2008 MERCEDES-BENZ GL550 tow

280 Controls in detail
Driving systems
The parked vehicle begins adjusting to the
set vehicle level as soon the doors and tail-
gate are

unlocked
or

opened or closed with the vehicle
unlocked
In order to operate the vehicle level control
switch (
page 281), however, the engine
must be running.
For information on off-road driving, see
“Off-road driving” (
page 355).
Warning!G
Make sure that no one is near the wheel
housing or under the vehicle when you lower
the vehicle while it is standing still. Limbs
could become wedged into or under the ve-
hicle.
For safety reasons, the vehicle can only be
lowered with all doors and the tailgate
closed. Lowering is interrupted if a door or
the tailgate is opened and will continue after
the door is closed again.
Warning!G
Please be aware that by raising the vehicle
level, the center of gravity also rises. There-
fore, always ensure that the vehicle level is
as low as possible. With higher ride height
the ESP
® may activate earlier in certain
situations.
Adapt your speed and driving to possible
changed driving behavior of the vehicle after
changing the vehicle level. The ESP
® cannot
prevent accidents, including those resulting
from excessive speed. The ESP
® cannot pre-
vent the natural laws of physics from acting
on the vehicle.
!Keep in mind that in rough or uneven ter-
rain, adjusting the vehicle to a lower level may
cause the vehicle underbody to come in contact
with the ground and result in damage to the vehi-
cle underbody. Always make sure the vehicle has
sufficient ground clearance before adjusting it to
a lower level.
!Before jacking up the vehicle with equip-
ment that lifts one or more of the wheels com-
pletely off of the ground, remove the SmartKey
from the starter switch.
!Please also note the information in the sec-
tion on towing (
page 538).
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281 Controls in detail
Driving systems
Vehicles without enhanced Off-road
Package*
The switch is located on the upper part of
the center console.
1Vehicle level switch
2Indicator lampBasic settings
The following vehicle chassis ride heights
can be selected using the vehicle level
switch in the center console:The following is the approximate change in
ride height for each of the level settings:
LevelDriving situation
RaisedFor off-road driving or driv-
ing in rough terrain. The in-
dicator lamp is on.
HighwayFor driving on paved roads
in fair or better condition.
The indicator lamp is off.
iThe third available level is the high-speed
level that is set automatically.
LevelRide height
Raised+ 3.1 in (80 mm)
Highway+/- 0 in (0 mm)
High-speed- 0.6 in (-15 mm)
iVehicles with ADS*:
Depending on the ADS setting (
page 278), the
vehicle will be lowered to the high-speed level
when traveling at higher speeds. At speeds
below 40 mph (64 km/h) at the latest, it will be
returned to the highway level.
iThe high-speed level is not available if tow-
ing a trailer. For more information on towing a
trailer, see “Trailer towing” (
page 364).
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284 Controls in detail
Driving systems
The following is the approximate change in
ride height for each of the level settings:You can only select the off-road levels be-
low a certain speed. At higher speeds, the
message
Level Selection Not Permitted
appears in the multifunction display.
You can select

Off-road level 1: selectable below
60 mph (96 km/h)

Off-road level 2: selectable below
40 mph (64 km/h)

Off-road level 3: selectable below
20 mph (30 km/h)Off-road levels
LevelRide height
Off-road 3+ 4.3 in (110 mm)
Off-road 2+ 3.1 in (80 mm)
Off-road 1+ 1.2 in (30 mm)
Highway+/- 0 in (0 mm)
High-speed- 0.6 in (-15 mm)
iVehicles with ADS*:
Depending on the ADS setting (
page 278), the
vehicle will be lowered to the high-speed level
when traveling at higher speeds. At speeds be-
low 40 mph (64 km/h) at the latest, it will be re-
turned to the highway level.
iThe high-speed level is not available if tow-
ing a trailer. For more information on towing a
trailer, see “Trailer towing” (
page 364).
Warning!G
Vehicle off-road level 3 is not intended for
use on paved roads. This vehicle level is only
intended for driving on rough terrain under
special requirements.

Only select off-road level 3 if you are
driving on rough terrain under especially
difficult conditions.

Adapt your driving style to the modified
conditions.

