically-controlled.
It adapts the damping characteristics to suit
the current operating conditions. The
damping is controlled for each wheel
individually. This improves driving safety and
tire comfort.
This depends on:
R your driving style
R the road surface conditions
R the ADS setting
R the vehicle level setting
Your selection remains stored even if you
remove the SmartKey from the ignition lock.
Vehicles without extended Off-Road Pro
engineering package
Vehicles with extended Off-Road Pro engineering
package
You can choose between the following ADS
settings:
R AUTO for normal driving situations;
indicator lamps ; and = are off.
R SPORT for sporty driving; indicator
lamp ; is on. In comparison with AUTO or
COMF , the vehicle is lowered by
0.6 in(15 mm).
R COMF for a more comfortable ride;
indicator lamp = is on.
XStart the engine.XPress button : repeatedly until the
desired setting is selected.Driving systems195Driving and parkingZ

Deactivating/activating PARKTRONIC
Vehicles without the Enhanced Off-Road Pro
Engineering Package
:To deactivate/activate PARKTRONIC;Indicator lamp
Vehicles with the Enhanced Off-Road Pro
Engineering Package
:To deactivate/activate PARKTRONIC;Indicator lamp
If indicator lamp ; lights up, PARKTRONIC is
deactivated.
i PARKTRONIC is automatically activated
when you turn the SmartKey to position 2
in the ignition lock.
Trailer towing
PARKTRONIC is deactivated for the rear area
when you establish an electrical connection
between your vehicle and a trailer.
! Fold in the ball coupling if the trailer tow
hitch is not required. PARKTRONIC
measures the minimum detection range to
an obstacle from the bumper, not the ball
coupling.
! Vehicles with an exterior spare wheel:
Remove the detachable ball coupling if the
trailer tow hitch is not required.
PARKTRONIC measures the minimum
detection range to an obstacle from the
bumper, not the ball coupling.198Driving systemsDriving and parking

GWARNING
The rear view camera is only an aid and may
display obstacles
R from a distorted perspective
R inaccurately
R may not display obstacles at all
The rear view camera does not relieve you of
the responsibility to be cautious. Take care
and pay careful attention. The rear view
camera may not show objects which are
R very close to the rear bumper
R under the rear bumper
R above the tailgate handle
You are responsible for safety at all times and
must continue to pay attention to the
immediate surroundings when parking and
maneuvering. This includes the area behind,
in front of, and beside the vehicle. Otherwise
you could endanger yourself and/or others.
GWARNING
The rear view camera will not function or will
not fully function if:
R the tailgate is open
R it is raining or snowing strongly or if it is
foggy
R it is night or if you are parking/
maneuvering your vehicle in a very dark
area
R a very bright white light is affecting the
camera
R the immediate vicinity is illuminated with
fluorescent light (the display can flicker)
R temperature changes abruptly, for example
if you drive out of the cold into a heated
garage (condensation on the lens)
R the camera lens is dirty or covered
R the rear of your vehicle is damaged
In this case, have the position and the
setting of the camera checked at a
specialist workshop. Mercedes-Benz
recommends that you consult a Mercedes-
Benz Center for this purpose.
Do not use the rear view camera in these
situations. You could otherwise injure
yourself and other people and/or cause
damage - including damage to your vehicle -
while parking/maneuvering.
Activating the rear view cameraXMake sure that the SmartKey is in position
2 in the ignition lock.XMake sure that the "rear view camera"
function is selected in COMAND (see the
separate operating instructions for
COMAND).XEngage reverse gear.
The area behind the vehicle is shown in the
COMAND display with guide lines.
Guide lines in the COMAND display
GWARNING
Use of rear view camera can be dangerous if
you are color-blind or have impaired color
vision.
Only use rear view camera if you can see and
distinguish all colored guidelines shown by
rear view camera on the COMAND system
display.
GWARNING
Please note that objects that do not touch the
ground may appear to be further away than
they actually are, for example:
R the bumper of a vehicle parked behind you
R the trailer drawbar
R the ball coupling of a trailer tow hitch
R the rear end of a truck
R a slanted post
In such cases, you should not use the guide
lines to judge the distance. You may misjudge
the distance, which increases the risk of
impacting the objects.
Even if the object you approach is directly on
the ground, do not approach the object any
closer than the red guide line.
200Driving systemsDriving and parking

