2008 MERCEDES-BENZ GL550 heating

349 Operation
Driving instructions
To help prevent brake disk corrosion after
driving on wet road surfaces (particularly
salted roads), it is advisable to brake the
vehicle with considerable force prior to
parking. The heat generated serves to dry
the brakes.
If your brake system is normally only sub-
jected to moderate loads, you should occa-
sionally test the effectiveness of the
brakes by applying above-normal braking
pressure at higher speeds. This will also
enhance the grip of the brake pads.
Refer to the description of the Brake Assist
System (BAS) (
page 103).Brake pad wear or a leak in the system may
be the reason for low brake fluid in the
reservoir.
The brake fluid level in the reservoir may
be too low if the brake warning lamp in the
instrument cluster comes on and an
acoustic warning sounds although the
parking brake is released (
page 437).
Observe additional messages in the multi-
function display that may appear
(
page 469).
Have the brake system inspected
immediately. Contact an authorized
Mercedes-Benz Light Truck Center.
All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact an authorized
Mercedes-Benz Light Truck Center.
Only install brake pads and brake fluid
recommended by Mercedes-Benz.
After hard braking, it is advisable to drive
on for some time, rather than immediately
park, so that the air stream will cool down
the brakes faster.
Warning!G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Warning!G
If other than recommended brake pads are
installed, or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that
safe braking is substantially impaired. This
could result in an accident.
!When driving down long and steep grades,
relieve the load on the brakes by shifting into a
lower gear to use the engine’s braking power.
This helps prevent overheating of the brakes and
reduces brake pad wear.
When using the engine’s braking power, a drive
wheel may not spin for an extended period of
time, e.g. on slippery road surfaces. This may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
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368 Operation
Driving instructions

Always secure items in the trailer to
prevent load shifts while driving.

When towing a trailer, check occasion-
ally to make sure the load is secure,
and that lighting and trailer brakes (if
so equipped) are functioning properly.

Take into consideration that when tow-
ing a trailer, the handling characteris-
tics are different and less stable from
those when operating the vehicle with-
out a trailer.
It is important to avoid sudden maneu-
vers.

The vehicle and trailer combination is
heavier, and therefore is limited in ac-
celeration and climbing ability, and re-
quires longer stopping distances.
It is more prone to reacting to cross
wind gusts, and requires more sensi-
tive steering input.

If possible, do not brake abruptly, but
rather engage the brake slightly at first
to permit the trailer to activate its
brake. Then increase the braking force.

If the transmission repeatedly shifts
between gears on inclines, manually
shift to a lower gear (select 4, 3, 2 or 1)
(
page 197).
A lower gear and reduction of speed re-
duces the chance of engine overload-
ing and/or overheating.

On very steep inclines, not manageable
with automatic transmission in1,
switch on off-road driving program
(
page 278) or LOW RANGE mode*
(
page 201).

When going down a long hill, shift into
a lower gear and use the engine’s brak-
ing effect.
Avoid riding the brakes, thus overheat-
ing the vehicle and trailer brakes.

If the engine coolant rises to an ex-
tremely high temperature (coolant tem-
perature needle approaching the red
zone) when the air conditioning is on,
turn off the air conditioning system.
Engine coolant heat can be additionally
vented by opening the windows,
switching the climate control fan speed
to high and setting the temperature
control to the maximum hot position.

Extreme care must be exercised since
your vehicle with a trailer will require
additional passing distance ahead than
when driving without a trailer.
Because your vehicle and trailer is
longer than your vehicle alone, you will
also need to go much farther ahead of
the passed vehicle before you can re-
turn to your lane.
!If the trailer should begin to sway, reduce
the vehicle’s speed immediately.
In no case attempt to straighten out the tow
vehicle and trailer by increasing the speed.
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376 Operation
At the gas station
Low outside temperatures
(diesel engine)
To prevent malfunctions, diesel fuel with
improved cold flow characteristics is of-
fered in the winter months. Check with
your fuel retailer.Check regularly and before a long trip
Open the hood (page 378).
Example illustration GL 450 (GL 320 CDI,
GL 550 similar)
1Brake fluid
2Coolant level
3Windshield washer system and
headlamp cleaning system*
Engine oil level
For more information on engine oil, see
“Engine oil” (
page 380).
iDiesel engine:
If you have driven the vehicle until the tank is
empty, the fuel system needs to be bled
(
page 527).
!Diesel engine:
The engine is more susceptible to wear and
damage if you use

marine diesel fuel

heating oil

additives
The exhaust aftertreatment device will be
seriously damaged if you use

LOW SULFUR HIGHWAY DIESEL FUEL
(500 ppm SULFUR MAXIMUM)

any other diesel fuel with a sulfur content of
above 15 ppm
The use of such non-approved fuels and/or
special additives is not covered by the
Mercedes-Benz Limited Warranty.
!Do not fill the tank with gasoline. Do not
blend diesel fuel with gasoline or kerosine. The
fuel system and engine will otherwise be dam-
aged, which is not covered by the
Mercedes-Benz Limited Warranty.