Do not exceed a speed of 20 mph
(30 km/h).

Avoid extreme, quick steering move-
ments.

Keep in mind that the vehicle’s driving
characteristics are modified.
You should therefore drive in off-road level 3
with particular caution as it could otherwise
lead to an accident and/or serious injury to
you or others.
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292 Controls in detail
Driving systems
Switching off
Press Parktronic switch1.
Indicator lamp2 comes on.
Switching on
Press Parktronic switch1 once more.
Indicator lamp2 goes out.Parktronic system* malfunction
If only the red distance segments illumi-
nate and an acoustic warning sounds,
there is a malfunction in the Parktronic
system. The Parktronic system will auto-
matically switch off after 20 seconds and
the indicator lamp in the Parktronic switch
comes on.
Have the Parktronic system checked
by an authorized Mercedes-Benz Light
Truck Center as soon as possible.
If only the red distance segments illumi-
nate and no acoustic warning sounds, the
Parktronic system sensors are dirty (e.g.
slush, snow or ice) or there is an interfer-
ence from other radio or ultrasonic signals
(e.g. working jackhammers, car wash or
the air brakes of trucks). The Parktronic
system will automatically switch off after
20 seconds and the indicator lamp in the
Parktronic switch comes on.
Switch off the ignition (page 42).
Clean the Parktronic system sensors
(
page 430).
Switch on the ignition (page 42).
or
Check the Parktronic system operation
at another location to rule out interfer-
ence from outside radio or ultrasonic
signals.
iThe Parktronic system switches on
automatically when you switch on the ignition
(
page 42).
Vehicles with original equipment Mercedes-Benz
Trailer Hitch Kit:
The rear Parktronic sensor will automatically
disengage when towing a trailer.
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302 Controls in detail
Loading
The gross vehicle weight which is the
weight of the vehicle including fuel, tools,
spare wheel, installed accessories, pas-
sengers and luggage/cargo must never
exceed the load limit and Gross Vehicle
Weight Rating (GVWR) for your vehicle as
specified on the placard located on the
driver’s door B-pillar (
page 550). In addi-
tion, the load must be distributed in such a
way so that the weight on each axle never
exceeds the Gross Axle Weight Rating
(GAWR) for the front and rear axle. The
GVWR and GAWR for your vehicle are indi-
cated on the certification label which can
be found on the driver’s door B-pillar
(
page 550).
For more information, see “Tire and Load-
ing Information” (
page 388).
The handling characteristics of a fully load-
ed vehicle depend greatly on the load dis-
tribution. It is therefore recommended to
load the vehicle according to the illustra-
tions shown, with the heaviest items being
placed towards the front of the vehicle.Please pay attention to and comply with
the following instructions when loading the
vehicle and transporting cargo:

Always place items being carried
against front or rear seat backrests,
and fasten them as securely as possi-
ble.

The heaviest portion of the cargo
should always be kept as low as possi-
ble against front or rear seat backrests.
For additional safety when transporting
cargo while the rear seats are unoccupied,
fasten the outer seat belts crosswise into
the opposite side buckles.
Cargo tie-down rings
Your vehicle is equipped with eight cargo
tie-down rings.
Carefully secure cargo by applying even
load on all rings with rope of sufficient
strength to hold down the cargo.
iThe cargo compartment is the preferred
place to carry objects. The expanded cargo com-
partment (
page 304) should only be used for
items which do not fit in the cargo compartment
alone.
iWhile the cargo net* (page 312) will help
protect you from smaller objects, it cannot pre-
vent the movement of large, heavier objects into
the passenger compartment in an accident, dur-
ing hard braking or sudden maneuvers. Such
items must be properly secured using the cargo
tie-down rings in the cargo compartment floor.
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335 Controls in detail
Useful features
Roadside Assistance button•
The Roadside Assistance button• is
located below the center armrest cover.
1Roadside Assistance button•
Open the storage compartment
(
page 318).
Press and hold button1 (for longer
than 2 seconds).
A call to a Mercedes-Benz Roadside
Assistance dispatcher will be initiated.
The button will flash while the call is in
progress. The message
Connecting Call will appear in the
multifunction display.When the connection is established, the
message
Call Connected appears in the
multifunction display. The Tele Aid system
will transmit data generating the vehicle
identification number, model, color and
location (subject to availability of cellular
and GPS signals).
A voice connection between the Roadside
Assistance dispatcher and the occupants
of the vehicle will be established.
Describe the nature of the need for as-
sistance.The Mercedes-Benz Roadside Assistance
dispatcher will either dispatch a qualified
Mercedes-Benz technician or arrange to
tow your vehicle to the nearest
Mercedes-Benz Light Truck Center. For
services such as labor and/or towing,
charges may apply. Refer to the Roadside
Assistance Manual for more information.
The following is only available in the USA:

Sign and Drive services: Services such
as jump start, a few gallons of fuel or
the replacement of a flat tire with the
vehicle spare tire are obtainable.
iWhile the call is connected you can change
to the navigation menu by pressing the NAV
button on the COMAND system unit.
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350 Operation
Driving instructions
Parking brake
When driving on wet roads or dirt covered
surfaces, road salt and/or dirt can get into
the parking brake. To prevent corrosion
and a reduction in the braking power of the
parking brake, observe the following:
From time to time, lightly engage the
parking brake before driving off.
Drive a distance of approximately
110 yds (100 m) at a maximum speed
of 12 mph (20 km/h).
Driving off
Apply the brakes to test them briefly after
driving off. Perform this procedure only
when the road is clear of other traffic.
Warm up the engine smoothly. Do not
place full load on the engine until the oper-
ating temperature has been reached.Parking
Warning!G
While performing this procedure, please
assure that the vehicle is stopped before
applying the parking brake. Otherwise the
rear wheels could lock up. You could lose
control of the vehicle and cause an accident.
In addition, the vehicle’s brake lights do not
light up when the parking brake is engaged.
Make sure not to endanger any other road
users when you engage the parking brake.
!When driving off on a slippery surface, do
not allow a drive wheel to spin for an extended
period with the ESP
® switched off. Doing so may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
!Simultaneously depressing the accelerator
pedal and applying the brake reduces engine
performance and causes premature brake and
drivetrain wear.
Warning!G
Do not park this vehicle in areas where com-
bustible materials such as grass, hay or
leaves can come into contact with the hot
exhaust system, as these materials could be
ignited and cause a vehicle fire.
To reduce the risk of personal injury or
damage to the vehicle drivetrain as a result
of vehicle movement, before turning off the
engine and leaving the vehicle always:

Keep right foot on brake pedal.

Firmly depress parking brake pedal.

Set the automatic transmission to
positionP.

Slowly release brake pedal.

When parked on an incline, turn front
wheel towards the road curb.
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351 Operation
Driving instructions
Tires
Treadwear indicators (TWI) are required by
law. These indicators are located in six
places on the tread circumference and
become visible at a tread depth of
approximately
1/16in (1.6 mm), at which
point the tire is considered worn and
should be replaced.The treadwear indicator appears as a solid
band across the tread.
Specified tire inflation pressures must be
maintained. This applies particularly if the
tires are subjected to high loads (e.g. high
speeds, heavy loads, high ambient temper-
atures).

Turn the SmartKey or the SmartKey with
KEYLESS-GO* to starter switch
position0 and remove, or press
KEYLESS-GO* start/stop button (vehi-
cles with KEYLESS-GO*).

Take the SmartKey or the SmartKey with
KEYLESS-GO* with you and lock vehicle
when leaving.
Warning!G
If you feel a sudden significant vibration or
ride disturbance, or you suspect that possi-
ble damage to your vehicle has occurred,
you should turn on the hazard warning flash-
ers, carefully slow down, and drive with cau-
tion to an area which is a safe distance from
the road.
Inspect the tires and the vehicle underbody
for possible damage. If the vehicle or tires
appear unsafe, have the vehicle towed to
the nearest Mercedes-Benz Light Truck
Center or tire dealer for repairs.
Warning!G
Although the applicable federal motor
vehicle safety laws consider a tire to be
worn when the treadwear indicators (TWI)
become visible at approximately
1/16in
(1.6 mm), we recommend that you do not
allow your tires to wear down to that level.
As tread depth approaches
1/8in (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.
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