Information in the COMAND display (example)
Guide lines ; and = show the approximate
distance to the rear area. Yellow guide
line ; indicates a distance of approximately
3 ft (1 m) and red guide line = indicates a
distance of approximately 10 in (0.25 m). The
distances only apply to objects that are at
ground level. Blue guide lines : depict the
width required for the vehicle. They are used
to align the vehicle with the edge of the road,
e.g. the curb.
Blind Spot Assist
Important safety notes
Blind Spot Assist uses a radar sensor system
to monitor the areas on both sides of your
vehicle. It begins to work at speeds of
approximately 20 mph (30 km/h). A warning
display in the exterior mirrors draws your
attention to detected vehicles in the
monitored area. If you then indicate a turn
towards that side before changing lanes, you
will also receive visual and audible collision
warnings. The Blind Spot Assist monitoring
system uses sensors in the rear bumper.
GWARNING
Blind Spot Assist is only an aid designed to
assist driving. It may fail to detect some
vehicles and is no substitute for attentive
driving.
Blind Spot Assist cannot detect road and
traffic conditions. It may fail to detect narrow
vehicles, such as motorcycles or bicycles, or
may only detect them too late.
Monitoring may be affected by dirty sensors,
strong spray or poor visibility caused by snow,
rain or mist, for example. In this case, vehicles
are detected late or not at all.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
i USA only:
This device has been approved by the FCC
as a “Vehicular Radar System”. The radar
sensor is intended for use in an automotive
radar system only. Removal, tampering, or
altering of the device will void any
warranties, and is not permitted by the
FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this
device could void the user’s authority to
operate the equipment.
For Blind Spot Assist to assist you when
driving, the radar sensor system must be
activated ( Y page 227) and operational.
Monitoring range of the sensors
Blind Spot Assist monitors the area shown in
the figure up to 10 ft (3 m) behind and
immediately adjacent to your vehicle.
Driving systems201Driving and parkingZ

side. When you are passing another vehicle,
the warning is emitted only if the difference
in speed is less than 7 mph (12 km/h).
The yellow indicator lamp goes out if the
reverse gear is engaged. In this event, Blind
Spot Assist is no longer active.
The brightness of the indicator/warning
lamps is adjusted automatically according to
the ambient light.GWARNING
Blind Spot Assist is not active at speeds under
approximately 20 mph (30 km/h). The
indicator lamps in the exterior mirrors are
yellow. Vehicles in the monitoring range are
then not indicated.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
Collision warning
If a vehicle is detected in the monitoring range
of Blind Spot Assist and you switch on the turn
signal, a double warning tone sounds. Red
warning lamp : flashes. If the turn signal
remains on, detected vehicles are indicated
by the flashing of red warning lamp :. There
are no further warning tones.
Switching on Blind Spot Assist
XMake sure that the radar sensor system
( Y page 227) and Blind Spot Assist
( Y page 228) are activated in the on-board
computer.XTurn the SmartKey to position 2 in the
ignition lock.
Warning lamps : light up red in the
exterior mirrors for approximately 1.5
seconds and then turn yellow.
Trailer towing
When you attach a trailer, make sure you have
correctly established the electrical
connection. This can be accomplished by
checking the trailer lighting. In this event,
Blind Spot Assist is deactivated. The indicator
lamp in the exterior mirrors lights up yellow
and the Blind Spot Assist Currently
Unavailable See Operator's Manual
message appears in the multifunction
display.
i You can deactivate the indicator lamps in
the exterior mirrors.
To do so, switch off Blind Spot Assist when:
R the SmartKey is in position 2 in the
ignition lock.
R the engine is not running.
R the electrical connection to the trailer
has been established.
Off-road driving systems
4MATIC (permanent four-wheel drive)
4MATIC ensures that all four wheels are
permanently driven. Together with ESP ®
and
4ETS , it improves the traction of your vehicle
whenever a drive wheel spins due to
insufficient grip.
GWARNING
If a drive wheel is spinning due to insufficient
traction:
R While driving off, apply as little throttle as
possible.
R While driving, ease up on the accelerator
pedal.
R Adapt your speed and driving style to the
prevailing road conditions.
Failure to observe these guidelines could
cause the vehicle to skid.
The 4MATIC cannot prevent accidents
resulting from excessive speed.
! Never tow the vehicle with one axle
raised. This may damage the transfer case.
Damage of this sort is not covered by the
Mercedes-Benz Limited Warranty. All
wheels must remain either on the ground
Off-road driving systems203Driving and parkingZ

