ABS MERCEDES-BENZ GL550 2008 X164 User Guide

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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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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255 Controls in detail
Driving systems
Driving systems
The driving systems of your vehicle are
described on the following pages:

Cruise control (page 255) and
Distronic* (
page 260), with which
the vehicle can maintain a preset
speed.

Distance warning function*
(
page 272) is only available with
Distronic*, which warns of stationary
obstacle or slower moving vehicles that
you are closing in on too quickly.

Downhill Speed Regulation (DSR)
(
page 273), which supports you
when you are driving downhill.

Off-road driving program (page 277)
(vehicles without enhanced off-road
package*), which supports you when
you are driving off-road.

Air suspension program
There are two components available.

Vehicle level control (page 279),
which controls the vehicle level.

Adaptive Damping System (ADS)*
(
page 278), which adjusts the
vehicle suspension characteristics.

Parktronic* (page 288) and rear view
camera* (
page 293), which serve as
a parking aid.
For information on the ABS, BAS, EBP,
ESP
®, and 4-ETS, see “Driving safety sys-
tems” (
page 101).
Cruise control
The cruise control automatically maintains
the speed you set for your vehicle.
The use of cruise control is recommended
for driving at a constant speed for extend-
ed periods of time. You can set or resume
cruise control at any speed above
20 mph (30 km/h).
The cruise control function is operated by
means of the cruise control lever.
The cruise control lever is the uppermost
lever on the left-hand side of the steering
column (
page 24).
iThe cruise control should not be activated
during off-road driving.
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277 Controls in detail
Driving systems
Adjustment in 5 mph
(Canada: 10 km/h) increments
Increase set speed:
Briefly lift the cruise control lever up
past the resistance point in direction of
arrow1 (
page 276).
Release the cruise control lever.
The vehicle speed increases in incre-
ments of 5 mph (Canada: 10 km/h).
Reduce set speed:
Briefly press the cruise control lever
down past the resistance point in direc-
tion of arrow2 (
page 276).
Release the cruise control lever.
The vehicle speed decreases in incre-
ments of 5 mph (Canada: 10 km/h).
Each time the set speed is changed,
DSR will appear in the multifunction dis-
play and the newly set speed is shown.Off-road driving program (Vehicles
without enhanced off-road package*)
The off-road driving program is designed to
assist the driver when driving off-road in
terrain and crossing water. The off-road
driving program adjusts the engine power
and shifting of the automatic transmission
to be more suitable for the off-road use of
the vehicle. In addition, the ABS, ESP
®, and
4-ETS designed for off-road use are
automatically activated.
In the following situations you should
switch to the off-road driving program:

during off-road driving

when crossing water (page 360)

when towing up or down on steep
gradients
iThe set value is increased or decreased in
5 mph (Canada: 10 km/h) increments each time
you lift or depress the cruise control lever past
the resistance point.
iThe new speed is set and the vehicle will
accelerate or decelerate. Keep in mind that it
may take a brief moment until the vehicle has
reached the new set speed.
iThe set speed is canceled when DSR is
switched off. If DSR is switched on again, DSR
will use the programmed default speed
(
page 183).
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347 Operation
Driving instructions
Driving instructions
Drive sensibly – save fuel
Fuel consumption, to a great extent,
depends on driving habits and operating
conditions.
To save fuel you should:

Keep tires at the recommended infla-
tion pressures.

Remove unnecessary loads.

Remove carriers* when not in use.

Remove the crossbars* when not in
use.

Allow engine to warm up under low
load use.

Avoid frequent acceleration and decel-
eration.

