2008 MERCEDES-BENZ GL450 air condition

356 Operation
Driving instructions
Read this chapter carefully before you be-
gin off-road travel.
Familiarize yourself with the vehicle char-
acteristics and gear changing before you
attempt any difficult terrain off-road driv-
ing. We recommend that you start out with
easy off-road travel.Special driving features for off-road
driving
The following driving features are available
for specific kind of operation:

Off-road – ABS (page 102)

Off-road – ESP® (page 106)

Off-road – 4-ETS (page 108)

Hill start assist system (page 196)

LOW RANGE mode* (page 201)

Differential locks* (page 204)

Downhill Speed Regulation (DSR)
(
page 273)

Off-road driving program (Vehicles
without enhanced off-road package*)
(
page 277)

Air suspension (page 278)Off-road driving rules

Engage the off-road driving program
(
page 277) or LOW RANGE mode*
(
page 201) before driving under
off-road conditions.

If necessary, activate differential
locks* (
page 204).

Make sure you select a vehicle level
(
page 279) appropriate to the topo-
graphical conditions. Always make
sure the vehicle has enough ground
clearance.

Fasten items being carried as securely
as possible (
page 295).

Always navigate gradients with the en-
gine on and with the transmission en-
gaged in a gear. Switch on the DSR
(
page 274) to help maintain a preset
speed.
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358 Operation
Driving instructions
Tires

Check the tread depth and maintain
specified tire inflation pressure
(a placard with the recommended tire
inflation pressures is located on the
driver’s door B-pillar (
page 388)).

Check tires for possible damage and
remove foreign objects.

Replace missing valve caps.
Rims

Dented or bent rims can cause tire in-
flation pressure loss and damage the
tire beads. For this reason, check and,
if necessary, change rims before driv-
ing off-road.
Vehicle tool kit

Check if the vehicle jack (page 492)
is functional.

In all cases take the vehicle tool kit, a
strong tow rope, a shovel and a small
plank (to put under the vehicle jack on
sandy soil) with you.Driving in steep terrain
Slope angle
1 Overhang angle, front
2Overhang angle, rear

Comply with the warnings
(
page 355) and rules for off-road
driving (
page 356).

Driving on embankments, slopes and
other steep inclines should only be
done straight up or downhill, i.e. in the
line of gravity. Maximum vehicle climb-
ing ability is a 100% grade which is
equivalent to a slope angle of
45 degrees. Keep in mind that the
climbing ability of the vehicle depends
on terrain conditions.
Vehicles with air sus-
pension program12
Raised level34°28°
Highway29°23°
Vehicles with
enhanced off-road
package*12
Off-road-level 336°30°
Off-road-level 234°28°
Off-road-level 131°25°
Highway29°23°
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363 Operation
Driving instructions

Avoid high engine speeds.

Shift automatic transmission to
position1 (
page 197).

Drive next to the ruts rather than
through them if at all possible.

If the ruts are too deep to drive in, drive
with one side of the vehicle on the
grassy center strip if the route permits.Returning from off-road drivingOff-road driving increases strain on the
vehicle.
We recommend that you inspect the vehi-
cle for possible damage after each off-road
trip. Recognizing any damage and a subse-
quent timely repair reduces the chance of
a possible breakdown or accident later on.
Proceed as follows:

Switch off the off-road driving program
(
page 278) or the LOW RANGE
mode* (
page 201).

Switch off the DSR (page 274).

Set the differential locks* to AUTO
(
page 205).

Lower the vehicle back to a level
suitable for road conditions, e.g. High-
way/High-speed level (
page 279).

Clean all exterior lamps and check for
possible damage.
!Check that the ruts are not too deep and
your vehicle’s clearance is sufficient. Otherwise:

your vehicle may be damaged

the underbody of the vehicle may come in
contact with the ground and you may get
stuck
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 roadway.
Inspect the tires and under the vehicle for
possible damage. If the vehicle or tires ap-
pear unsafe, have it towed to the nearest
Mercedes-Benz Light Truck Center or tire
dealer for repairs.
Damage to the vehicle may influence driving
comfort and pose the risk of accident to you
and other drivers.
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368 Operation
Driving instructions

Always secure items in the trailer to
prevent load shifts while driving.

When towing a trailer, check occasion-
ally to make sure the load is secure,
and that lighting and trailer brakes (if
so equipped) are functioning properly.

Take into consideration that when tow-
ing a trailer, the handling characteris-
tics are different and less stable from
those when operating the vehicle with-
out a trailer.
It is important to avoid sudden maneu-
vers.