or be fully raised. Observe the instructions
for towing the vehicle with all wheels in full
contact with the ground.
i In wintry driving conditions, the maximum
effect of 4MATIC can only be achieved if
you use winter tires ( M+S tires), with snow
chains if necessary.
! When testing the parking brake, operate
the vehicle only briefly (for a maximum of
ten seconds) on a brake test dynamometer.
When doing this, turn the key to position
0 or 1 in the ignition. Failure to do this can
cause damage to the drive train or the
brake system.
! Function or performance tests may only
be performed on a 2-axle dynamometer. If
you wish to operate the vehicle on such a
dynamometer, please consult an
authorized Mercedes-Benz Center
beforehand. You could otherwise damage
the drive train or the brake system.
For information about driving off-road, see
( Y page 174).
DSR (Downhill Speed Regulation)
Important safety notes
DSR is an aid to assist you when driving
downhill. It keeps the speed of travel at the
speed selected on the on-board computer.
The steeper the downhill gradient, the greater
the DSR braking effect on the vehicle. When
driving on flat stretches of road or on an uphill
gradient, the DSR braking effect is minimal or
non-existent.
The set speed is set to 4 mph (6 km/h) at the
factory; this can be adjusted using the on-
board computer ( Y page 228).
GWARNING
Downhill Speed Regulation (DSR) is a
convenience system designed to assist the
driver during vehicle operation. The system
setting must be appropriate to the
topographical and weather conditions
encountered, which can change quickly. The
driver is responsible for the vehicle speed and
for safe brake operation at all times.
Depending on the programmed speed, actual
vehicle speed and gradient, switching on DSR
while driving can cause the vehicle to slow
down rapidly, and you may hear a sound,
caused by the activation of the vehicle's brake
system through DSR. Sudden and unexpected
deceleration can result in loss of vehicle
control, causing an accident and/or serious
personal injury to you and others. Do not
switch on DSR in a situation where rapid
deceleration could result in a loss of vehicle
control.
DSR controls the set speed when it is active
and the automatic transmission is in the D,
R or N position. You can drive at a higher or
a lower speed than that set on the on-board
computer at any time by accelerating or
braking.GWARNING
If you depress the accelerator pedal with DSR
activated, the vehicle can drive faster than the
programmed set speed. You should therefore
drive downhill with particular caution as it
could lead to an accident and/or serious
injury to you or others. Keep in mind that as
soon as you remove your foot from the
accelerator pedal with DSR switched on, DSR
will start regulating the vehicle's speed
including use of brakes if required. Depending
on the programmed set speed, actual vehicle
speed and gradient, DSR can cause the
vehicle to slow down rapidly. Sudden and
unexpected deceleration can result in loss of
vehicle control, causing an accident and/or
serious personal injury to you and others.
For information about driving off-road, see
( Y page 174).
204Off-road driving systemsDriving and parking

lost and steering would no longer be possible.
The differential locks must therefore only be
activated off-road and only if activating the
other driving systems (4ETS, ESP ®
and LOW
Range off-road gear) is no longer sufficient.
Engaging the differential locks
! Pull away slowly when the differential
locks are activated.
Function or performance tests may only be
performed on a 2-axle dynamometer. If you
wish to operate the vehicle on such a
dynamometer, please consult an
authorized Mercedes-Benz Center
beforehand. You could otherwise damage
the drive train or the brake system.
Automatic mode
Use automatic mode ; for all driving
situations, including driving off-road or when
fording.
In automatic mode, the differential locks are
engaged and disengaged according to driving
requirements. This guarantees sufficient
traction for most driving situations with
unrestricted vehicle steerability.
XStart the engine.
The differential locks are in automatic
mode. The indicator lamp in selector
wheel : lights up above symbol for
automatic mode ;.Engaging manuallyGWARNING
Never drive on a paved surface with the center
and rear axle differential locks manually
engaged. Ability to steer the vehicle is greatly
reduced when the differential locks are
manually engaged, increasing the risk of an
accident.
For safety reasons, the locks are
automatically released at a vehicle speed
above 31 mph (50 km/h). Nevertheless, you
should only manually lock the differential if
absolutely necessary because engaged locks
will restrict the vehicle drivetrain while
cornering and cause the vehicle to chatter.
This could cause you to lose control of the
vehicle and cause an accident.
! The differential locks must not be
activated when the vehicle is being towed
or while the wheels are spinning.
Only engage the differential locks manually if
traction in automatic mode is insufficient.
The differential locks can be activated
manually up to a speed of 19 mph
(30 km/h).
XStart the engine.XTurn selector wheel : to desired position
= or ?.
The indicator lamp in selector wheel :
lights up at the corresponding symbol.
The engaged differential appears in the
multifunction display:
AThe differential lock for the transfer case
is locked.
If you have not previously selected the off-
road menu ( Y page 222) in the on-board
Off-road driving systems209Driving and parkingZ

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