2008 MERCEDES-BENZ GL550 center console

153 Controls in detail
Instrument cluster
Adjusting instrument cluster illumina-
tion
Use button1 or3 to adjust the illumina-
tion brightness for the instrument cluster.
To brighten illumination
Press and hold button3 until the
desired level of illumination is reached.
To dim illumination
Press and hold button1 until the
desired level of illumination is reached.
Resetting trip odometer
Make sure you are viewing the trip odome-
ter display (
page 155).
If it is not displayed, press buttonè
orÿ on the multifunction steering
wheel (
page 156) repeatedly until
the trip odometer appears in the multi-
function display.
Press and hold reset button2 in the
instrument cluster (
page 152) until
the trip odometer is reset.
Tachometer
The red marking on the tachometer
(
page 26) denotes excessive engine
speed.To help protect the engine, the fuel supply
is interrupted if the engine is operated
within the red marking.
Outside temperature indicator
The outside temperature is displayed in the
multifunction display (
page 155).
iThe instrument cluster illumination is
dimmed or brightened automatically to suit am-
bient light conditions.
The instrument cluster illumination will also be
adjusted automatically when you switch on the
vehicle’s exterior lamps.
iWith the exterior lighting switched on, the
brightness of the switches in the center console
will also be adjusted when using button
1 or3.
!Avoid driving at excessive engine speeds, as
it may result in serious engine damage that is not
covered by the Mercedes-Benz Limited
Warranty.
Warning!G
The outside temperature indicator is not de-
signed to serve as an ice-warning device and
is therefore unsuitable for that purpose.
Indicated temperatures just above the freez-
ing point do not guarantee that the road sur-
face is free of ice. The road may still be icy,
especially in wooded areas or on bridges.
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165 Controls in detail
Control system
Operating CD player
Selecting CD track
Turn on the COMAND system and
select CD. Refer to separate COMAND
system operating instructions.
Press buttonè orÿ repeatedly
until the settings for the CD currently
being played appear in the multifunc-
tion display.1Current CD (for CD changer)
2Current track
Press buttonk orj repeatedly
until the desired track is selected.Selecting MP3-CD track
Turn on the COMAND system and se-
lect MP3. Refer to separate COMAND
system operating instructions.
Press buttonè orÿ repeatedly
until the settings for the MP3-CD
currently being played appear in the
multifunction display.
1MP3 mode
2Current track
Press buttonk orj repeatedly
until the desired track is selected.
iAdditional optional satellite radio equipment
and a subscription to satellite radio service pro-
vider are required for satellite radio operation.
Contact an authorized Mercedes-Benz Light
Truck Center for details and availability for your
vehicle.
For more information, refer to separate
COMAND system operating instructions.
iTo select a CD from the CD changer
magazine, press a number on the COMAND
system key pad located in the center console.
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202 Controls in detail
Transfer case
Switching LOW RANGE mode
The switch is located on the upper part of
the center console.
1LOW RANGE switch
2Indicator lamp
3LOW RANGE displaySwitching LOW RANGE mode on
(switching from HIGH RANGE to LOW
RANGE)
Press LOW RANGE switch1.
Indicator lamp2 flashes.
If the system senses that all conditions
are met, it will switch to LOW RANGE
mode. A chime sounds and the LOW
RANGE display3 appears in the multi-
function display.
The indicator lamp2 on the
LOW RANGE switch comes on continu-
ously, indicating that the LOW RANGE
mode has been activated.
Warning!G
Always wait until the procedure of shifting
from HIGH RANGE to LOW RANGE – and
from LOW RANGE to HIGH RANGE – has
been entirely completed. During this proce-
dure do not:

switch off the engine

shift the automatic transmission into
another gear
If you do not wait until the shifting proce-
dure has been entirely completed then it
might not be correctly performed. The trans-
fer case might be in neutral, thus interrupt-
ing the transfer of power between the
engine and the drive axle.
The vehicle is then freely movable, even if a
gear has been selected, and could uninten-
tionally be set into motion – particularly on
up – or downhill grades. This could lead to
an accident and cause injury to yourself and
others.
Please observe related messages appearing
in the multifunction display (
page 488).
!The shift procedure can only be performed
when the following conditions are met:

The engine is running (page 41).

The automatic transmission is in positionN
(
page 190).

