MERCEDES-BENZ R320 2008 W251 Owner's Manual

510 Practical hints
Battery
Connect the positive lead to the posi-
tive terminal and fasten it’s cover
(
page 509).
Connect the negative lead to the nega-
tive terminal (
page 509).
Charging the battery
If the battery is discharged, the battery can
be charged using the jump-start contacts
located in the engine compartment
(
page 512).
Charge the battery in accordance with
the instructions of the battery charger
manufacturer.
Batteries contain materials that can harm
the environment if disposed of improperly.
Large 12-volt storage batteries contain
lead. Recycling of batteries is the preferred
method of disposal. Many states require
sellers of batteries to accept old batteries
for recycling.
!Never invert the terminal connections!
iThe following procedures must be carried
out following any interruption of battery power
(e.g. due to disconnection):

Set the clock (page 176).
Vehicles with COMAND system with naviga-
tion module*: Time and date are set auto-
matically.

Synchronize the door windows
(
page 244).

Synchronize the power tilt/sliding sunroof*
(
page 250).

Synchronize the power tilt/sliding panel*
(
page 255).

Synchronize the power folding exterior rear
view mirrors* (
page 204).
Warning!G
Never charge a battery while still installed in
the vehicle unless the accessory battery
charge unit approved by Mercedes-Benz is
being used. Gases may escape during charg-
ing and cause explosions that may result in
paint damage, corrosion or personal injury.
An accessory battery charge unit specially
adapted for Mercedes-Benz vehicles and
tested and approved by Mercedes-Benz is
available, permitting the charging of the
battery in its installed position. Contact an
authorized Mercedes-Benz Light Truck
Center for information and availability.
Charge battery in accordance with the
separate instructions for the accessory
battery charger.


511 Practical hints
Jump starting
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 in the en-
gine compartment (
page 512).

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 more powerful 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 cata-
lytic 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.

512 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 the parking brake (page 65).
Set automatic transmission to
positionP (
page 192).
Open the hood (page 356).
Remove cover from negative
terminal1.
Flip up cover 3 of positive terminal 2
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 terminals2 and 4
with the jumper cable. Clamp cable to
charged battery 4 first.
Start engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminals1 and 5
of the batteries with the jumper cable.
Clamp cable to charged battery 5
first.
Start the engine of the disabled vehi-
cle.
You can now turn on the electrical con-
sumers. Do not switch on the headlamps
under any circumstances.
Remove the jumper cables first from
negative terminals1 and 5 and then
from positive terminals2 and 4.
You can now switch on the headlamps.
Have the battery checked at the
nearest 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.
!Never invert the terminal connections!

513 Practical hints
Towing the vehicle
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 104) and the
automatic central locking (
page 126).
!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 vehicles 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
as that will be necessary to adequately
control the vehicle.
Prior to towing the vehicle with all wheels on
the ground, make sure the automatic trans-
mission is in neutral positionN.

514 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 56).
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.

515 Practical hints
Towing the vehicle
Remove the KEYLESS-GO* start/stop
button from the starter switch
(
page 41).
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 56).
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.
Example illustration R 550 4MATIC
1Towing eye cover
!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.

516 Practical hints
Towing the vehicle
Example illustration R 550 4MATIC
1Towing eye coverRemoving 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 469).
Screw towing eye bolt in to its stop and
tighten with wheel wrench.Removing towing eye bolt
Loosen towing eye bolt counterclock-
wise with wheel wrench.
Unscrew towing eye bolt.
Store the towing eye bolt and wheel
wrench back into the vehicle tool kit
(
page 469).
Installing cover
Engage towing eye cover1 at top and
press at bottom.
Warning!G
In order to avoid possible serious burns or
injury, use extreme caution when removing
the cover, because the rear exhaust pipe is
extremely hot.

517 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, espe-
cially 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.

518 Practical hints
Fuses
The electrical fuses in your vehicle serve to
switch off malfunctioning power circuits.
If a fuse is blown, the components and
systems secured by that fuse will stop
operating.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 469).
The electrical fuses are located in different
fuse boxes:

on the passenger side of the engine
compartment (
page 519)

in the cargo compartment
(
page 519)

in the passenger compartment
(
page 520)Before replacing fuses:
Apply the parking brake (page 65).
Make sure automatic transmission is
set to position P (
page 192).
The gear position indicator in the
multifunction display should be on
P.
Turn off all electrical consumers.
Turn off the engine (page 66).
Remove the SmartKey from the starter
switch.
Vehicles with KEYLESS-GO*:
Open the driver’s door (this puts
the starter switch to position0,
same as with the SmartKey re-
moved from starter switch). The
driver’s door can then 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
approved 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
authorized 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.

519 Practical hints
Fuses
Fuse box in engine compartment
The main fuse box is located on the pas-
senger side of the engine compartment.
Open the hood (page 356).
1Clamp
2Main fuse box cover
Release clamp1.
Lift fuse box cover2 up.
Install fuse box cover in reverse order.
Close the hood after checking or re-
placing fuses (
page 358).
Fuse box in cargo compartment
The fuse box is located under the cargo
compartment cover on the right-hand side
of the spare wheel well.
Open the tailgate (page 119).
Lift the cargo compartment cover
(
page 467).
Secure cargo compartment cover with
securing hook (
page 468).
1Cover
Fold cover1 to the left as indicated by
the arrow.
!The fuse box cover must be installed
properly to prevent moisture and/or dirt from
entering the fuse box and possibly impairing fuse
operation.