four wheel drive MERCEDES-BENZ GL550 2008 X164 Owner's Manual

197 Controls in detail
Automatic transmission
On uphill grades with a gradient angle of
more than 5°, the hill start assist system
maintains the pressure in the brake sys-
tem for approximately 1 second after you
have released the brake pedal. Therefore,
you can start off smoothly without the
vehicle moving immediately after releasing
the brake pedal.
The hill start assist system is inactive

when starting off on a level road or
downhill grades

with the transmission in neutral
positionN

with the parking brake set

if the ESP® has switched off due to a
malfunctionTowing a trailer
If you tow a trailer, note the following
points:

Manually shift to a lower gear range
(
page 197) if the transmission hunts
between gears on inclines.
A lower gear range and reduction of
speed reduces the chance to overload
or overheat the engine.
For more information on trailer towing, see
the “Operation” section (
page 364).
Gear ranges
With the automatic transmission in drive
positionD, you can select a gear range for
the automatic transmission to operate
within.
You can limit the gear range by pressing
the left gearshift button on the steering
wheel gearshift control, and reverse the
gear range limit by pressing the right gear-
shift button on the steering wheel gearshift
control (
page 198).The selected gear range appears in the
multifunction display.
1Current gear range
Effect
ïThe transmission shifts through
sixth gear only.
îThe transmission shifts through
fifth gear only.
éThe transmission shifts through
fourth gear only.
èThe transmission shifts through
third gear only.
With this selection you can use
the braking effect of the engine.
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201 Controls in detail
Transfer case
Transfer case
LOW RANGE mode*
The LOW RANGE mode is available on vehi-
cles with enhanced off-road package*.
In the following situations you should
switch to LOW RANGE mode:

during off-road driving (page 355)

when crossing water (page 360)

when towing up or down on steep
gradients
With the LOW RANGE selected, the
engine’s power delivery and the shifting
behavior of the automatic transmission are
adjusted. Furthermore, the ABS, ESP
® and
4-ETS functions especially adapted to
off-road travel are activated.
For information on driving safety systems
during LOW RANGE mode, see “Driving
safety systems” (
page 101).
For more information on Off-road driving,
see “Off-road driving” (
page 355).Gear Ranges
There are two possible settings.
!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.
iThe vehicle is equipped with permanent
four-wheel drive. Both the front and rear axles
are powered at all times when the vehicle is
being operated.
HIGH
RANGERoad position for all normal
driving situations.
(LOW RANGE mode off)
LOW
RANGEOff-road position for traveling
on rough terrain.
(LOW RANGE mode on)
Also use the off-road position
when driving on-road on steep
gradients, especially when
towing a trailer.
LOW RANGE acts by raising
the engine’s gear ratio. The ve-
hicle travels at roughly third
the speed compared to when
in the HIGH RANGE position,
leading to an increase in the
engine’s drive power.
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352 Operation
Driving instructions
For more information, see “Tires and
wheels” (
page 384).
Hydroplaning
Depending on the depth of the water layer
on the road, hydroplaning may occur, even
at low speeds and with new tires. Reduce
vehicle speed, avoid track grooves in the
road and apply brakes cautiously in the
rain.
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 winter tires
(
page 420) with a minimum tread depth
of approximately 1/6in (4 mm) on all four
wheels for the winter season to make sure
normal balanced handling characteristics.
On packed snow, they can reduce your
stopping distance compared to 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.
Warning!G
Do not drive with a flat tire. A flat tire affects
the ability to steer or brake the vehicle. You
may lose control of the vehicle. Continued
driving with a flat tire or driving at high
speed with a flat tire will cause excessive
heat build-up and possibly a fire.
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 a drive wheel. This may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
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365 Operation
Driving instructions
Electrical connections
The vehicle is prewired to accept the
seven-wire harness included in the
Mercedes-Benz approved trailer hitch
receiver kit.
For further information, contact an autho-
rized Mercedes-Benz Light Truck Center.
Vehicle and trailer weights and ratings
Gross Vehicle Weight Rating (GVWR) is the
maximum permissible vehicle weight:
6944 lb (3150 kg).
Gross Vehicle Weight (GVW):
Comprises weight of vehicle including fuel,
tools, spare wheel, installed accessories,
passengers, cargo and trailer tongue. It
must never exceed the GVWR.Gross Axle Weight Rating (GAWR) is the
maximum permissible axle weight:
The Gross Trailer Weight (GTW) is the
weight of the trailer plus the weight of all
cargo, equipment, luggage etc. loaded on
the trailer. The maximum permissible
gross trailer weight to be towed:
7500 lb (3402 kg).
Trailer Tongue Weight Rating (TWR) is the
maximum permissible weight on the trailer
tongue:
600 lb (272 kg) limit for Mercedes-Benz
approved hitch receiver.Loading a trailer