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458 Practical hints
What to do if …
Display messagePossible cause/consequencePossible solution
ESPUnavailable
See Operator’s ManualThe ESP® was deactivated because
of insufficient power supply. The
charging voltage has fallen below
10 volts.
The brake system is still functioning
normally but without the ESP
®
available.
When the voltage is above this value again, the
ESP® is operational again and the message in
the multifunction display should disappear.
If the message in the multifunction display does
not disappear:
Have the generator (alternator) and the
battery checked.
Have the system checked at an authorized
Mercedes-Benz Light Truck Center as soon
as possible.
If the yellow ESP® warning
lampv flashes while driving and
this message appears, the 4-ETS has
switched off to prevent overheating
of the drive wheel brakes.As soon as the brakes have cooled off, the
4-ETS switches on again.
The message in the multifunction display disap-
pears and the ESP
® warning lampv goes
out.
The self-diagnosis has not been
completed yet.The display will clear after driving a short
distance at a vehicle speed of above
12 mph (20 km/h).
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580 Index
Headlamps
Automatic headlamp mode 144
Bi-Xenon* 477, 508
Cleaning lenses 429
Cleaning system* 208, 383
Halogen 507
High beam see High beam flasher
High beam see High beam headlamps
Light sensor, Messages in the
multifunction display 477
Low beam see Low beam headlamps
Manual headlamp mode 144
Messages in the multifunction
display 477, 478, 479, 480, 481,
482
Replacing bulbs 504, 505
Switch 61, 143
Heated seats see Seat heating*
Heated steering wheel* 327
Height adjustment
Vehicle level control (Vehicles with Air
suspension program) 281
Vehicle level control (Vehicles with
enhanced Off-road Package*) 283High beam flasher 61, 147
High beam headlamps
Indicator lamp 29
Messages in the multifunction
display 478
Replacing bulbs 505, 507, 508
Switching on 61, 147
High mounted brake lamp 505
Hill start assist system 196
Hinged quarter windows* see
Power windows
Hood 378
Messages in the multifunction
display 474
Opening 378
Hooks
Loading 304
Horn 25
HVAC see Climate control or
automatic climate control (3-zone)*
Hydroplaning 352I
Identification labels see Labels
Ignition 42, 44, 57
Immobilizer 109
Indicator lamps see Lamps, Indicator and
warning
Infant and child restraint systems see
Children in the vehicle
Inflation pressure see Tires,
Inflation pressures
Information button see Tele Aid
Infrared reflecting windshield* 344
Inside door handle 120
Instrument cluster 26, 28, 152
Illumination brightness 153
Lamps 436
Messages in display see Multifunction
display messages
Multifunction display 155
Outside temperature indicator 153
Selecting language 172
Instrument lighting see Instrument cluster,
Illumination brightness
Instrument panel see Instrument cluster
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582 Index
Kickdown 196
Kilopascal 416
L
Labels 550
Certification 550
Emission control information 551
Engine number 551
Paintwork code 550
Vehicle Identification Number
(VIN) 550
Lamp sensor see Light sensor
Lamps, exterior 505
Front 505
Light sensor, Messages in the
multifunction display 477
Messages in display 477
Messages in the multifunction
display 477, 479, 481
Rear 505
Switch 143Lamps, indicator and warning
ABS 27, 436
Adaptive Damping System
(ADS)* 279
Alarm system 110
Battery (SmartKey with
KEYLESS-GO*) 119
Battery (SmartKey) 114
Brakes 27, 437, 438
Center console 31, 32, 447
CHECK ENGINE 29, 439, 440
Differential locks* 205
Distance warning lamp* 263
Downhill Speed Regulation 274
Engine diagnostics 29, 439, 440
ESP
®27, 441
Fog lamps, Front/rear 143
Front passenger front air bag off 31,
32, 80
Fuel reserve 29, 446
High beam headlamps 29
Instrument cluster 26, 28, 436, 437,
438, 439, 440, 441, 442, 443, 444,
446
Off-road driving program 278
Parktronic* 290Preglow indicator, Diesel engine 29
Seat belt telltale 29, 89, 442
Seat belts 443
Seat heating* 138
Seat ventilation* 140
SRS 29, 74, 89, 446
Turn signals 27
Vehicle level control 281, 283
Language, Setting 172
LATCH-type child seat anchors see
Children in the vehicle
Layout of poly-V-belt drive
(GL 320 CDI) 552
Layout of poly-V-belt drive
(GL 450, GL 550) 552
Leather upholstery*, Cleaning and care
of 434
Lever for cruise control 255
License plate lamps 514
Messages in the multifunction
display 479
Replacing bulbs 505, 514
Light alloy wheels, Cleaning 432
Light sensor
Messages in the multifunction
display 477
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588 Index
Seat belts 86
Children in the vehicle 91
Cleaning 433
Fastening 53
Height adjustment 55
Messages in the multifunction
display 443
Proper use of 55, 88
Safety guidelines 78
Telltale 29, 86, 442
Warning lamp 442, 443
Seat cushion depth see Seats
Seat heating* see Seats
Seat ventilation* see Seats
Seating capacity 389
Seats 45, 130
Adjusting 45
Cushion depth, Multicontour
seat* 138
Easy entry/exit feature for
third-row seats 130
Emergency exit for
third-row seats 132
Heating* 138
Lumbar support 137Memory function* 141
Multicontour seat* 138
Second-row, Folding 306
Third-row, Folding electrically 305,
308
Ventilation* 140
Securing cargo 302
Cargo tie-down rings 302
Hooks 304
Selector lever see Gear selector lever
Self-test
Lamps in the instrument cluster 436
OCS* 86
Tele Aid 332
Vehicle battery 528
Service and warranty information 10
Service intervals see Maintenance, Service
indicator
Service life
Tires 385
Service see Maintenance
Service system see Maintenance System
Service, Parts 548Settings
Adaptive Damping System
(ADS)* 278
Air suspension 278
Clock 174
Comfort functions* 181
Control system menus 158, 160
Control system submenus 159, 161,
171
Date 161, 171, 174
Daytime running lamp mode 175
Factory, SmartKey 114
Factory, SmartKey with
KEYLESS-GO* 118
Individual, Vehicle 168
Instrument cluster 172
Language, multifunction display 172,
173
Lighting 175
Memory function* 141
Resetting all, Control system 169
Selective, SmartKey 114
Selective, SmartKey with
KEYLESS-GO* 119
Time 174
Vehicle configuration 182
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