2008 MERCEDES-BENZ GL550 power steering

142 Controls in detail
Memory function*
Storing positions into memory
Adjust the seats (page 45).
On the driver’s side, additionally adjust
the steering wheel (
page 50) and ex-
terior rear view mirrors (
page 51) to
the desired positions.
Press memory buttonM.
Release memory buttonM and press
stored position button1,2 or3 within
3 seconds.
All settings are stored to the selected
position.
Recalling positions from memory
Press and hold stored position
button1,2 or3 until the seat, steering
wheel and exterior rear view mirrors
have fully moved to the stored posi-
tions.
!Do not operate the power seats using
memory buttonM if the seat backrest is in an
excessively reclined position. Doing so could
cause damage to front or rear seats.
Move seat backrest to an upright position first.
iReleasing the stored position button stops
movement to the stored positions immediately.
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198 Controls in detail
Automatic transmission
Steering wheel gearshift control
With drive positionD selected, you can
limit or extend the gear range.
1Left button: limiting gear range or
downshift
2Right button: extending gear range or
upshiftEffect
çThe transmission shifts through
second gear only.
Allows the use of engine’s
braking power when driving:

on steep downgrades

in mountainous regions

under extreme operating
conditions
æThe transmission operates in
first gear only.
For maximum use of engine’s
braking effect on very steep or
lengthy downgrades.
!Allow engine to warm up under low load use.
Do not place full load on the engine until the
operating temperature has been reached.
Shift into reverse gearR or park positionP only
when the vehicle is stopped.
Avoid spinning of a drive wheel for an extended
period when driving off on slippery road
surfaces. This may cause serious damage to the
drivetrain which is not covered by the
Mercedes-Benz Limited Warranty.
iYou cannot shift with the steering wheel
gearshift buttons when the transmission is in
positionP,N orR.
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204 Controls in detail
Differential locks*
For more information on Off-road driving,
see “Off-road driving” (
page 355).
Vehicles with enhanced off-road package*
are equipped with automatic locks for the
center and rear axle differential to improve
vehicle traction.

The center differential compensates
for differences in wheel rotation be-
tween the front and rear axle.

The rear axle differential compensates
differences between the rear wheels.A few words about differentials and
differential 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, makes this essential function pos-
sible.
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 201) also en-
hances off-road driving capabilities
(
page 355).
More extreme off-road conditions may call
for another solution, engaging a differen-
tial lock or preventing the differential from
operating altogether. This vehicle comes
with two differential locks: transfer case
(center) and rear. Each can be engaged
simply by operating a rotary switch located
on the center console (
page 205). When
the transfer case (center) differential is
locked, the combined (or average) speed
of the front wheels is identical to the com-
bined rear wheel speed. When the rear
differential is locked, both rear wheels turn
iAt the front axles, the 4-ETS system
(
page 107) compensates for any traction
problems.
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261 Controls in detail
Driving systems
Warning!G
Distronic adaptive cruise control is no
substitute for active driving involvement. It
does not react to pedestrians or on station-
ary objects, nor does it recognize or predict
the lane curvature or the movement of
preceding vehicles.
Distronic can only apply a maximum of 20%
of the vehicle’s braking power.
It is the driver’s responsibility at all times to
be attentive to the road, weather and traffic
conditions. Additionally, the driver must
provide the steering, braking and other
driving inputs necessary to remain in control
of the vehicle.
High-frequency sources such as toll
stations, speed measuring systems etc. can
cause the Distronic system to malfunction.
Warning!G
Distronic requires familiarity with its opera-
tional characteristics. We strongly recom-
mend that you review the following
information carefully before operating the
system.
Warning!G
Distronic cannot take road and traffic condi-
tions into account. Only use Distronic if the
road, weather and traffic conditions make it
advisable to travel at a constant speed.
Warning!G
Use of Distronic can be dangerous on slip-
pery roads. Rapid changes in tire traction
can result in wheel spin and loss of control.
Distronic does not act upon adverse sight
and distance conditions. Do not use
Distronic during conditions of fog, heavy
rain, snow or sleet.
Warning!G
Distronic cannot take weather conditions
into account. Switch off Distronic or do not
switch it on if:

roads are slippery or covered with snow
or ice. The wheels could lose traction
while braking or accelerating, and the
vehicle could skid.

the sensor is dirty or visibility is
diminished due to snow, rain or fog, for
example. The distance control system
functionality could be impaired.
Always pay attention to surrounding traffic
conditions even while Distronic is switched
on. Otherwise, you may not be able to recog-
nize dangerous situations until it is too late.
This could cause an accident in which you
and others could be injured.
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327 Controls in detail
Useful features
Heated steering wheel*
The steering wheel heating warms up the
leather area of the steering wheel.
The stalk is on the lower left-hand side of
the steering wheel.
1Switching on
2Indicator lamp
3Switching offSwitching on
Switch on the ignition (page 42).
Turn switch at the tip of stalk in the
direction of arrow1.
The steering wheel is heated. Indicator
lamp2 comes on.Switching off
Turn switch at the tip of stalk in the
direction of arrow3.
The heated steering wheel is switched
off. Indicator lamp2 goes out.
For information on the steering wheel, see
“Multifunction steering wheel”
(
page 30).
iThe steering wheel heating is turned off tem-
porarily and the indicator lamp2 remains on
when