The vehicle and trailer combination is
heavier, and therefore is limited in ac-
celeration and climbing ability, and re-
quires longer stopping distances.
It is more prone to reacting to cross
wind gusts, and requires more sensi-
tive steering input.

If possible, do not brake abruptly, but
rather engage the brake slightly at first
to permit the trailer to activate its
brake. Then increase the braking force.

If the transmission repeatedly shifts
between gears on inclines, manually
shift to a lower gear (select 4, 3, 2 or 1)
(
page 197).
A lower gear and reduction of speed re-
duces the chance of engine overload-
ing and/or overheating.

On very steep inclines, not manageable
with automatic transmission in1,
switch on off-road driving program
(
page 278) or LOW RANGE mode*
(
page 201).

When going down a long hill, shift into
a lower gear and use the engine’s brak-
ing effect.
Avoid riding the brakes, thus overheat-
ing the vehicle and trailer brakes.

If the engine coolant rises to an ex-
tremely high temperature (coolant tem-
perature needle approaching the red
zone) when the air conditioning is on,
turn off the air conditioning system.
Engine coolant heat can be additionally
vented by opening the windows,
switching the climate control fan speed
to high and setting the temperature
control to the maximum hot position.

Extreme care must be exercised since
your vehicle with a trailer will require
additional passing distance ahead than
when driving without a trailer.
Because your vehicle and trailer is
longer than your vehicle alone, you will
also need to go much farther ahead of
the passed vehicle before you can re-
turn to your lane.
!If the trailer should begin to sway, reduce
the vehicle’s speed immediately.
In no case attempt to straighten out the tow
vehicle and trailer by increasing the speed.
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371 Operation
Driving instructions
Telephones and two-way radios
Radio transmitters, such as a portable
telephone or a citizens band unit should
only be used inside the vehicle if they are
connected to an antenna that is installed
on the outside of the vehicle.
Refer to the radio transmitter operation
instructions regarding use of an external
antenna.Catalytic converter (gasoline engine)
Your Mercedes-Benz is equipped with
monolithic-type catalytic converters, an
important element in conjunction with the
oxygen sensors to achieve substantial con-
trol of the pollutants in the exhaust emis-
sions. Keep your vehicle in proper
operating condition by following our rec-
ommended maintenance instructions as
outlined in your Maintenance Booklet.
Oxidation catalyst (diesel engine)
Your vehicle is equipped with an oxidation
catalyst, an important element in conjunc-
tion with the oxygen sensors to achieve
substantial control of the pollutants in the
exhaust emissions. Keep your vehicle in
proper operating condition by following
our recommended maintenance instruc-
tions as outlined in your Maintenance
Booklet.
Warning!G
Never operate radio transmitters equipped
with a built-in or attached antenna (i.e. with-
out being connected to an external antenna)
from inside the vehicle while the engine is
running. Doing so could lead to a malfunc-
tion of the vehicle’s electronic system,
possibly resulting in an accident and/or
personal injury.
!To prevent damage to the catalytic convert-
ers, use only premium unleaded gasoline in this
vehicle.
Any noticeable irregularities in engine operation
should be repaired promptly. Otherwise, exces-
sive unburned fuel may reach the catalytic con-
verter, causing it to overheat and potentially
start a fire.
Warning!G
As with any vehicle, do not idle, park or op-
erate this vehicle in areas where combusti-
ble 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.
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394 Operation
Tires and wheels
1Tire and Loading Information placard
with recommended cold tire inflation
pressures
The Tire and Loading Information placard
lists the recommended cold tire inflation
pressures for maximum loaded vehicle
weight. The tire inflation pressures listed
apply to the tires installed as original
equipment.Important notes on tire inflation
pressure
Tire temperature and tire inflation pressure
are also increased while driving, depending
on the driving speed and the tire load.
If you will be driving your vehicle at high
speeds of 100 mph (160 km/h) or higher,
where it is legal and conditions allow,
consult the tire inflation pressure label on
the inside of the fuel filler flap (if available)
on how to adjust the cold tire inflation
pressure. If you do not adjust the tire infla-
tion pressure, excessive heat can build up
and result in sudden tire failure.If your vehicle is not equipped with the tire
inflation pressure label on the inside of the
fuel filler flap, contact an authorized
Mercedes-Benz Light Truck Center for
proper tire inflation pressure.
Be sure to readjust the tire inflation
pressure for normal driving speeds. You
should wait until the tires are cold before
adjusting the tire inflation pressure.
Some vehicles may have supplemental tire
inflation pressure information for vehicle
loads less than the maximum loaded vehi-
cle condition. If such information is provid-
ed, it can be found on the tire inflation
pressure label located on the inside of the
fuel filler flap (
page 374).
iData shown on Tire and Loading Information
placard example are for illustration purposes
only. Tire data are specific to each vehicle and
may vary from data shown in the illustration
below. Refer to Tire and Loading Information
placard on vehicle for actual data specific to your
vehicle.
Warning!G
If the tire inflation pressure drops
repeatedly:

Check the tires for punctures from
foreign objects.

