421 Practical hints
What to do if …
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Possible cause/consequence
Possible solution
F
Change
key batteries
The SmartKey with KEYLESS-GO* batter-
ies are discharged.
Replace the batteries (
page 441).
Key
not recognized
The SmartKey with KEYLESS-GO* is not
recognized while the engine is running
because
the SmartKey with KEYLESS-GO* is
not in the vehicle
there is strong radio-frequency inter-
ference
Stop the vehicle as soon as it is safe
to do so.
Search for the SmartKey with
KEYLESS-GO*.
Otherwise the vehicle cannot be cen-
trally locked nor can the engine be
started again after the engine is
stopped.
Key
not recognized
The SmartKey with KEYLESS-GO* is mo-
mentarily not recognized.
Change the position of the SmartKey
in the vehicle.
Operate the vehicle with the
SmartKey in the starter switch if nec-
essary.
441 Practical hints
Replacing SmartKey batteries
Replacing SmartKey batteries
If the batteries in the SmartKey/SmartKey
with KEYLESS-GO* are discharged, the ve-
hicle can no longer be locked or unlocked.
It is recommended to have the batteries re-
placed at an authorized Mercedes-Benz
Center.Batteries contain materials that can harm
the environment if disposed of improperly.
Recycling of batteries is the preferred
method of disposal. Many states require
sellers of batteries to accept old batteries
for recycling.SmartKey/SmartKey with
KEYLESS-GO*
Replacement batteries: Lithium, type
CR 2025 or equivalent.
Remove the mechanical key1 out of
the SmartKey/SmartKey with
KEYLESS-GO* (
page 436).
1Mechanical key
2Battery compartment
Insert mechanical key1 into opening.
Press mechanical key1 in direction of
arrow.
The battery compartment is unlatched.
Warning!
G
Batteries contain poisonous and corrosive
substances. Therefore keep the batteries
out of reach of children.
If a battery is swallowed, seek medical help
immediately.
i
When inserting the batteries, make sure
they are clean and free of lint.
i
When replacing batteries, always replace
both batteries.
The required replacement batteries are available
at any Mercedes-Benz Center.
461 Practical hints
Battery
Disconnecting the battery
Apply the parking brake (
page 62).
Make sure the gear selector lever is set
to positionP.
Turn off all electrical consumers.
!
As with any other battery, disconnect the
battery if you do not intend to operate your vehi-
cle for an extended period of time to prevent bat-
tery discharge or connect an accessory battery
charge unit expressly approved by
Mercedes-Benz for your vehicle model to main-
tain the battery charge. Contact an authorized
Mercedes-Benz Center for further information.
The battery, the battery ventilation hose and the
lateral plug must always be securely installed
when the vehicle is in operation.
!
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 batteries only to avoid the
risk of acid burns in the event of an acci-
dent.
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
electronics can be damaged.
462 Practical hintsBattery
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 trunk.
Read and observe safety instructions
and precautions (
page 331) and
(
page 460).
Remove the luggage box (
page 433).
Disconnect the negative lead from neg-
ative terminal2 (
page 460).
Remove cover1 (
page 460) from
the positive terminal.
Disconnect the positive lead.
Removing the battery
Remove the screw-nuts securing the
battery.
Remove the battery bracket3
(page 460).
Pull out the battery ventilation hose4
(page 460) from the battery (de-
pending 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 batteryWarning!
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.
463 Practical hints
Battery
Charge battery in accordance with the
instructions of the battery charger
manufacturer.
Reinstall the charged battery. Follow
the previously described steps in re-
verse order.
Reconnecting the battery
Turn off all electrical consumers.
Connect the battery positive lead and
fasten its cover.
Connect the battery negative lead.
Install the luggage box (
page 433).
!
The battery and the battery ventilation hose
must always be securely installed when the vehi-
cle 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!
i
The following procedures must be carried
out following any interruption of battery power
(e.g. due to reconnection):
Set the clock (
page 171) (see COMAND
operator’s manual).
Synchronize the side windows
(page 239).
Synchronize the tilt/sliding sunroof
(page 244) or the tilt/sliding panel*
(page 248).
464 Practical hintsJump 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
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.
!
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
catalytic 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.
1Vehicles with gasoline engine only.
465 Practical hints
Jump starting
The battery is located in the trunk under-
neath the luggage box (
page 433). Only
jump start the vehicle from the battery in
the trunk.
Make sure the two vehicles do not
touch.
Turn off all electrical consumers.
Apply the parking brake (
page 62).
Make sure the gear selector lever is set
to positionP.
Open the trunk.1Positive terminal of discharged battery
2Negative terminal of discharged bat-
tery
3Positive terminal of charged battery
4Negative terminal of charged battery
Connect positive terminals1 and3
of the batteries with the jumper cable.
Clamp cable to charged battery3
first.
Start engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminals4 and2
of the batteries with the second jumper
cable. Clamp the cable to 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
negative terminals2 and4 and then
from positive terminals1 and3.
You can now switch on the headlamps.
Have the battery checked at the near-
est authorized Mercedes-Benz 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 331).
!
Never invert the terminal connections!
467 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.!
If the vehicle is towed with the front axle
raised (not permissible for vehicles with
4MATIC), the gear selector lever must be in
positionN and the engine must be shut off
(SmartKey in starter switch position0 or1).
Active braking action through the ESP
® may
otherwise seriously damage the brake system.
When towing the vehicle with all wheels on the
ground, the gear selector lever must be in
positionN and the SmartKey must be in starter
switch position2.
When towing the vehicle with all wheels on the
ground or the front axle raised, 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).
!
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
the vehicle chassis, frame or suspension parts.
i
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 approximately 9 mph (15 km/h) or
more.
To prevent the vehicle door locks from locking,
deactivate the automatic central locking
(
page 127).
i
To signal turns while being towed with the
hazard warning flasher in use, turn SmartKey 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 warn-
ing flasher will operate again.
i
The gear selector lever will remain locked in
positionP and the SmartKey will not turn in the
starter switch if the battery is disconnected or
discharged. For more information see “Batter-
ies” (page 460) or “Jump starting”
(
page 464).
For information on manual unlocking of the gear
selector lever, see (
page 438).