the temperature of the vehicle interior is
above 86°F (30°C)

the temperature of the steering wheel is
above 95°F (35°C)
When these conditions do not apply anymore,
steering wheel heating continues.
iIndicator lamp2 flashes or goes out

in case of power surge or undervoltage

in case of a steering wheel heating malfunc-
tion
iThe steering wheel heating switches off
automatically when you remove the SmartKey
from the starter switch or, on vehicles with
KEYLESS-GO*, when you switch off the ignition
(
page 41) and open the driver’s door.
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348 Operation
Driving instructions
Power assistanceBrakes
Warning!G
With the engine not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to brake and steer the ve-
hicle.
Warning!G
After driving in heavy rain for some time
without applying the brakes or through wa-
ter deep enough to wet brake components,
the first braking action may be somewhat re-
duced and increased pedal pressure may be
necessary to obtain expected braking ef-
fect. Maintain a safe distance from vehicles
in front.
Resting your foot on the brake pedal will
cause excessive and premature wear of the
brake pads.
It can also result in the brakes overheating,
thereby significantly reducing their effec-
tiveness. It may not be possible to stop the
vehicle in sufficient time to avoid an acci-
dent.
!Operational or performance test must only
be conducted on a two-axle dynamometer. If
such tests are necessary, contact an authorized
Mercedes-Benz Light Truck Center. You could
otherwise seriously damage the brake system or
the transfer case which is not covered by the
Mercedes-Benz Limited Warranty.
!Because the ESP® operates automatically,
the engine and ignition must be shut off
(SmartKey in starter switch position0 or1 or
KEYLESS-GO* start/stop button in
position0or1) when testing the parking brake
on a brake test dynamometer and such testing
should be no longer than 10 seconds.
Active braking action through the ESP
® may
otherwise seriously damage the brake system
which is not covered by the Mercedes-Benz
Limited Warranty.
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415 Operation
Tires and wheels
Tire ply material
1Plies in sidewall
2Plies under tread
This marking tells you about the type of
cord and number of plies in the sidewall
and under the tread.Tire and loading terminology
Accessory weight
The combined weight (in excess of those
standard items which may be replaced) of
automatic transmission, power steering,
power brakes, power windows, power
seats, radio, and heater, to the extent that
these items are available as
factory-installed equipment (whether
installed or not).
Air pressure
The amount of air inside the tire pressing
outward on each square inch of the tire.
Air pressure is expressed in pounds per
square inch (psi), or kilopascal (kPa) or
bars.
Aspect ratio
Dimensional relationship between tire
section height and section width
expressed in percentage.
Warning!G
The temperature grade for this tire is estab-
lished for a tire that is properly inflated and
not overloaded. Excessive speed, underin-
flation, or excessive loading, either sepa-
rately or in combination, can cause
excessive heat build-up and possible tire
failure.
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
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432 Operation
Vehicle care
Use a soft, clean cloth and a mild win-
dow cleaning solution on all outside
and inside glass surfaces.
An automotive glass cleaner is recom-
mended.Light alloy wheels
If possible, clean wheels once a week.
Use Mercedes-Benz approved Wheel
Care, a soft bristle brush and a strong
spray of water for cleaning the light al-
loy wheels.Plastic and rubber parts
Use a gentle dishwashing detergent or
mild detergent for delicate fabrics as a
washing solution.
Wipe with a cloth moistened in a
lukewarm solution.
The surface may temporarily change
color. If this is the case, wait for it to
dry.
!Fold the windshield wiper arms back onto
the windshield before turning the SmartKey in
the starter switch or pressing the KEYLESS-GO
start/stop button (vehicles with KEYLESS-GO*).
Hold on to the wiper when folding the wiper arm
back. If released, the force of the impact from
the tensioning spring could crack the windshield.
!To clean the window interior, do not use a
dry cloth, abrasives, solvents or cleaners con-
taining solvents. Do not touch the inside of the
front, rear or side windows and the power
tilt/sliding sunroof* or rear panorama roof with
hard objects such as an ice scraper or ring.
Doing so may damage the windows.
!Only use acid-free cleaning materials. Acid
may cause corrosion or damage the clear coat.
!The vehicle should not be parked for an ex-
tended period of time immediately after it has
been cleaned, especially not after the wheel rims
have been cleaned with wheel rim cleaner.
Wheel rim cleaners can lead to increased
corrosion of the brake disks and brake pads.
Non-approved wheel cleaners may also damage
the wheel paint if the car is not driven after
cleaning. Therefore, the vehicle’s brake system
should always be warmed-up before it is parked
after cleaning. To do so, please drive your vehicle
for several minutes to allow the brakes to dry.
When applying Mercedes-Benz approved Tire
Care and Mercedes-Benz approved Wheel Care
products, take care not to spray them on the
brake disks.
Warning!G
Do not use cleaners or cockpit care sprays
containing solvents to clean the cockpit or
the steering wheel. Cleaners containing sol-
vents will make the surface porous and vehi-
cle occupants could suffer serious injuries
from plastic parts coming loose in the event
of air bag deployment.

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