Check to see whether air is leaking from
the valves or from around the rim.
iDriving comfort may be reduced when the
tire inflation pressure is adjusted to the value for
speeds above 100 mph (160 km/h) as specified
on the tire inflation pressure label located on the
inside of the fuel filler flap.
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416 Operation
Tires and wheels
Bar
Another metric unit for air pressure. There
are 14.5038 pounds per square inch (psi)
to 1 bar; there are 100 kilopascals (kPa)
to 1 bar.
Bead
The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the
rim.
Cold tire inflation pressure
Tire inflation pressure when your vehicle
has been sitting for at least 3 hours or
driven no more than 1 mile (1.6 km).
Curb weight
The weight of a motor vehicle with stan-
dard equipment including the maximum
capacity of fuel, oil, and coolant, and, if so
equipped, air conditioning and additional
optional equipment, but without passen-
gers and cargo.DOT (Department of Transportation)
A tire branding symbol which denotes the
tire meets requirements of the
U.S. Department of Transportation.
GAWR (G
ross Axle Weight Rating)
The GAWR is the maximum permissible
axle weight. The gross vehicle weight on
each axle must never exceed the GAWR for
the front and rear axle indicated on the
certification label located on the driver’s
door B-pillar.
GTW (G
ross Trailer Weight)
The GTW is the weight of the trailer plus
the weight of all cargo, equipment, luggage
etc. loaded on the trailer.GVW (G
ross Vehicle Weight)
The GVW comprises the weight of the
vehicle including fuel, tools, spare wheel,
installed accessories, passengers and
cargo and, if applicable, trailer tongue
load. The GVW must never exceed the
GVWR indicated on the certification label
located on the driver’s door B-pillar.
GVWR (G
ross Vehicle Weight Rating)
This is the maximum permissible vehicle
weight of the fully loaded vehicle (weight of
the vehicle including all options, passen-
gers, fuel, and cargo and, if applicable,
trailer tongue load). It is indicated on
certification label located on the driver’s
door B-pillar.
Kilopascal (kPa)
The metric unit for air pressure. There are
6.9 kPa to 1 psi; another metric unit for air
pressure is bars. There are 100 kilopascals
(kPa) to 1 bar.
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417 Operation
Tires and wheels
Maximum load rating
The maximum load in kilograms and
pounds that can be carried by the tire.
Maximum loaded vehicle weight
The sum of curb weight, accessory weight,
total load limit and production options
weight.
Maximum tire inflation pressure
This number is the greatest amount of air
pressure that should ever be put in the tire
under normal driving conditions.
Normal occupant weight
The number of occupants the vehicle is
designed to seat, multiplied by
68 kilograms (150 lbs).
Occupant distribution
The distribution of occupants in a vehicle
at their designated seating positions.Production options weight
The combined weight of those installed
regular production options weighing over
5 lbs (2.3 kilograms) in excess of those
standard items which they replace, not
previously considered in curb weight or
accessory weight, including heavy duty
brakes, ride levelers, roof rack, heavy duty
battery, and special trim.
PSI (P
ounds per square inch)
A standard unit of measure for air pressure
-> bar, kilopascal (kPa).
Recommended tire inflation pressure
Recommended tire inflation pressure for
normal driving conditions is listed on the
Tire and Loading Information placard locat-
ed on driver’s door B-pillar. Provides best
handling, tread life and riding comfort. If so
equipped, supplemental information per-
taining to special driving situations can be
found on the tire inflation pressure label on
the inside of the fuel filler flap.Rim
A metal support for a tire or a tire and tube
assembly upon which the tire beads are
seated.
Sidewall
The portion of a tire between the tread and
the bead.
TIN (Tire Identification Number)
Unique identifier which facilitates efforts
by tire manufacturers to notify purchasers
in recall situations or other safety matters
concerning tires and gives purchases the
means to easily identify such tires. The TIN
is comprised of “Manufacturer’s identifica-
tion mark”, “Tire size”, “Tire type code”
and “Date of manufacture”.
Tire load rating
Numerical code associated with the
maximum load a tire can support.
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