When loading a trailer, you should ob-
serve that neither the permissible GTW,
nor the GVWR are exceeded.
Maximum permissible values are listed
on the safety compliance certification
labels for the vehicle and for the trailer
to be towed.
The lowest value listed must be select-
ed when determining how the vehicle
and trailer are loaded.

The tongue weight at the hitch ball
must be added to the GVW to prevent
exceeding your Mercedes-Benz tow
vehicle’s rear GAWR.
iA four-pole conversion plug is available from
your authorized Mercedes-Benz Light Truck
Center as a spare part.
GL 320 CDI
Front3306 lb (1500 kg)
Rear3968 lb (1800 kg)
GL 450, GL 550
Front3240 lb (1470 kg)
Rear3968 lb (1800 kg)
iWe recommend loading the trailer in such a
manner that it has a Tongue Weight (TW)
between 8% and 15% of the Gross Trailer Weight
(GTW).
iMaximum trailer weight ratings are calculat-
ed assuming the vehicle, plus driver. The weight
of other accessories, passengers and cargo will
reduce the maximum trailer weight and Tongue
Weight (TW) your vehicle can tow.
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397 Operation
Tires and wheels
Restarting the Run Flat Indicator
The Run flat indicator must be restarted in
the following situations:

If you have changed the tire inflation
pressure

If you have replaced the wheels or tires

If you have installed new wheels or
tires
Using the Tire and Loading Information
placard on the driver’s door B-pillar or,
if available, the tire inflation pressure
label on the inside of the fuel filler flap,
make sure the tire inflation pressure of
all four tires is correct.
Switch on the ignition (page 42).
Make sure the standard display menu
appears in the multifunction display
(
page 155).
Press buttonk orj repeatedly
until the following message appears in
the multifunction display:
Press the reset button on the instru-
ment cluster (
page 152).
The following message will appear in
the multifunction display:
Restart
Run Flat Indicator?
Yes
Cancel
Warning!G
The Run Flat Indicator does not provide a
warning for wrongly selected tire inflation
pressures. Always adjust tire inflation pres-
sure according to the Tire and Loading
Information placard on the driver’s door
B-pillar (
page 388) or, if available, on the
tire inflation pressure label located on the
inside of the fuel filler flap (
page 374).
The Run Flat Indicator does not replace
regular checks of the tire inflation pressures
since a gradual pressure loss in more than
one tire cannot be detected by the Run Flat
Indicator.
The Run Flat Indicator is not able to issue a
warning due to a sudden dramatic loss of
tire inflation pressure (e.g. tire blowout
caused by a foreign object). In this case
bring the vehicle to a halt by carefully apply-
ing the brakes and avoiding abrupt steering
maneuvers.
Warning!G
The Run Flat Indicator can only warn you in
a reliable manner if you have set the correct
tire inflation pressures for each tire.
If an incorrect tire inflation pressure was set,
the system will monitor the pressure ac-
cording to the incorrect value.
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398 Operation
Tires and wheels
If you wish to confirm activation:
Press buttonæ.
The following message will appear in
the multifunction display:
Run Flat Indicator
Restarted
After a certain “learning phase”, the Run
Flat Indicator checks the set pressure val-
ues for all four tires.
If you wish to cancel activation:
Press buttonç.
or
Wait until the message
Restart
Run Flat Indicator?
Yes
Cancel
disappears.Checking tire pressure electronically
with the Tire Pressure Monitoring
System (TPMS), (USA only)
The TPMS only functions on wheels that
are equipped with the proper electronic
sensors. It monitors the tire inflation pres-
sure, as selected by the driver, in all four
tires. A warning is issued to alert you to a
decrease in pressure in one or more of the
tires.
iThe Tire Pressure Monitoring System
(TPMS) is equipped with a combination low tire
pressure/TPMS malfunction telltale in the
instrument cluster (
page 27). Depending on
how the telltale illuminates, it indicates a low tire
pressure condition or a malfunction in the TPMS
system itself:

If the telltale illuminates continuously,
one or more of your tires is significantly
underinflated. There is no malfunction in the
TPMS.

If the telltale flashes for 60 seconds and
then stays illuminated, the TPMS system
itself is not operating properly.
iThis device complies with Part 15 of the
FCC Rules. Operation is subject to the following
two conditions:
(1) This device may not cause harmful interfer-
ence, and
(2) this device must accept any interference
received, including interference that may
cause undesired operation.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
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400 Operation
Tires and wheels
Tire inflation pressure warnings
If the system detects a significant loss of
tire inflation pressure in one or more than
one tire, a message appears in the multi-
function display.
Example illustration
In addition, a warning signal sounds.Restarting the TPMS
The TPMS must be restarted when you
have adjusted the tire inflation pressure to
a new level (e.g. because of different load
or driving conditions). The TPMS is then
recalibrated to the current tire inflation
pressures.
Using the Tire and Loading Information
placard on the driver’s door B-pillar
(
page 388) or, if available, the
supplemental tire inflation pressure
information on the inside of the fuel
filler flap (
page 374), make sure the
tire inflation pressure of all four tires is
correct.
TPMS malfunctions may occur for a variety
of reasons, including the installation of in-
compatible replacement or alternate tires or
wheels on the vehicle that prevent the TPMS
from functioning properly. Always check the
TPMS malfunction telltale after replacing
one or more tires or wheels on your vehicle
to ensure that the replacement or alternate
tires and wheels allow the TPMS to continue
to function properly.
iIf a condition causing the TPMS to malfunc-
tion develops, it may take up to 10 minutes for
the system to signal a malfunction using the
TPMS telltale flashing and illumination se-
quence.
The telltale extinguishes after a few minutes driv-
ing if the malfunction has been corrected.
iOperating radio transmission equipment
(e.g. wireless headsets, two-way radios) in or
near the vehicle could cause the TPMS to mal-
function.
Warning!G
It is the driver’s responsibility to calibrate
the TPMS on the recommended cold infla-
tion pressure. Underinflated tires affect the
ability to steer or brake the vehicle. You
might lose control over the vehicle.

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401 Operation
Tires and wheels
Switch on the ignition (page 42).
Press buttonè orÿ on the mul-
tifunction steering wheel repeatedly
until the standard display menu ap-
pears in the multifunction display
(
page 155).
Press buttonj or k repeatedly
until you see the following message:
Tire Pressure Monitor
Active
Menu: R-Button
Press the reset button (page 152).
The following message will appear in
the multifunction display:
Restart tire
pressure monitor?
Press buttonæ.
The following message will appear in
the multifunction display:
Tire Pressure Monitor
Restarted
After driving a few minutes the system
verifies that the current tire inflation
pressures are within the system’s
specified range. Afterwards the current
tire inflation pressures are accepted as
reference pressures and then moni-
tored.
If you wish to cancel activation:
Press buttonç.Checking tire pressure electronically
with the Advanced Tire Pressure Moni-
toring System (Advanced TPMS)*,
(Canada only)
The TPMS only functions on wheels that
are equipped with the proper electronic
sensors. It monitors the tire inflation pres-
sure, as selected by the driver, in all four
tires. A warning is issued to alert you to a
decrease in pressure in one or more of the
tires.
Tire pressure inquiries are made using the
multifunction display. The present inflation
pressures are displayed only after a few
minutes’ travel time.
iRestart the TPMS after adjusting the tire in-
flation pressure to the inflation pressure recom-
mended for the vehicle operating condition. Tire
pressure should only be adjusted on cold tires.
Observe the recommended tire inflation pres-
sure on the Tire and Loading Information placard
on the driver’s door B-pillar (
page 388). Some
vehicles may have supplemental tire inflation
pressure information for driving at high speeds
(
page 394) or for vehicle loads less than the
maximum loaded vehicle condition
(
page 394). If such information is provided, it
can be found on the inside of the fuel filler flap.
iThis device complies with RSS-210 of Indus-
try Canada. Operation is subject to the following
two conditions:
(1) This device may not cause interference, and
(2) this device must accept any interference
received, including interference that may
cause undesired operation of the device.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
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404 Operation
Tires and wheels
Restarting Advanced TPMS*
The TPMS usually recognizes new refer-
ence values automatically, for example
when you have