The vehicle speed does not exceed 25 mph
(40 km/h).
iThere is no reset to HIGH after the ignition
has been switched off.
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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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205 Controls in detail
Differential locks*
at the same speed, independent of the in-
dividual torque. Please be aware that en-
gaging the differential locks will
significantly reduce the steering ability of
the vehicle.
For your safety and the safety of others
and to prevent damage to the vehicle, the
differential locks must not be engaged
when driving on paved roads. It is impor-
tant to understand that during
on-road/paved driving, differentials are
absolutely necessary for providing the es-
sential control and steering ability of the
vehicle. The differential locks, therefore,
must not be engaged when driving on
paved roads and should only be used to
the extent necessary to negotiate off-road
conditions which cannot be handled by the
systems (automatic 4-ETS, the ESP
®, man-
ual switch position “LOW” of transfer case)
this vehicle comes equipped with.
Switching differential locks*The rotary switch for the differential locks
is located on the upper part of the center
console.
You can select between three locking
modes.
1Rotatable outer adjustment ring with
indicator lamp
2AUTO mode: center differential is auto-
matically locked
3Center differential is completely locked
4Center and rear axle differential are
completely locked
!If the differential locks are engaged, accel-
erate gently when setting the vehicle in motion.
To avoid damage to the transmission, the vehicle
may only be operated on a dynamometer (single
axle dynamometer) if

the axle not being driven is jacked up
or

the associated propeller shaft is disconnect-
ed.
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226 Controls in detail
Climate control
Rear climate control*
The control panel is located on the rear of
the front center console.
Activating rear climate control
Press buttonU.
The indicator lamp on the button
comes on. The air volume and air distri-
bution are adjusted automatically.Deactivating rear climate control
Press button´.
The indicator lamp on the button
comes on.
The cooling function switches off after
a short delay.iThe rear climate control panel is only
available if your vehicle is equipped with seat
heating* for the rear seats or Rear Audio fea-
ture* (see separate COMAND System operating
instructions).
1Left rear center air vent, adjustable
2Right rear center air vent, adjustable
3Rear climate control on
(automatic mode)
4Air distribution (directs air through
the center air vents)
5Air distribution (directs air through
the footwells and side air vents)
6Rear air conditioning off
iThe climate control must be switched on
(
page 227).
iThe temperature is adjusted according to
the settings for the front passenger side made
on the front climate control panel (
page 219).
iSwitch off the rear climate control for im-
proved cooling or heating output in the front pas-
senger compartment.
You can also switch off the rear climate control
from the front passenger compartment
(
page 227).
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241 Controls in detail
3-zone automatic climate control*
Residual heat and ventilation
With the engine switched off, it is possible
to continue to heat or ventilate the interior
for up to 30 minutes. This feature makes
use of the residual heat produced by the
engine.Activating
Switch off the ignition (page 41).
Press button9 (page 230).
The indicator lamp on the button
comes on.
Deactivating
Press button9.
The indicator lamp on the button goes
out.
Rear automatic climate control
The control panel is located at the rear of
the front center console.
iHow long the system will provide heating
depends on

the coolant temperature

the battery voltage
Regardless of the temperature and air volume
set on the automatic climate control panel, an
interior temperature is aimed at by 72°F (22°C)
and the blower runs on low speed to protect the
vehicle battery.
iThe residual heat is automatically turned off:

when the ignition is switched on

after about 30 minutes

if the coolant temperature is too low

if the battery voltage drops
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274 Controls in detail
Driving systems
Switching the Downhill Speed
Regulation on/off
The switch is located on the upper part of
the center console.
Vehicles without enhanced off-road
package*
1DSR on/off
2Indicator lamp
Vehicles with enhanced off-road package*
1DSR on/off
2Indicator lamp
iWhenever DSR is switched on, DSR will use
the programmed default speed to regulate the
vehicle’s speed. The default speed programmed
at the factory is 4 mph (Canada: 6 km / h). The
default speed can be reprogrammed using the
control system (
page 183). The next time DSR
is switched on, DSR will use the newly pro-
grammed default speed to regulate the vehicle’s
speed.
Once DSR is switched on, you can adjust the set
speed using the cruise control lever
(
page 265). Keep in mind that adjusting the
set speed using the cruise control lever with DSR
switched on will not change the programmed
default speed. If DSR is switched off and then
switched on again, DSR will use the programmed
default speed.
Depending on the road surface and level of
downhill grade, the DSR may not be able to
maintain the set speed. To maintain the set
speed, apply the brakes if necessary.
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