2008 MERCEDES-BENZ GL550 tow

499 Practical hints
Resetting activated head restraints
Resetting activated head restraints
If the active head restraints have been trig-
gered in a rear-end collision, the active
head restraints must be reset. Otherwise,
the active head restraints cannot offer any
additional protection in the event of anoth-
er rear-end collision.
You can tell that the head restraints have
been activated when they have been
moved forward and cannot be adjusted.
Vehicles without Rear seat entertain-
ment system*1Pull
2Adjust downward
3Press
Pull the top of the head restraint cush-
ion in direction of arrow1 as far as it
will go.
Adjust the head restraint cushion
downward in direction of arrow2 as
far as it will go.
Firmly press the top of the active head
restraint cushion towards the head
restraint cover in direction of arrow3
until it engages.
Warning!G
For safety reasons, have the active head re-
straints checked by an authorized
Mercedes-Benz Light Truck Center after a
rear-end collision.
Warning!G
When pushing back the head restraint cush-
ion, take care that your fingers do not be-
come caught between the head restraint
cushion and the cover. Failing to do so may
lead to injury.
!Be careful not to damage upholstery.
iFor your convenience, we recommend that
you have this work carried out by an authorized
Mercedes-Benz Light Truck Center.
iPressing the head restraint cushion back
requires high force. If you encounter difficulties
when pushing the head restraint back please
have the procedure performed at an authorized
Mercedes-Benz Light Truck Center.

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501 Practical hints
Resetting activated head restraints
Firmly press the active head restraint
cushion backward towards the head
restraint cover in direction of arrow
until it engages.
Repeat this procedure on the active
head restraint for the second front
seat.
After resetting the active head
restraints store reset tool1 in the
Mercedes-Benz vehicle literature
pouch.
For information on active head restraints,
see “Active head restraint” (
page 90).
For information on head restraint adjust-
ment, see “Seats” (
page 45).
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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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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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