426 Practical hints
Replacing SmartKey batteries
SmartKey / SmartKey with
KEYLESS-GO*
Replacement batteries: Lithium, type
CR 2025 or equivalent.
Remove the mechanical key from the
SmartKey or SmartKey with
KEYLESS-GO* (
page 410).
1Mechanical key
2Battery compartment
Insert mechanical key1 into the
opening.
Press mechanical key1 in direction of
arrow.
The battery compartment2 is un-
latched.
Pull battery compartment2 out of the
housing.
3Batteries
4Contact spring
Remove the batteries3.
Using a lint-free cloth, insert new
batteries3 under the contact
springs4 with the positive terminal
(+) side facing up.
Return battery compartment2 into
housing until it locks into place.
Slide mechanical key 1 back into the
SmartKey.
Check the operation of the SmartKey.
447 Practical hints
Battery
Battery
The battery is located in the engine
compartment on the right hand side.
1Clamps
Removing filter box:
Release clamps1.
Remove filter box.
Installing filter box:
Insert filter box properly.
Secure it with clamps1.
Warning!G
Failure to follow these instructions can re-
sult in severe injury or death.
Observe all safety instructions and
precautions when handling automotive
batteries (
page 321).
Never lean over batteries while connecting,
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 explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking etc.
!Never loosen or detach battery terminal
clamps while the engine is running or the
SmartKey is in the starter switch. Otherwise the
alternator and other electronic components
could be severely damaged.
Have the battery checked regularly by an autho-
rized Mercedes-Benz Center.
Refer to Maintenance Booklet for maintenance
intervals or contact an authorized
Mercedes-Benz Center for further information.
Warning!G
Do not place metal objects on the battery as
this could result in a short circuit.
Use leak-proof battery only to avoid the risk
of acid burns in the event of an accident.
448 Practical hints
Battery
2Negative terminal
3Positive terminal cover
Disconnecting the battery
Apply the parking brake (page 59).
Make sure gear selector lever is set to
positionP (
page 172).
Turn off all electrical consumers.
Remove SmartKey from starter switch.
Vehicles with KEYLESS-GO*:
Press the start / stop button until
the engine shuts off.
Open the driver’s door.
Open the hood (page 315).
Remove the filter box (page 447).
Read and observe safety instructions
and precautions (
page 447).
Disconnect the battery negative lead
from negative terminal2.
Remove cover3 from the positive ter-
minal.
Disconnect the battery positive lead.
Removing the battery
Remove the screw securing the
battery.
Remove the battery support and
bracket.
Pull out the ventilation hose from the
battery (depending on battery arrange-
ment in your vehicle model, the ventila-
tion hose is located either on the left or
right side of the battery).
Take out the battery.
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 on the gear selector lever will
have no effect
the gear selector lever will remain
locked in positionP
!Always disconnect the battery in the order
described below. Otherwise the vehicle’s elec-
tronics can be damaged.
449 Practical hints
Battery
Charging and reinstalling the battery
Charge battery in accordance with the
instructions of the battery charger
manufacturer.
Reinstall the charged battery. Follow
the previously described steps in
reverse order.
Reconnecting the battery
Turn off all electrical consumers.
Remove SmartKey from starter switch.
Vehicles with KEYLESS-GO*:
Open the driver’s door.
Connect the battery positive lead and
fasten its cover3 (
page 448).
Connect the battery negative lead2
(
page 448).
Reinstall the filter box (page 447).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.
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.
!The battery, its filler caps and the ventilation
hose must always be securely installed when the
vehicle is in operation.
!Always connect the battery in the order de-
scribed below. Otherwise the vehicle’s electron-
ics can be damaged.
!Never invert the terminal connections!
iThe following procedures must be carried
out following any interruption of battery power
(e.g. due to reconnecting):
Set the clock (page 158). Vehicles with
COMAND*: see COMAND operator’s manu-
al.
Synchronize the side windows
(
page 251).
450 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
when the engine and catalytic convert-
er 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 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.
!Do not tow-start the vehicle.
!Avoid repeated and lengthy starting at-
tempts.
Do not attempt to start the engine using a bat-
tery quick charge unit.
If the engine does not run after several unsuc-
cessful 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 321).
451 Practical hints
Jump starting
The battery is located on the right side of
the engine compartment. For jump start-
ing, use the terminals in front of the bat-
tery.
Make sure the two vehicles do not
touch.
Turn off all electrical consumers.
Apply the parking brake (page 59).
Make sure the gear selector lever is set
to positionP (
page 172).
Open the hood (page 315).
Flip up cover from positive under hood
terminal2 in front of the filter box
(
page 448).1Positive terminal of charged battery
2Positive under hood terminal in front of
discharged battery
3Negative under hood terminal in front
of discharged battery
4Negative terminal of charged battery
Connect the positive terminal1 of the
charged battery with the positive under
hood terminal 2 in front of the filter
box with the jumper cable. Clamp cable
to charged battery1 first.
Start engine of the vehicle with the
charged battery and run at idle speed.
Connect the negative terminal4 of
the charged battery with the negative
under hood terminal 3 in front of the
filter box with the second jumper cable.
Clamp the cable to the negative
terminal4 of the charged battery
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
the negative terminals3 and4 and
then from the positive terminals2
and1.
You can now switch on the headlamps.
Have the battery checked at the near-
est authorized Mercedes-Benz Center.
!Never invert the terminal connections.
453 Practical hints
Towing the vehicle
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 ve-
hicle. Adapt your driving accordingly.
iTo signal turns while being towed with the
hazard warning flasher in use, switch on the igni-
tion and activate the combination switch for the
left or right turn signal in the usual manner – only
the selected turn signal will operate.
Upon canceling the turn signal, the hazard warn-
ing flasher will operate again.
!When towing the vehicle with all wheels on
the ground, please note the following:
With the automatic central locking activated and
the SmartKey in starter switch position2, or
KEYLESS-GO* start/stop button in position2,
the vehicle doors lock if the left front wheel as
well as the right rear wheel are turning at vehicle
speeds of approx. 9 mph (15 km / h) or more.
To prevent the vehicle door locks from locking,
deactivate the automatic central locking
(
page 164).
Towing of the vehicle should only be done using
the properly installed towing eye bolt. Never at-
tach tow cable, tow rope or tow rod to the vehi-
cle chassis, frame or suspension parts.
iIf the battery is disconnected or discharged
the SmartKey will not turn in the starter
switch. For more information, see “Battery”
(
page 447) and “Jump starting”
(
page 450).
the gear selector lever will remain locked in
positionP. For information on manually un-
locking the transmission gear selector lever,
see (
page 412).
470 Technical data
Electrical system
ModelCLK 350CLK 550CLK 63 AMG
Generator (alternator)14 V/150 A14 V/180 A14 V/180 A
Starter motor14 V/1.4 KW14 V/1.7 KW14 V/2.2 KW
Battery12 V/100 Ah12 V/100 Ah12 V/100 Ah
Spark plugsBosch Platin Y 7 MPP 33
NGK PLKR 6ABosch F8 DPP 332
NGK PFR 5R-11NGK T 20036N
Electrode gap0.031 in (0.80 mm)0.039 in (1.00 mm)0.039 in (1.0 mm)
Tightening torque15 - 22 lb-ft (20 - 30 Nm)18.5 - 22 lb-ft (25 - 30 Nm)14.75 - 18.5 lb-ft (20 - 25 Nm)