2012 MERCEDES-BENZ GL-Class traction control

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

ProblemPossible causes/consequences and M Solutions!
The yellow ABS warning
lamp is lit while the
engine is running. A
warning tone also
sounds.GRisk of accident
EBD is faulty. Therefore, ABS, BAS, PRE-SAFE ®
, hill start assist and
ESP ®
trailer stabilization, for example, are also not available due
to a malfunction.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
XObserve the additional display messages in the multifunction
display.XDrive on carefully.XVisit a qualified specialist workshop.$ (USA only)
J (Canada only)
֌!
The red brake warning
lamp, the yellow ESP ®
and ESP ®
OFF warning
lamps and the yellow
ABS warning lamp are
lit while the engine is
running.GRisk of accident
ABS and ESP ®
are faulty. As a result other systems, such as, BAS,
EBD, PRE-SAFE ®
, hill start assist and ESP ®
trailer stabilization...,
may also be unavailable due to a malfunction.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
XObserve the additional display messages in the multifunction
display.XDrive on carefully.XVisit a qualified specialist workshop.÷
The yellow ESP ®
warning lamp flashes
while the vehicle is in
motion.GRisk of accident
ESP ®
or traction control has intervened because there is a risk of
skidding or at least one wheel has started to spin.
Cruise control or DISTRONIC is deactivated.
XOnly depress the accelerator pedal as far as necessary when
pulling away.XRelease the accelerator pedal while the vehicle is in motion.XAdapt your driving style to suit the road and weather conditions.XDo not deactivate ESP ®
.
For exceptions: ( Y page 69).Warning and indicator lamps in the instrument cluster261On-board computer and displaysZ

Notes on regularly inspecting wheels
and tiresGWARNING
Regularly check the tires for damage.
Damaged tires can cause tire inflation
pressure loss. As a result, you could lose
control of your vehicle.
Worn, old tires can cause accidents. If the tire
tread is worn to minimum tread depth, or if
the tires have sustained damage, replace
them.
R Regularly check the wheels and tires of
your vehicle for damage (e.g. cuts,
punctures, tears, bulges on tires and
deformation or cracks or severe corrosion
on wheels) at least once a month, as well
as after driving off-road or on rough roads.
Damaged wheels can cause a loss of tire
pressure.
R Regularly check the tire tread depth and
the condition of the tread across the whole
width of the tire (Y page 339). If necessary,
turn the front wheels to full lock in order to
inspect the inner side of the tire surface.
R All wheels must have a valve cap to protect
the valve against dirt and moisture. Do not
mount anything onto the valve (such as tire
pressure monitoring systems) other than
the standard valve cap or other valve caps
approved by Mercedes-Benz for your
vehicle.
R Regularly check the pressure of all the tires
including the emergency spare wheel or the
spare wheel, particularly prior to long trips,
and correct the pressure as necessary
( Y page 341).
Tire tread
GWARNING
Although the applicable federal motor vehicle
safety laws consider a tire to be worn when
the tread wear indicators (TWI) become
visible at approximately 1
/ 16 in (1.6 mm), we
recommend that you do not allow your tires
to wear down to that level. As tread depth
approaches 1
/ 8 in (3 mm), the adhesion
properties on a wet road are sharply reduced.
Depending upon the weather and/or road
surface (conditions), the tire traction varies
widely.
Do not use tires that are excessively worn as
the tire traction on wet road surfaces
decreases significantly when the tread depth
is less than 1
/ 8 inch (3 mm).
Tread wear indicators (TWI) are required by
law. Six indicators are positioned over the tire
tread. They are visible as soon as a tread
depth of approx. 1
/ 16 inch (1.6 mm) is
reached. If this is the case, the tire is so worn
that it must be replaced.
The recommended tread depth for summer
tires is at least 1
/ 8 inch (3 mm). The
recommended tread depth for winter tires is
at least 1
/ 6 inch (4 mm).
Bar marking
: for tread wear is integrated
into the tire tread.
Notes on selecting, mounting and
replacing tires
R Only mount tires and wheels of the same
type and make.
R Only mount tires of the correct size onto
the wheels.
R After mounting new tires, run them in at
moderate speeds for the first 60 miles
Operation339Wheels and tiresZ

Maximum tire load : is the maximum
permitted weight for which the tire is
approved.
Further information on tire loads
( Y page 355).
Uniform Tire Quality Grading
Standards
Overview of Tire Quality Grading
Standards
The Uniform Tire Quality Grading is a U.S.
Government requirement. Their purpose is to
provide drivers with consistent and reliable
information regarding tire performance. Tire
manufacturers are required to grade tires
using three performance factors: tread
wear :, tire traction ;, and temperature
resistance =. Although not a Government of
Canada requirement, all tires made for sale in
North America have these grades branded on
the sidewall.
i The actual values for tires are vehicle-
specific and may deviate from the values in
the illustration.
Where applicable, the tire grading
information can be found on the tire sidewall
between the tread shoulder and maximum
tire width.
For example:
Tread wearTractionTemperature200AAAAll passenger car tires must conform to the
statutory safety requirements in addition to
these grades.
Tread wear
The tread wear grade is a comparative rating
based on the wear rate of the tire when tested
under controlled conditions on a specified
U.S. government course. For example, a tire
graded 150 would wear one and one-half
times as well on the government course as a
tire graded 100.
The relative performance of tires depends
upon the actual conditions of their use,
however, and may depart significantly from
the norm, due to variations in driving habits,
service practices and differences in road
characteristics and climate conditions.
Traction
GWARNING
The traction grade assigned to this tire is
based on straight-ahead braking traction
tests, and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics.
The traction grades, from highest to lowest,
are AA, A, B, and C. Those grades represent
the tire's ability to stop on a wet surface as
measured under controlled conditions on
specified government test surfaces of asphalt
and concrete. A tire marked C may have poor
traction performance.
GWARNING
If ice has formed on the road, tire traction will
be substantially reduced. Under such weather
conditions, drive, steer and brake with
extreme caution.
The safe speed on a wet, snow covered or icy
road is always lower than on dry road
surfaces.
354Uniform Tire Quality Grading StandardsWheels and tires

