2008 MERCEDES-BENZ GL320 light

200 Controls in detail
Automatic transmission
Emergency operation (Limp-Home
Mode)
If vehicle acceleration becomes less re-
sponsive or sluggish or the transmission
no longer shifts, the transmission is most
likely operating in limp-home (emergency
operation) mode. In this mode only second
gear and reverse gear can be activated.
Stop the vehicle in a safe location.
Shift to park positionP.
Turn off the engine.
Wait at least 10 seconds before
restarting.
Restart the engine.
Shift to drive positionD (for second
gear) or reverse gearR.
Have the transmission checked at an
authorized Mercedes-Benz Light Truck
Center as soon as possible.
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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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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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208 Controls in detail
Good visibility
For information on windshield wipers, see
“Windshield wipers” (
page 62).
Headlamp cleaning system*
The headlamps will automatically be
cleaned with a high-pressure water jet
when you have

switched on the headlamps
and

operated the windshield wipers with
windshield washer fluid five times
When you switch off the headlamps, the
counter resets.
For information on filling up the washer
reservoir, see “Windshield/rear window
washer system and headlamp cleaning
system*” (
page 383).
Rear view mirrors
For more information on setting the rear
view mirrors, see “Mirrors” (
page 51).
Interior rear view mirror, antiglare
position
1Lever
Tilt the mirror to the antiglare position
by moving lever1 towards the wind-
shield.
The interior rear view mirror is dimmed.Auto-dimming rear view mirrors*
The reflection brightness of the exterior
rear view mirror on the driver’s side and
the interior rear view mirror will respond
automatically to glare when

the ignition is switched on
and

incoming light from headlamps falls on
the sensor in the interior rear view
mirror
The rear view mirror will not react if

the automatic transmission is set to
positionR

the interior lighting is turned on
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209 Controls in detail
Good visibility
Power folding exterior rear view
mirrors*
Folding the exterior rear view mirrors
in and out automatically
When the corresponding function in the
control system is activated (
page 182):

The exterior rear view mirrors automat-
ically fold in as soon as the vehicle is
locked from the outside.

