2008 MERCEDES-BENZ C300 4MATIC Owner's Manual

448 Practical hints
Battery
Starter battery
1Battery
2Positive terminal
3Negative terminal
4Ventilation hose
Disconnecting the battery
Apply the parking brake (page 134).
Make sure gear selector lever* is set to
positionP (manual transmission to
Neutral).
Turn off all electrical consumers.
Remove SmartKey from starter switch.Vehicles with KEYLESS-GO* (Canada
only):
Press the start / stop button until
the engine shuts off.
Open the driver’s door.
Open the hood (page 325).
Remove the filter box (page 447).
Read and observe safety instructions
and precautions (
page 446).
Disconnect the battery negative lead
from negative terminal3.
Remove cover from the positive
terminal2.
Disconnect the battery positive lead.iIf the battery is discharged, you must use
the mechanical key to unlock (
page 424) or
lock (
page 425) the vehicle.
Warning!G
With a disconnected battery

you will no longer be able to turn the
SmartKey in the starter switch and
pressing the KEYLESS-GO* start/stop
button (Canada only) will have no effect

vehicles with automatic transmission*:
the gear selector lever will remain
locked in positionP
!Always disconnect the starter battery in the
order described below. You could otherwise
damage the vehicle’s electronics.

449 Practical hints
Battery
Removing the battery
Remove the screw securing the
battery.
Remove the battery support and
bracket.
Pull out the battery ventilation hose4
from the battery (depending on battery
arrangement in your vehicle model, the
ventilation hose is located either on the
left or right side of the battery).
Take out the battery.
Charging and reinstalling the batteryCharge battery in accordance with the
instructions of the battery charger
manufacturer.
Reinstall the charged battery. Follow
the previously described steps in
reverse order.
iFor your convenience, have the starter bat-
tery removed by a Mercedes-Benz Center.
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 bat-
tery in its installed position. Contact an au-
thorized Mercedes-Benz Center for
information and availability. Charge battery
in accordance with the separate instruc-
tions for the accessory battery charger.
!Only use charging devices with a maximum
charging voltage of 14.8 V.
!The battery, its filler caps and the ventilation
hose
4 must always be securely installed when
the vehicle is in operation.

450 Practical hints
Battery
Reconnecting the battery
Turn off all electrical consumers.
Remove SmartKey from starter switch.
Vehicles with KEYLESS-GO* (Canada
only):
Open the driver’s door.
Connect the battery positive lead and
fasten its cover (
page 448).
Connect the battery negative lead
(
page 448).
Make sure that the ventilation hose4
is attached to the battery.
Reinstall filter box (page 447).
!Always connect the starter battery in the or-
der described below. Otherwise, the vehicle’s
electronics could be damaged.
!Never invert the terminal connections.
!Make sure the battery has a plug where the
ventilation hose
4 is attached to it.
iThe following procedures must be carried
out following any interruption of battery power
(e.g. due to reconnecting):

Reset the automatic exterior mirror fold in
function (
page 99).

Set the clock (page 170).
Vehicles with COMAND*: see COMAND op-
erator’s manual.

451 Practical hints
Jump starting
Jump starting
If the battery is discharged, the engine can
be started with jumper cables and the
battery of another vehicle. Observe the
following:

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

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

Only use a12-volt battery to jump start
your vehicle. Jump starting with a high-
er voltage battery could damage the ve-
hicle’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 an 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.
!Vehicles with automatic transmission*
and/or 4MATIC:
Do not tow-start the vehicle.
!Avoid repeated and lengthy starting
attempts.
Do not attempt to start the engine using a bat-
tery quick charge unit.
If engine does not run after several unsuccessful
starting attempts, have it checked at the nearest
authorized Mercedes-Benz Center.
Excessive unburned fuel generated by repeated
failed starting attempts may damage the catalyt-
ic converter and may present a fire risk.
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.
Warning!G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 446).

