2008 MERCEDES-BENZ GL450 Break light

12 Introduction
Operator’s Manual
Maintenance
The Maintenance Booklet describes all the
necessary maintenance work which should
be performed at regular intervals.
Always have the Maintenance Booklet with
you when you take the vehicle to an
authorized Mercedes-Benz Light Truck
Center for service. The service advisor will
record each service in the booklet for you.Roadside Assistance
The Mercedes-Benz Roadside Assistance
Program provides factory-trained technical
help in the event of a breakdown. Calls to
the toll-free Roadside Assistance number
1-800-FOR-MERCedes (in the USA)
1-800-387-0100 (in Canada)
will be answered by Mercedes-Benz
Customer Assistance Representatives
24 hours a day, 365 days a year.
Roadside Assistance will be provided in
accordance with standard program guide-
lines which include providing service to the
vehicle up to a reasonable distance from a
paved roadway. We will make every effort
to assist in a breakdown situation, howev-
er, the accessibility of your vehicle will be
determined by our authorized
Mercedes-Benz Light Truck Center techni-
cian or the tow service provider on a
case-by-case basis and may be a factor in
our ability to respond.Additional charges may be applicable for a
breakdown location determined not to be a
reasonably accessible roadside location as
determined by our authorized technician
and tow service provider.
For additional information refer to the
Mercedes-Benz Roadside Assistance
Program brochure in your vehicle literature
portfolio.
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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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367 Operation
Driving instructions
Make sure the automatic transmission
is set toP (
page 191).
Set the parking brake for the vehicle
(
page 67).
Start the engine (page 56).
Set the vehicle level to Highway
(
page 279).
Vehicle with ADS*: Set the ADS* to
AUTO or COMFORT (
page 278).
Turn off the engine (page 68).
Close all doors and the tailgate.
Attach the trailer.
Plug in all electrical connectors.
Towing a trailer
There are many different laws, including
speed limit restrictions, having to do with
trailer towing. Make sure your rig will be le-
gal, not only for where you reside, but also
for where you will be driving. A good
source for this information can be the po-
lice or local authorities.Note the following points, when driving
with the trailer:
In order to gain skill and an understand-
ing of the vehicle’s behavior, you
should practice turning, stopping and
backing up in an area which is free from
traffic.

Before you start driving check the

trailer hitch

break-away switch

safety chains

electrical connections

lighting and tires

Adjust the mirrors (page 51) to
permit unobstructed view beyond rear
of trailer.

If the trailer has electric brakes, start
your vehicle and trailer moving slowly,
and then apply only the trailer brake
controller by hand to make sure the
brakes are working properly.
!Do not connect a trailer brake system (if
trailer is so equipped) directly to the vehicle’s
hydraulic brake system, as your vehicle is
equipped with antilock brakes. If you do, neither
the vehicle’s brakes nor the trailer’s brakes will
function properly.
iThe provided vehicle electrical connector for
trailer towing has a brake signal wire for hook-up
to a brake controller.
You should consider using a trailer sway control
system. For further information, contact an
authorized Mercedes-Benz Light Truck Center.
iWhen you are towing a trailer, the vehicle
level always remains in the Highway setting.
The following applies additionally when towing a
trailer:

The vehicle is lowered to the highway level
when it reaches a speed of 5 mph (8 km/h)
if not set to highway level.

The high-speed level is not available.
The restrictions that apply to towing also apply
when using accessories that are connected to
the trailer power socket, such as a bicycle rack.
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380 Operation
Engine compartment
Engine oil
The amount of oil your engine needs will
depend on a number of factors, including
driving style. Increased oil consumption
can occur when

the vehicle is new

the vehicle is driven frequently at
higher engine speeds
Engine oil consumption checks should only
be made after the vehicle break-in period.Checking engine oil level
When checking the oil level