The exterior rear view mirrors automat-
ically fold out as soon as the vehicle is
unlocked and the driver’s or front pas-
senger door are subsequently opened.Synchronizing exterior rear view
mirrors
The power folding rear view mirrors may
have to be synchronized after the vehicle
battery has been disconnected or dis-
charged. If the exterior rear view mirrors
do not fold properly upon locking or un-
locking the vehicle although the corre-
sponding function in the control system is
activated (
page 182), do the following:
Fold each exterior rear view mirror in
completely (
page 210).
Fold each exterior rear view mirror out
completely (
page 210).
When the exterior rear view mirrors fold
properly upon locking the vehicle, the exte-
rior mirrors are synchronized. Otherwise
repeat the above steps.
Warning!G
The auto-dimming function does not react if
incoming light is not aimed directly at sen-
sors in the interior rear view mirror.
The interior rear view mirror and the exterior
rear view mirror on the driver’s side do not
react, for example, when transporting cargo
which covers the rear window.
Light hitting the mirror(s) at certain angles
(incident light) could blind you. As a result,
you may not be able to observe traffic con-
ditions and could cause an accident.
Warning!G
Exercise care when using the passen-
ger-side exterior rear view mirror. The mirror
surface is convex (outwardly curved surface
for a wider field of view). Objects in mirror
are closer than they appear. Check your
interior rear view mirror or glance over your
shoulder before changing lanes.
!Before you drive the vehicle through an
automatic car wash, fold the exterior rear view
mirrors in. Otherwise they may get damaged.
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217 Controls in detail
Climate control
The climate control is operational whenev-
er the engine is running. You can operate
the climate control system in either the
automatic or manual mode. The system
cools or heats the interior depending on
the selected interior temperature and the
current outside temperature.Nearly all dust particles, pollutants and
odors are filtered out before outside air en-
ters the passenger compartment through
the air distribution system.
The air conditioning will not engage (no
cooling) if the A/C mode is deactivated
(
page 224).
Warning!G
When operating the climate control, the air
that enters the passenger compartment
through the air vents can be very hot or very
cold (depending on the set temperature).
This may cause burns or frostbite to unpro-
tected skin in the immediate area of the air
vents.
Always keep sufficient distance between un-
protected parts of the body and the air
vents. If necessary, use the air distribution
controls (
page 216) to direct the air to air
vents in the vehicle interior that are not in
the immediate area of unprotected skin.
Warning!G
Severe conditions (e.g. strong air pollution)
may require replacement of the filter before
its scheduled interval. A clogged filter will
reduce the air volume to the interior and the
windows could fog up, impairing visibility
and endangering you and others. Have a
clogged filter replaced as soon as possible
at an authorized Mercedes-Benz Light Truck
Center.
Warning!G
Follow the recommended settings for heat-
ing and cooling given on the following pag-
es. Otherwise the windows could fog up,
impairing visibility and endangering you and
others.
iIf the vehicle interior is hot, ventilate the in-
terior before driving off, see “Summer opening
feature” (
page 249). The climate control will
then adjust the interior temperature to the set
value much faster.
Keep the air intake grille in front of the wind-
shield free of snow and debris.
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219 Controls in detail
Climate control
or
Press air distribution button5,9,
ora (
page 216).
The indicator lamp on buttonU
goes out. The automatic operation of
air distribution switches off.
Setting the temperature
Use temperature controls1 and7
(
page 216) to separately adjust the air
temperature on each side of the passenger
compartment. You should raise or lower
the temperature setting in small incre-
ments, preferably starting at 72°F (22°C).
The climate control will adjust to the set
temperature as fast as possible.Increasing
Turn temperature control1
and/or7 (
page 216) slightly clock-
wise.
The climate control system will corre-
spondingly adjust the interior air tem-
perature.
Decreasing
Turn temperature control1
and/or7 (
page 216) slightly coun-
terclockwise.
The climate control system will corre-
spondingly adjust the interior air tem-
perature.
Adjusting air distribution
Press air distribution button5,9, ora
(
page 216) to adjust the air distribution.
The following symbols are found on the
controls:
Press the desired air distribution
button5,9, ora (
page 216).
The indicator lamp on buttonU
goes out.
SymbolFunction
aDirects air through the center
and side air vents
ZDirects air to the windshield
and side air vents
YDirects air to the footwells and
side air vents
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221 Controls in detail
Climate control
Adjusting air distribution
Move air vent slider2 to the left, right,
up, or down to direct the air in the de-
sired direction.
Front defroster
You can use this setting to defrost the
windshield, for example if it is iced up. You
can also use it to defog the windshield and
door windows.
Activating
Press button| (page 216).
The indicator lamp on the button
comes on.The climate control switches to the follow-
ing functions automatically:

most efficient blower speed and
heating power, depending on outside
temperature

air flows onto the windshield and the
door windows (side air vents must be
open)

the air conditioning compressor
switches on at outside temperatures
above approximately 41°F (5°C) for
air-drying
Adjustments
You can adjust the air volume and the tem-
perature when the front defroster is
switched on. The air flow will remain on the
windshield and door windows.
Press button
to decrease or
buttonQ to increase air volume
(
page 216) to the desired level.The air volume decreases/increases to
the next lower/higher blower speed
and heating switches to the tempera-
ture that was set before the front de-
froster was switched on.
The indicator lamp on button|
goes out. The indicator lamp on
button9 comes on.
or
Turn temperature control1
and/or7 (
page 216) slightly in any
direction.
Heating switches to the temperature
that was set before the front defroster
was switched on.
The indicator lamp on button|
goes out. The indicator lamp on
button9 comes on.iKeep this setting selected only until the
windshield or the door windows are clear again.
iThe air conditioning compressor remains on
even if the indicator lamp in button| goes
out. This helps to prevent the windshield from
fogging.
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