2008 MERCEDES-BENZ GL320 wheel

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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206 Controls in detail
Differential locks*
AUTO mode
The AUTO mode is adequate for most driv-
ing situations since the center differential
is locked and released as required.
Start the engine (page 42).
The center differential locks is in AUTO
mode. The indicator lamp on the
adjustment ring1 above
symbolU2 is on.Center and rear axle differential locksThe differential locks should only be
engaged manually if traction is insufficient
in AUTO mode.
The differential locks can be engaged in
the sequence3, 4 (
page 205) up to a
speed of 19 mph (30 km/h).
Engaging differential locks:

for off-road driving

for driving through water

when driving on deep snow and icy or
fouled surfaces
iAt speeds up to 19 mph (30 km/h), it is
possible to manually lock the differential locks
for driving on rough terrain.
Warning!G
Never drive on a paved surface with the
center and rear axle differential locks
manually engaged. Ability to steer the
vehicle is greatly reduced when the differen-
tial locks are manually engaged, increasing
the risk of an accident.
For safety reasons, the locks are automati-
cally released at a vehicle speed above
31 mph (50 km/h). Nevertheless, you
should only manually lock the differential if
absolutely necessary because engaged
locks will restrict the vehicle drive train
while cornering and cause the vehicle to
chatter. This could cause you to lose control
of the vehicle and cause an accident.
!The differential locks must not be engaged
manually when towing the vehicle or spinning the
wheels.
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207 Controls in detail
Differential locks*
Start the engine (page 42).
To select the required locking mode,
rotate adjustment ring2 to the
desired position3 or4
(
page 205).
The indicator lamp on the adjustment
ring1 at the respective symbol
comes on.
Example illustration
5Center differential is completely locked
!If the differential locks have been manually
engaged, the tires will scuff on the road surface
when cornering because the differences be-
tween the individual wheel rotation speeds will
not be compensated for.
iThe differential locks are reset to AUTO
mode after the ignition has been switched off for
longer than 10 seconds.
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215 Controls in detail
Climate control
1Driver’s door air vent, fixed
2Left side air vent, adjustable
3Thumbwheel for air volume control
for left side and door air vent
4Windshield air vents
5Thumbwheel for air volume control
for left center air vent
6Left center air vent, adjustable
7Right center air vent, adjustable
8Thumbwheel for air volume control
for right center air vent
9Thumbwheel for air volume control
for right side and door air vent
aRight side air vent, adjustable
bFront passenger door air vent, fixed
cClimate control panel
dFootwell air vents
iFor draft-free ventilation, move the sliders
for center air vents and side air vents to the
middle position.
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220 Controls in detail
Climate control
Adjusting air volume
Five blower speeds are available.
Press button
to decrease or
buttonQ to increase air volume
(
page 216) to the desired level.
The indicator lamp on buttonU
(
page 216) goes out. The automatic
operation of air volume switches off.
The selected blower speed is shown in
the air volume displayb
(
page 216).
Adjusting air volume for the center and
side air vents
Opening the center air vents
Turn thumbwheels5 and8
(
page 214) to the right.
The corresponding center air vents on
the left and right are open.Closing the center air vents
Turn thumbwheels5 and8
(
page 214) to the left.
The corresponding center air vents on
the left and right are closed.
Opening the side air vents
Turn thumbwheels3 andb
(
page 214) to the right.
The corresponding side air vents on the
left and right are open.
Closing the side air vents
Turn thumbwheels3 andb
(
page 214) to the left.
The corresponding side air vents on the
left and right are closed.Air vents in the roof liner over the
second-row seats*
1Thumbwheel for air volume control
2Air vent, adjustable
Adjusting air volume
Turn thumbwheel1 d o w n t o d e c r e a s e
the air volume.
or
Turn thumbwheel1 up to increase the
air volume.
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229 Controls in detail
3-zone automatic climate control*
1Driver’s door air vent, fixed
2Left side air vent, adjustable
3Thumbwheel for air volume control
for left side and door air vent
4Windshield air vents
5Thumbwheel for air volume control
for left center air vent
6Left center air vent, adjustable
7Right center air vent, adjustable
8Thumbwheel for air volume control
for right center air vent
9Thumbwheel for air volume control
for right side and door air vent
aRight side air vent, adjustable
bFront passenger door air vent, fixed
cAutomatic climate control panel
dFootwell air vents
iFor draft-free ventilation, move the sliders
for center air vents and side air vents to the
middle position.
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234 Controls in detail
3-zone automatic climate control*
Setting the temperature
Use temperature control1 and9
(
page 230) 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 automatic climate control will adjust to
the set temperature as fast as possible.
Increasing
Turn temperature control1
and/or9 slightly clockwise.
The automatic climate control system
will correspondingly adjust the interior
air temperature.
Decreasing
Turn the temperature control1
and/or9 slightly counterclockwise.
The automatic climate control system
will correspondingly adjust the interior
air temperature.
Adjusting air distribution
Use the air distribution controls3,h,
orj for the driver’s side, or7,b, orc
(
page 230) for the passenger side to
separately adjust the air distribution on
each side of the passenger compartment.
The following symbols are found on the
buttons:
Press the desired air distribution but-
ton (
page 230).
The indicator lamp on the desired but-
ton goes out.
Adjusting the air distribution for the
center and side air vents
Opening the center air vents
Turn thumbwheels5 and8
(
page 228) to the right.
The corresponding center air vents on
the left and right are open.
Closing the center air vents
Turn thumbwheels5 and8
(
page 228) to the left.
The corresponding center air vents on
the left and right are closed.
SymbolFunction
Driver’s
sidePassen-
ger side
6ZDirects air to the
windshield and side
air vents
7aDirects air through
the center, side and
rear passenger
compartment air
vents
8YDirects air to the
footwells and side
air vents
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