2008 MERCEDES-BENZ GL550 Owner's Manual

536 Practical hints
Jump starting
If the battery is discharged, the engine can
be started with jumper cables and the bat-
tery of another vehicle. Observe the follow-
ing:

Jump starting should only be performed
using the jump-start contacts located
in the engine compartment
(
page 537).

Jump starting should only be performed
when the engine and catalytic
converter
1 are cold.

Do not start the engine if the battery is
frozen. Let the battery thaw out first.

Only jump start from batteries with the
same voltage rating (12 V). Jump start-
ing with a higher voltage battery could
damage the vehicle’s electrical system,
which will not be covered by the
Mercedes-Benz Limited Warranty.

Only use jumper cables with sufficient
cross-section and insulated terminal
clamps.

Always make sure the jumper cables
are not on or near pulleys, fans or other
parts that move when the engine is
started or running.
Warning!G
Failure to follow these directions will cause
damage to the electronic components, and
can lead to a battery explosion and severe
injury or death.
Never lean over batteries while connecting
or jump starting, you might get injured.
Battery fluid contains sulfuric acid. Do not
allow this fluid to come in contact with eyes,
skin or clothing. In case it does, immediately
flush affected area with water, and seek
medical help if necessary.
A battery will also produce hydrogen gas,
which is flammable and very explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking, etc.
Attempting to jump start a frozen battery
can result in it exploding, causing personal
injury.
Read all instructions before proceeding.
1Vehicles with gasoline engine only.
!Do not tow-start the vehicle.
!Avoid repeated and lengthy starting
attempts.
Do not attempt to start the engine using a
battery quick charge unit.
If the engine does not run after several unsuc-
cessful starting attempts, have it checked at the
nearest authorized Mercedes-Benz Light Truck
Center.
Excessive unburned fuel generated by repeated
failed starting attempts may damage the catalyt-
ic converter
1.
Make sure the jumper cables do not have loose
or missing insulation.
Make sure the cable clamps do not touch any
other metal part while the other end is still at-
tached to a battery.
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537 Practical hints
Jump starting
The jump-start contacts are located in the
engine compartment.
1Negative (-) terminal
2Positive (+) terminal
3Positive terminal cover
Make sure the two vehicles do not
touch.
Turn off all electrical consumers.
Apply parking brake (page 67).
Set automatic transmission to
positionP (
page 191).
Open the hood (page 378).
Remove cover from negative
terminal1.
Flip up cover3 of positive terminal2
in direction of arrow.
1Negative terminal of discharged
battery
2Positive terminal of discharged battery
4Positive terminal of charged battery
5Negative terminal of charged battery
Connect positive terminal2 and4
with the jumper cable. Clamp cable to
charged battery4 first.
Start engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminals1 and5
of the batteries with the second jumper
cable. Clamp the cable to negative
terminal5 of the charged battery
first.
Start the engine of the disabled vehi-
cle.
You can now turn on the electrical consum-
ers. Do not switch on the headlamps under
any circumstances.
Remove the jumper cables first from
negative terminals1 and5 and then
from positive terminals2 and4.
You can now switch on the headlamps.
Have the battery checked at the near-
est authorized Mercedes-Benz Light
Truck Center.
Warning!G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 528).
!Never invert the terminal connections!
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538 Practical hints
Towing the vehicle
Mercedes-Benz recommends that the
vehicle be transported with all wheels off
the ground using flatbed or appropriate
wheel lift/dolly equipment. This method is
preferable to other types of towing.If circumstances do not permit the recom-
mended towing methods, the vehicle may
be towed with all wheels on the ground
only so far as necessary to have the vehicle
moved to a safe location where the recom-
mended towing methods can be employed.
When towing the vehicle with all wheels on
the ground, the vehicle may be towed only
for distances up to 30 miles (50 km) and at
a speed not to exceed 30 mph (50 km/h).
!Do not tow-start the vehicle.
!Use flatbed or wheel lift/dolly equipment,
with the SmartKey in starter switch turned to
position0.
Do not tow with sling-type equipment. Towing
with sling-type equipment over bumpy roads will
damage radiator and supports.
To prevent damage during transport, do not tie
down vehicle by its chassis or suspension parts.
Use the towing eyes.
Switch off the ESP
® (page 105) and the
automatic central locking (
page 128).
!Do not tow with one axle raised. Doing so
could damage the transfer case, which is not
covered by the Mercedes-Benz Limited
Warranty.
All wheels must be on or off the ground. Observe
instructions for towing the vehicle with all
wheels on the ground.
Warning!G
If circumstances require towing the vehicle
with all wheels on the ground, always tow
with a tow bar if

the engine will not run

there is a malfunction in the brake
system

there is a malfunction in the power
supply or in the vehicle’s electrical
system
This is necessary to adequately control the
towed vehicle.
Prior to towing the vehicle with all wheels on
the ground, make sure the automatic trans-
mission is in neutral positionN.
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539 Practical hints
Towing the vehicle
If you want the gear position to remain in
neutral positionN, observe the following
instructions.Vehicles with SmartKey:
With the vehicle at a standstill and the
ignition switched on shift the automatic
transmission to neutral positionN.
If engaged, release the parking brake
(
page 59).
Switch off the ignition and leave the
SmartKey in the starter switch.
Vehicles with KEYLESS-GO*:
With the vehicle at a standstill, depress
the brake pedal and keep it pressed.
With the ignition switched on shift the
automatic transmission to park
positionP.
Release the brake pedal.
Warning!G
With the engine not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to brake and steer the
vehicle. Adapt your driving accordingly.
!When towing the vehicle with all wheels on
the ground, the automatic transmission must be
in neutral positionN.
If you turn off the engine