adjusted the tire inflation pressure

changed wheels or tires

mounted new wheels or tiresIf you want to set new reference values
manually:
Using the Tire and Loading Information
placard on the driver’s door B-pillar
(
page 388) or, if available, the sup-
plemental tire inflation pressure
information on the inside of the fuel
filler flap (
page 374), make sure the
tire inflation pressure of all four tires is
correct.
Press buttonè orÿ on the mul-
tifunction steering wheel repeatedly
until the standard display menu
appears in the multifunction display
(
page 155).
Press buttonj or k repeatedly
until

the current inflation pressures for
each tire appear in the multifunc-
tion display
or

the following message appears in
the multifunction display
Tire pressure
displayed after
driving for
a few minutes.
Press the reset button (page 152).
The following message will appear in
the multifunction display:
Restart tire
pressure monitor?
Warning!G
It is the driver’s responsibility to calibrate
the TPMS on the recommended cold infla-
tion pressure. Underinflated tires affect the
ability to steer or brake the vehicle. You
might lose control over the vehicle.
iReactivate the TPMS after adjusting the tire
inflation pressure to the inflation pressure rec-
ommended for the vehicle operating condition.
Tire pressure should only be adjusted on cold
tires. Observe the recommended tire inflation
pressure on the Tire and Loading Information
placard on the driver’s door B-pillar
(
page 388). Some vehicles may have supple-
mental tire inflation pressure information for
driving at high speeds (
page 394) or for vehi-
cle loads less than the maximum loaded vehicle
condition (
page 394). If such information is
provided, it can be found on the inside of the fuel
filler flap.
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420 Operation
Winter driving
Before the onset of winter, have your
vehicle 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
“MB SummerFit” to a premixed wind-
shield washer solvent/antifreeze
which is formulated for temperatures
below freezing point (
page 569).

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

Tire change. Mercedes-Benz recom-
mends M+S rated radial-ply tires with a
minimum tread depth of approximately
1/6in (4 mm) on all four wheels for the
winter season.
Winter tires
Always use winter tires at temperatures
below 45°F (7°C) and whenever wintry
road conditions prevail. Not all M+S rated
tires provide special winter performance.
Make sure the tires you use show the
mountain/snowflake.marking on the
tire sidewall. These tires meet specific
snow traction performance requirements
of the Rubber Manufacturers Association
(RMA) and The Rubber Association of Can-
ada (RAC) and have been designed specif-
ically for use in snow conditions. Use of
winter tires is the only way to achieve the
maximum effectiveness of the ABS, ESP
®,
4-ETS, and EBP in winter operation.
For safe handling, make sure all mounted
winter tires 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
vehicle, you must place a notice to this
effect where it will be seen by the driver.
Such notices are available from your tire
dealer or from any authorized
Mercedes-Benz Light Truck Center.
Warning!G
Winter tires with a tread depth of less than 1/6in (4 mm) must be replaced. They are no
longer suitable for winter operation.
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