2003 MERCEDES-BENZ G55AMG four wheel drive

144 Controls in detailDifferential locksA few words about differentials and dif-ferential locks
When a vehicle negotiates a turn, wheels
on the outside of the curve must travel far-
ther and rotate faster than the inside
wheels. The differential, the operation of a
set of gears that allows the powered
wheels in a vehicle to turn at different
speeds, make this essential function possi-
ble.
The drawback is that the differential also
sends most of the engine's power to the
wheel with the least load or strain on it. For
example, if one of a vehicle's powered
wheels sits on a patch of snow and spins
because there is no traction, all of the en-
gine's power will go to that wheel because
the power will take the path of least resis-
tance. Meanwhile, the opposite wheel, sit-
ting on dry pavement where it could get
enough grip to start the vehicle moving,
sits idle because it receives no power.The Electronic Traction System (ETS) ad-
dresses this problem and provides for
good control and steering ability by auto-
matically slowing the slipping wheel and
thus increasing the power to the other
non-slipping drive wheels to get the vehicle
moving. The ESP and ETS in this vehicle
feature such intelligent limited-slip differ-
ential technology, ideally suited for
on-road and light off-road driving. Transfer
case position LOW (
page 141) also en-
hances off-road driving capabilities
(
page 203).
More extreme off-road conditions may call
for another solution, engaging a differen-
tial lock or preventing the differential from
operating altogether. As part of its stan-
dard equipment, this vehicle comes with
three differential locks: front, transfer case
(center) and rear. Each can be engaged
simply by pushing dashboard-mounted
buttons in sequential order (center, rear,
front) (
page 145). When the transfer
case (center) differential is locked, half of
the engine's power is automatically distrib-
uted to the front wheels and half to the rear wheels. When the rear differential is
locked, power going to the rear wheels is
equally distributed, so that both rear
wheels turn at the same speed and torque.
When the front differential is locked, all
four wheels now turn with equal power and
torque. Please be aware that engaging the
differential locks will significantly reduce
the steering ability of the vehicle.
For your safety and the safety of others
and to prevent damage to the vehicle, the
differential locks must not be engaged
when driving on paved roads. It is impor-
tant to understand that during
on-road/paved driving, differentials are
absolutely necessary for providing the es-
sential control and steering ability of the
vehicle. The differential locks, therefore,
must not be engaged when driving on
paved roads and should only be used to
the extent necessary to negotiate off-road
conditions which can not be handled by
the systems (automatic 4-ETS, the ESP,
manual switch position “LOW” of transfer
case) this vehicle comes equipped with.

201 Operation
Driving instructions
Tire traction
The safe speed on a wet, snow covered or
icy road is always lower than on a dry road.
You should pay particular attention to the
condition of the road whenever the outside
temperatures are close to the freezing
point.
Mercedes-Benz recommends M+S rated
radial-ply tires with a minimum tread depth
of approximately
1⁄8in (4 mm) for the win-
ter season for all four wheels to insure nor-
mal balanced handling characteristics. On
packed snow, they can reduce your stop-
ping distance as compared with summer
tires.Stopping distance, however, is still consid-
erably greater than when the road is not
covered with snow or ice. Exercise appro-
priate caution.
Tire speed rating
G500, G55AMG
Your vehicle is factory equipped with
“V”-rated tires, which have a speed rating
of 150 mph (240 km/h).An electronic speed limiter prevents your
vehicle from exceeding the speed rating.
Despite of the tire speed rating, local
speed limits should be obeyed. Use pru-
dent driving speeds appropriate to prevail-
ing conditions.
Warning!
G
If ice has formed on the road, tire traction
will be substantially reduced. Under such
weather conditions, drive, steer and brake
with extreme caution.
!Avoid spinning of one drive wheel. This
may cause serious damage to the drive
train which is not covered by the
Mercedes-Benz Limited Warranty.iAdditional information on winter tires
can be found under “Winter tires”
(page 228).
Warning!
G
Even when permitted by law, never operate
a vehicle at speeds greater than the maxi-
mum speed rating of the tires.
Exceeding the maximum speed for which
tires are rated can lead to sudden tire fail-
ure, causing loss of vehicle control and pos-
sibly resulting in an accident and/or serious
injury and possible death, for you and for
others.

228 OperationWinter driving
Winter drivingBefore the onset of winter, have your vehi-
cle winterized at an authorized
Mercedes-Benz Light Truck Center. This
service includes:

Check of anticorrosion and antifreeze
concentration.


Addition of cleaning concentrate to the
water of the windshield and headlamp
cleaning system. Add MB Concentrate
“S” to a premixed windshield washer
solvent/antifreeze which is formulated
for below freezing temperatures
(page 321).


Battery test. Battery capacity drops
with decreasing ambient temperature.
A well charged battery helps to ensure
that the engine can be started even at
low ambient temperatures.


Tire change. We recommend M+S rat-
ed radial-ply tires on all four wheels for
the winter season.
Winter tires
Always use winter tires at temperatures
below 39°F (4°C) and whenever wintry
road conditions prevail. Use of winter tires
is the only way to achieve the maximum ef-
fectiveness of the ABS, ESP, EBB and
4-ETS in winter operation.
For safe handling, ensure that all winter
tires mounted are of the same make and
have the same tread design.
Always observe the speed rating of the
winter tires installed on your vehicle. If the
maximum speed for which your tires are
rated is below the speed rating of your ve-
hicle, you must place a notice to this effect
where it will be seen by the driver. Such no-tices are available from your tire dealer or
from any authorized Mercedes-Benz Light
Truck Center.
Block heater (Canada only)
The engine is equipped with a block heat-
er.
The electrical cable may be installed at
your authorized Mercedes-Benz Center.
Warning!
G
Winter tires with a tread depth under 0.16 in
(4 mm) must be replaced. They are no long-
er suitable for winter operation.
Warning!
G
If you use your spare tire when winter tires
are fitted on the other wheels, be aware that
the difference in tire characteristics may
very well impair turning stability and that
overall driving stability may be reduced.
Adapt your driving style accordingly.
Have the spare tire replaced with a winter
tire at the nearest authorized
Mercedes-Benz Light Truck Center.

229 Operation
Winter driving
Snow chains
Snow chains should only be driven on
snow-covered roads at speeds not to ex-
ceed 30 mph (50 km/h). Remove chains
as soon as possible when driving on roads
without snow. Observe the following guidelines when us-
ing snow chains:


Chains cannot be mounted on all
wheel/tire combinations.


Chains should only be used on all four
wheels. With only two chains available,
they should be mounted on the rear
wheels. Follow the manufacturer’s
mounting instructions.


Use only snow chains that are ap-
proved by Mercedes-Benz. Your autho-
rized Mercedes-Benz Light Truck
Center will be glad to advise you on this
subject.
iWhen driving with snow chains, you
may wish to deactivate the ESP
(page 76) before setting the vehicle
in motion. This will improve the
vehicle’s traction.