the vehicle must be parked on level
ground

the vehicle must have been stationary
for at least 5 minutes with the engine
turned off
Example illustration GL 450 (GL 320 CDI,
GL 550 similar)
1Oil dipstick
2Upper mark
3Lower mark
Open the hood (page 378).
Pull out oil dipstick1.
Wipe oil dipstick1 clean.
Fully insert oil dipstick1 into the
dipstick guide tube.
Pull out oil dipstick1 again after
approximately 3 seconds to obtain
accurate reading.
The oil level is correct when it is be-
tween lower mark3 (min.) and upper
mark2 (max.) of the oil dipstick.
If necessary, add engine oil
(
page 381).
For more information on engine oil, see
“Technical data” section (
page 562) and
(
page 564).
!Do not use any special lubricant additives,
as these may damage the drive assemblies.
Using special additives not approved by
Mercedes-Benz may cause damage not covered
by the Mercedes-Benz Limited Warranty.
More information on this subject is available at
any Mercedes-Benz Light Truck Center.
iThe filling quantity between the upper and
lower marks on the oil dipstick is approximately
2.1 US qt. (2.0 l).
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384 Operation
Tires and wheels
Contact an authorized Mercedes-Benz
Light Truck Center for information on test-
ed and recommended rims and tires for
summer and winter operation. They can
also offer advice concerning tire service
and purchase.Important guidelines

Only use sets of tires and rims of the
same type and make.

Tires must be of the correct size for the
rim.

Break in new tires for approximately
60 miles (100 km) at moderate
speeds.

Regularly check the tires and rims for
damage. Dented or bent rims can
cause tire inflation pressure loss or
damage to the tire beads.

If vehicle is heavily loaded, check tire
inflation pressure and correct as
required.

Do not allow your tires to wear down
too far. Adhesion properties on wet
roads are sharply reduced at tread
depths of less than
1/8in (3 mm).

When replacing individual tires, you
should mount new tires on the front
wheels first (on vehicles with
same-sized wheels all around).
Warning!G
Replace rims or tires with the same designa-
tion, manufacturer and type as shown on the
original part. Contact an authorized
Mercedes-Benz Light Truck Center for fur-
ther information. If incorrectly sized rims
and tires are mounted:

The wheel brakes or suspension
components can be damaged.

The operating clearance of the wheels
and the tires may no longer be correct.
Warning!G
Worn, old tires can cause accidents. If the
tire tread is badly worn, or if the tires have
sustained damage, replace them.
When replacing rims, only use genuine
Mercedes-Benz wheel bolts specified for the
particular rim type. Failure to do so can
result in the bolts loosening and possibly an
accident.
Retreaded tires are not tested or recom-
mended by Mercedes-Benz, since previous
damage cannot always be recognized on re-
treads. The operating safety of the vehicle
cannot be assured when such tires are used.
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593 Index
Turn signal lamps
Cleaning lenses 429
Messages in the multifunction
display 482
Replacing bulbs 505
Turn signals 62
Additional in mirrors 505
Bulbs 505, 513
Cleaning lenses 429
Indicator lamps 27
Turning off the engine 69
TWR (Tongue Weight Rating) 418
U
Uniform Tire Quality Grading
Standards 418
Units, Settings
Speedometer 173
Temperature 173
Unleaded gasoline, Premium 563
Unlocking the vehicle see Key
Uphill driving
Cruise control 257
Upholstery
Cleaning and care of 434
Useful features 315V
Vehicle
Battery 528
Break-in period 346
Care 425
Control system, Settings menu 168
Dimensions 560
Locking/unlocking 40, 67, 112
Locking/unlocking in an
emergency 496
Modifications and alterations,
Operating safety 17
Proper use of 17
Total load limit 418
Towing 538
Washing 425
Weights 561
Vehicle and trailer weights and
ratings 365
Vehicle care 425
Vehicle Identification Number see VIN
Vehicle jack 492, 493
Vehicle level control 279Vehicle level control (Vehicles with
enhanced Off-road Package*) 283
Vehicle level control*
Messages in the multifunction
display 486
Vehicle lighting 377
Vehicle loading
Cargo compartment cover blind 310
Cargo net* 312
Cargo tie-down rings 302
Carriers* 295
Crossbars* 295
Expanding cargo compartment 304
Hooks 304
Load limit 389
Loading instructions 301
Loading terminology 415
Parcel nets 319
Roof rails 295
Terminology 415
Vehicle maximum load on the tire 418
Vehicle Recovery services, Stolen
(Tele Aid) 338
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