Have all maintenance work performed
at the intervals specified in the
Maintenance Booklet and as required
by the Maintenance System. Contact
an authorized Mercedes-Benz Light
Truck Center.Fuel consumption is also increased by
driving in cold weather, in stop-and-go traf-
fic, on short trips and in hilly areas.
Drinking and driving
Pedals
Warning!G
Drinking and driving and/or taking drugs
and driving are a very dangerous combina-
tion. Even a small amount of alcohol or
drugs can affect your reflexes, perceptions
and judgment.
The possibility of a serious or even fatal
accident are greatly increased when you
drink or take drugs and drive.
Do not drink or take drugs and drive or allow
anyone to drive who has been drinking or
taking drugs.
Warning!G
Make sure that absolutely no objects are ob-
structing the pedal’s range of movement.
Keep the driver’s footwell clear of all obsta-
cles. If there are any floormats or carpets in
the footwell, make sure that the pedals still
have sufficient clearance.
During sudden driving or braking maneu-
vers, the objects could get caught between
the pedals. You could then no longer brake
or accelerate. This could lead to accidents
and injury.
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354 Operation
Driving instructions
Road salts and chemicals can adversely af-
fect braking efficiency. Increased pedal
force may become necessary to produce
the normal brake effect.
Depressing the brake pedal periodically
when traveling at length on salt-strewn
roads can bring road-salt-impaired braking
efficiency back to normal.If the vehicle is parked after being driven
on salt-treated roads, the braking efficien-
cy should be tested as soon as possible af-
ter driving is resumed.
For more information, see “Winter driving”
(
page 420).
Warning!G
On slippery road surfaces, never downshift
in order to obtain braking action. This could
result in drive wheel slip and reduced vehi-
cle control. Your vehicle’s ABS will not pre-
vent this type of control loss.
Do not engage the transfer case in position
LOW when driving on ice or packed snow. At
speeds below 18 mph (30 km/h) vehicle
steering is adversely affected by the
Off-road – ABS (
page 102).
Warning!G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Warning!G
If the vehicle becomes stuck in snow, make
sure that snow is kept clear of the exhaust
pipe and from around the vehicle with the
engine running. Otherwise, deadly carbon
monoxide (CO) gases may enter vehicle in-
terior resulting in unconsciousness and
death.
To assure sufficient fresh air ventilation,
open a window slightly on the side of the ve-
hicle not facing the wind.
Warning!G
The outside temperature indicator is not de-
signed to serve as an ice-warning device and
is therefore unsuitable for that purpose. In-
dicated temperatures just above the freez-
ing point do not guarantee that the road
surface is free of ice.
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356 Operation
Driving instructions
Read this chapter carefully before you be-
gin off-road travel.
Familiarize yourself with the vehicle char-
acteristics and gear changing before you
attempt any difficult terrain off-road driv-
ing. We recommend that you start out with
easy off-road travel.Special driving features for off-road
driving
The following driving features are available
for specific kind of operation:

Off-road – ABS (page 102)

Off-road – ESP® (page 106)

Off-road – 4-ETS (page 108)

Hill start assist system (page 196)

LOW RANGE mode* (page 201)

Differential locks* (page 204)

Downhill Speed Regulation (DSR)
(
page 273)

Off-road driving program (Vehicles
without enhanced off-road package*)
(
page 277)

Air suspension (page 278)Off-road driving rules

Engage the off-road driving program
(
page 277) or LOW RANGE mode*
(
page 201) before driving under
off-road conditions.

If necessary, activate differential
locks* (
page 204).

Make sure you select a vehicle level
(
page 279) appropriate to the topo-
graphical conditions. Always make
sure the vehicle has enough ground
clearance.

Fasten items being carried as securely
as possible (
page 295).

Always navigate gradients with the en-
gine on and with the transmission en-
gaged in a gear. Switch on the DSR
(
page 274) to help maintain a preset
speed.
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360 Operation
Driving instructions
Driving downhill

Drive slowly.

Do not drive at an angle to the incline.
Steer into the line of gravity and drive
with the front wheels pointing straight
downhill. Otherwise, the vehicle may
slide sideways off the path and roll
over.

Shift automatic transmission to
position1 (
page 197).

On steep inclines, use the Downhill
Speed Regulation (
page 273).

Utilize the engine’s braking power to
reduce vehicle speed.
If this is insufficient, apply the brake
gently. Make sure the vehicle is moving
in the line of gravity.

Check the brakes after a lengthy down-
grade drive.Driving through water
1Fording depth

Before driving through water, deter-
mine its depth.
iThe special Off-road – ABS (page 102)
setting allows for precise and brief (cyclical)
blocking of the front wheels, permitting them to
dig into loose ground.
Remember that, when stopped, the front wheels
slide across a surface and thus lose their ability
to steer the vehicle.Vehicles with air
suspension
program1
Raised level20.00 in (50 cm)
Vehicles with
enhanced off-road
package*1
Off-road 3 level23.60 in (60 cm)
Off-road 2 level20.00 in (50 cm)
Off-road 1 level20.00 in (50 cm)
!The water depth must not exceed the
respective value listed in the table. The ground
under the water might not be firm which could
result the water being deeper than expected
when driving the vehicle through it. Please note
that the water level is correspondingly lower for
flowing water.
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410 Operation
Tires and wheels
Load identification
1Load identificationIn addition to tire load rating, special load
identification1 may be molded into the
tire sidewall following the letter designat-
ing the tire speed rating (
page 406).
No specification given: absence of any text
(like in above example) indicates a
standard load (SL) tire.
XL or Extra Load: designates an extra load
(or reinforced) tire.
Light Load: designates a light load tire.
C, D, E: designates load range associated
with the maximum load a tire can carry at
a specified pressure.
DOT, Tire Identification Number (TIN)
U.S. tire regulations require each new tire
manufacturer or tire retreader to mold a
TIN into or onto a sidewall of each tire
produced.
The TIN is a unique identifier which facili-
tates efforts by tire manufactures to notify
purchasers in recall situations or other
safety matters concerning tires and gives
purchasers the means to easily identify
such tires.
The TIN is comprised of “Manufacturer’s
identification mark”, “Tire size”, “Tire type
code” and “Date of manufacture”.
iFor illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
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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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