using the SmartKey and

remove the SmartKey from the starter
switch
or

open a front door

or when using the KEYLESS-GO* start/stop
button and open a front door
the automatic transmission will shift to park
positionP automatically.
Warning!G
When leaving the SmartKey or SmartKey
with KEYLESS-GO* in the starter switch, do
not leave children unattended in the vehicle.
It is possible for children to switch on the
ignition which could result in unsupervised
use of vehicle equipment.
A child’s unsupervised access to a vehicle
could result in an accident and/or serious
personal injury.

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540 Practical hints
Towing the vehicle
Remove the KEYLESS-GO* start/stop
button from the starter switch
(
page 43).
Insert the SmartKey with
KEYLESS-GO* into the starter switch.
Switch on the ignition.
Depress the brake pedal.
Shift the automatic transmission to
neutral positionN.
Release the brake pedal.
If engaged, release the parking brake
(
page 59).
Switch off the ignition and leave the
SmartKey with KEYLESS-GO* in the
starter switch.
Installing towing eye bolt
Depending on whether you are towing a
vehicle or you are being towed, the towing
eye bolt can be screwed into threaded
holes which are located behind covers on
the right-hand side of each bumper.
1Cover!Towing of the vehicle should only be done
using the properly installed towing eye bolt.
Never attach a tow cable, tow rope or tow rod to
the vehicle chassis, frame or suspension parts.
iTo signal turns while being towed with
hazard warning flasher in use, set the starter
switch to position2 and activate combination
switch for left or right turn signal in usual manner
– only the selected turn signal will operate.
Upon canceling the turn signal, the hazard warn-
ing flasher will operate again.

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541 Practical hints
Towing the vehicle
1Cover
Example illustration front bumper
2Towing eye bolt
Removing cover
Press mark on cover1 as indicated by
the arrow.
Lift off cover1 to reveal the threaded
hole for towing eye bolt.Installing towing eye bolt
Take the towing eye bolt and wheel
wrench from the vehicle tool kit
(
page 490).
Screw towing eye bolt2 in clockwise
to its stop and tighten with wheel
wrench.
Removing towing eye bolt
Loosen towing eye bolt2 counter-
clockwise with wheel wrench.
Unscrew towing eye bolt2.
Store the towing eye bolt and wheel
wrench back into the vehicle tool kit
(
page 490).
Installing cover
Engage cover1 at top and press at
bottom.
Warning!G
In order to avoid possible serious burns or
injury, use extreme caution when removing
the rear cover, because the rear exhaust
pipe is extremely hot.
iCover1 is secured to the bumper by a
plastic cord.
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542 Practical hints
Towing the vehicle
Stranded vehicle
Freeing a stranded vehicle, on which the
wheels are dug into sand or mud, should
be done with the greatest of care, especial-
ly if the vehicle is heavily loaded.
Avoid pulling the vehicle abruptly or diago-
nally, since it could result in damage to the
chassis alignment.
Never try to free a vehicle that is still cou-
pled to a trailer.
If possible, a vehicle equipped with trailer
hitch receiver should be pulled backward
in its own previously made tracks.
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543 Practical hints
Fuses
Fuses
The electrical fuses in your vehicle serve to
switch off malfunctioning power circuits.
If a fuse is blown, the components and sys-
tems secured by that fuse will stop operat-
ing.If a newly inserted fuse blows again, have
the cause determined and rectified by an
authorized Mercedes-Benz Light Truck
Center.
A fuse chart explains the fuse allocation
and fuse amperages. It is located in the
cargo compartment with the vehicle tool
kit (
page 490).
The electrical fuses are located in different
fuse boxes:

Fuse box in engine compartment
(
page 544)

Fuse box in cargo compartment
(
page 544)

Fuse box in passenger compartment
(
page 545)Before replacing fuses:
Apply parking brake (page 67).
Make sure the automatic transmission
is set toP (
page 191).
The gear position indicator in the multi-
function display should be on
P.
Turn off all electrical consumers.
Turn off the engine (page 41).
Remove the SmartKey from the starter
switch.
Vehicles with KEYLESS-GO*:
Open the driver’s door (this puts
the starter switch in position0,
same as with the SmartKey re-
moved from the starter switch). The
driver’s door then can be closed
again.
Warning!G
Only use fuses approved by Mercedes-Benz
with the specified amperage for the system
in question and do not attempt to repair or
bridge a blown fuse. Using other than ap-
proved fuses or using repaired or bridged
fuses may cause an overload leading to a
fire, and/or cause damage to electrical
components and/or systems. Have the
cause determined and remedied by an au-
thorized Mercedes-Benz Light Truck Center.
iA blown fuse must be replaced by an appro-
priate spare fuse (recognizable by its color or the
fuse rating given on the fuse) of the amperage
recommended in the fuse chart. Any
Mercedes-Benz Light Truck Center will be glad to
advise you on this subject.
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