For further information on the load bearing
index, see Load index ( Y page 358).
Speed index: speed index B specifies the
approved maximum speed of the tire.GWARNING
Even when permitted by law, never operate a
vehicle at speeds greater than the maximum
speed rating of the tires.
Exceeding the maximum speed for which tires
are rated can lead to sudden tire failure,
causing loss of vehicle control and possibly
resulting in an accident and/or serious
personal injury and possible death, for you
and for others.
Regardless of the speed index always observe
the speed limits. Drive carefully and adapt
your driving style to the traffic conditions.
Summer tiresIndexSpeed ratingQUp to 100 mph (160 km/h)RUp to 106 mph (170 km/h)SUp to 112 mph (180 km/h)TUp to 118 mph (190 km/h)HUp to 130 mph (210 km/h)VUp to 149 mph (240 km/h)WUp to 168 mph (270 km/h)YUp to 186 mph (300 km/h)ZR...YUp to 186 mph (300 km/h)ZR...(..Y)Above 186 mph (300 km/h)ZRAbove 149 mph (240 km/h)
R Optionally, tires with a maximum speed of
over 149 mph (240 km/h) may have "ZR"
in the size description depending on the
manufacturer (e.g. 245/40 ZR 18).
The service specifications consist of load
bearing index A and speed index B.
R If the size description of your tire includes
"ZR" and there are no service
specifications, ask the tire manufacturer in
order to find out the maximum speed.
If a service specification is available, the
maximum speed is limited according to the
speed index in the service specification.
Example: 245/40 ZR 18 97 Y. In this
example, "97 Y" is the service specification.
The letter "Y" represents the speed index
and the maximum speed of the tire is
limited to 186 mph (300 km/h).
R Every tire that has a maximum speed above
186 mph (300 km/h) must have "ZR" in the
size description and the service
specification must be given in brackets.
Example: 275/40 ZR 18 (99 Y). The speed
index "(Y)" shows that the maximum speed
of the tire is above 186 mph (300 km/h).
Ask the tire manufacturer to find out the
maximum speed.All-weather tires and winter tiresIndexSpeed ratingQ M+S 40Up to 100 mph (160 km/h)T M+S40Up to 118 mph (190 km/h)H M+S 40Up to 130 mph (210 km/h)V M+S40Up to 149 mph (240 km/h)
i
Not all tires that have the M+S
identification offer the driving
characteristics of winter tires. Winter tires
have, in addition to the M+S identification,
the i snow flake symbol on the tire
sidewall. Tires with this identification fulfill
the requirements of the Rubber
Manufacturers Association (RMA) and the
Rubber Association of Canada (RAC)
regarding the tire traction on snow and
40 Or M+S i for winter tires.Tire labeling357Wheels and tiresZ

Maximum load on one tire
Maximum load on one tire. This is calculated
by dividing the maximum axle load of one axle
by two.
PSI (pounds per square inch)
A standard unit of measure for tire pressure.
Aspect ratio
Relationship between tire height and tire
width in percent.
Tire pressure
This is pressure inside the tire applying an
outward force to each square inch of the tire's
surface. The tire pressure is specified in
pounds per square inch (psi), in kilopascal
(kPa) or in bar. The tire pressure should only
be corrected when the tires are cold. For this,
the vehicle must have been stationary for at
least three hours or not have traveled more
than 1.6 km (1 mile) in this time.
Tire pressure of cold tires
Tire pressure when the vehicle has been
stationary for at least three hours or not have
traveled more than 1.6 km (1 mile) in this
time.
Tread
The part of the tire that comes into contact
with the road.
Bead
The tire bead ensures that the tire sits
securely on the wheel. There are several steel
wires in the bead to prevent the tire from
coming loose from the wheel rim.
Sidewall
The part of the tire between the tread and the
bead.
Weight of optional extras
The combined weight of those optional extras
that weigh more than the replaced standard
part and more than 2.3 kilograms (5 lbs).
These optional extras, such as high-
performance brakes, level control, a roof rack
or a high-performance battery, are not
included in the curb weight and accessory
weight.
TIN (Tire Identification Number)
This is a unique identifier which can be used
by a tire manufacturer to identify tires, for
example for a product recall, and thus identify
the purchasers. The TIN is made up of the
manufacturer's identity code, tire size, tire
type code and the manufacturing date.
Load bearing index
The load bearing index (also load index) is a
code that contains the maximum load bearing
capacity of a tire.
Traction
Traction is the result of friction between the
tires and the road surface.
TWR (Tongue Weight Rating)
The TWR specifies the maximum permissible
weight that the ball coupling of the trailer tow
hitch can support.
Definition of terms for tires and loading361Wheels and tiresZ