452 Practical hints
Jump starting
The battery is located in the engine com-
partment on the right hand side. For jump
starting, use the under hood terminals in
front of the battery.
Make sure the two vehicles do not
touch.
Turn off all electrical consumers,
except hazard warning flashers or work
lights.
Apply the parking brake (page 134).
Make sure gear selector lever* is set to
positionP (manual transmission to
Neutral).
Open the hood (page 326).
Slide red cover2 from positive under
hood terminal3 in direction of arrow. 1Positive terminal of charged battery
2Positive under hood terminal cover
3Positive under hood terminal in front of
discharged battery
4Negative under hood terminal
5Negative terminal of charged battery
Connect positive terminal1 of the
charged battery with positive under
hood terminal3 in front of the dis-
charged battery with the jumper cable.
Clamp cable to charged battery1
first.
Start the engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminal5 of the
charged battery to jumper cables and
attach other end to negative under
hood terminal4 on the vehicle. Clamp
cable to charged battery5 first
Start the engine of the disabled
vehicle.
You can now turn on the electrical con-
sumers. Do not switch on the headlamps
under any circumstances.
Remove the jumper cables first from
the negative terminals4 and5 and
then from the positive terminals3
and1.
You can now switch on the headlamps.
Slide red cover2 from positive under
hood terminal3 back.
Close the hood (page 326).
Have the battery checked at the near-
est authorized Mercedes-Benz Center.
!Never invert the terminal connections.

453 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.When circumstances do not permit the
recommended towing methods, the
vehicle may be towed with all wheels on
the ground or front wheels raised (except
vehicles with 4MATIC) only so far as neces-
sary to have the vehicle moved to a safe
location where the recommended towing
methods can be employed.
When towing the vehicle with all wheels on
the ground or the front axle raised (not per-
missible for vehicles with 4MATIC), the ve-
hicle may be towed only for distances up to
30 miles (50 km) and at a speed not to ex-
ceed 30 mph (50 km/h).
!Vehicles with automatic transmission*
and/or 4MATIC:
Do not tow-start the vehicle.
!Use flatbed or wheel lift/dolly equipment
with SmartKey or SmartKey with KEYLESS-GO*
(Canada only) 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.
Switch off the ESP
® (page 63) and the auto-
matic central locking (
page 173).
!Vehicles with 4MATIC:
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 SmartKey or
SmartKey with KEYLESS-GO* (Canada only)
is in starter switch position2.

454 Practical hints
Towing the vehicle
Warning!G
Without the engine running, there is no pow-
er assistance for the brake and steering sys-
tems. 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.
iWhen towing the vehicle with all wheels on
the ground, please note the following:
With the automatic central locking activated and
the SmartKey or SmartKey with KEYLESS-GO*
(Canada only) in starter switch position 2, the ve-
hicle doors lock if the left front wheel as well as
the right rear wheel are turning at vehicle speeds
of approximately 9 mph (15 km/h) or more.
To prevent the vehicle doors from locking,
deactivate the automatic central locking
(
page 173).
!If the vehicle is towed with the front axle
raised (not permissible for vehicles with
4MATIC), the gear selector lever must be in
positionN (manual transmission: gear shift lever
in neutral position) and the engine must be shut
off (SmartKey or SmartKey with KEYLESS-GO*
(Canada only) in starter switch position0 or1).
Active braking action through the ESP
® may
otherwise seriously damage the brake system.
While towing, the battery must be connected and
charged. Otherwise:

you will not be able to switch on the ignition

you will not be able to engage the automatic
transmission* in positionN (
page 127)
When towing the vehicle with all wheels on the
ground, the gear selector lever must be in
positionN (manual transmission: gear shift lever
in neutral position) and the SmartKey or
SmartKey with KEYLESS-GO* (Canada only)
must be in starter switch position2.
!Towing of the vehicle should only be done
using the properly installed towing eye bolt.
Never attach tow cable, tow rope or tow rod to
vehicle chassis, frame or suspension parts.
iTo signal turns while being towed with the
hazard warning flasher in use, turn SmartKey or
SmartKey with KEYLESS-GO* (Canada only) in
starter switch to position2 and activate the
combination switch for the left or right turn sig-
nal in the usual manner – only the selected turn
signal will operate.
Upon canceling the turn signal, the hazard
warning flasher will operate again.
!Make sure the parking brake is released.
iIf the battery is disconnected or discharged

the SmartKey or SmartKey with KEY-
LESS-GO* (Canada only) will not turn in the
starter switch

Vehicles with automatic transmission*: the
gear selector lever will remain locked in
positionP (
page 127).
For more information see “Battery”
(
page 446) and see “Jump starting”
(
page 451).

455 Practical hints
Towing the vehicle
Installing towing eye bolt
1Cover on right side of front bumper
1Cover on right side of rear bumperRemoving cover
Press mark on cover1 in the direction
of arrow.
Lift cover off to reveal the threaded
hole for towing eye bolt.
Installing towing eye bolt
Take towing eye bolt and wheel wrench
out of the vehicle tool kit in the trunk
(
page 420).
Screw towing eye bolt clockwise into
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 towing eye bolt and wheel
wrench in the vehicle tool kit in the
trunk.
Installing cover
Fit cover1 and snap into place.