Page 84 of 400

84 Controls in detailLocking and unlocking
Checking the batteries
Press button‹ orŒ.
Battery check lamp5 comes on
briefly to indicate that the SmartKey
batteries are in order.Unlocking and opening the trunk lid
You can unlock and open the trunk
separately.
A minimum height clearance of 5.71 ft
(1.74 m) is required to open the trunk lid.
Press buttonŠ until trunk unlocks
and begins to open.
The trunk can also be opened from its
inside in an emergency, see “Trunk lid
emergency release” (
page 88).
!If you can no longer lock or unlock the
vehicle with the SmartKey, then either
the batteries in the SmartKey are dis-
charged, the SmartKey is malfunction-
ing or the vehicle battery is drained.
Check the batteries in the
SmartKey (
page 84) and replace
them if necessary (
page 307).
or
Use the mechanical key to unlock
the doors (
page 305) and the
trunk lid (
page 306) as required.
or
Use the mechanical key to lock the
doors (
page 306) and the trunk
lid (
page 306) as required.
or
Have the vehicle battery and the
battery connections checked.
If the SmartKey is malfunctioning,
contact an authorized Mercedes-Benz
Center.!If battery check lamp5 does not
come on briefly during check, then the
SmartKey batteries are discharged.
Replace the batteries (
page 307).
You can obtain the required batteries
at any authorized Mercedes-Benz
Center.
iIf the batteries are checked within
signal range of the vehicle, pressing
the‹ orŒ button will lock or
unlock the vehicle accordingly. !The trunk lid swings open upwards
automatically. Always make sure there
is sufficient overhead clearance.
Page 263 of 400

263 Operation
Winter driving
Winter driving
Before the onset of winter, have your
vehicle winterized at an authorized
Mercedes-Benz Center. This service
includes:
Check of anticorrosion and antifreeze
concentration.
Addition of cleaning concentrate to the
water of the windshield and headlamp
cleaning system. Add MB Concentrate
“S” to a premixed windshield washer
solvent/antifreeze which is formulated
for below freezing temperatures
(page 358).
Battery test. Battery capacity drops
with decreasing ambient temperature.
A well charged battery helps to ensure
that the engine can be started, even at
low ambient temperatures.
Tire change. Mercedes-Benz recom-
mends M+S rated radial-ply tires with a
minimum tread depth of approximately 1/6in (4 mm) on all four wheels for the
winter season.
Winter tires
Always use winter tires at temperatures
below 45°F (7°C) and whenever wintry
road conditions prevail. Use of winter tires
is the only way to achieve the maximum
effectiveness of the ABS, ESP and 4MATIC
in winter operation.
For safe handling, ensure that all mounted
winter tires are of the same make and have
the same tread design.Always observe the speed rating of the
winter tires installed on your vehicle. If the
maximum speed for which your tires are
rated is below the speed rating of your
vehicle, you must place a notice to this
effect where it will be seen by the driver.
Such notices are available from your tire
dealer or from any authorized
Mercedes-Benz Center.Warning!
G
Winter tires with a tread depth under
1/6in
(4 mm) must be replaced. They are no
longer suitable for winter operation.
Warning!
G
If you use your spare tire when winter tires
are fitted on the other wheels, be aware that
the difference in tire characteristics may
very well impair turning stability and that
overall driving stability may be reduced.
Adapt your driving style accordingly.
Have the spare tire replaced with a winter
tire at the nearest authorized
Mercedes-Benz Center.
Page 274 of 400

274 Practical hintsWhat to do if …
What to do if …Lamps in instrument clusterGeneral information:
If a bulb in the instrument cluster fails to
come on during the bulb self-check when turning the SmartKey in the starter switch
to position2, have it checked and replaced
if necessary.Problem
Possible cause
Suggested solution
-
The yellow ABS malfunction
indicator lamp comes on while
driving.
The ABS has detected a malfunction and has
switched off. The BAS and the ESP are also
switched off (see messages in display).
The brake system is still functioning normally
but without the ABS available.
Continue driving with added caution.
Wheels may lock during hard braking,
reducing steering capability.
Have the system checked at an autho-
rized Mercedes-Benz Center as soon
as possible.
Failure to follow these instructions
increases the risk of an accident.
Read and observe messages in the
display (
page 280).
The charging voltage has fallen below ten
volts. The ABS has switched off.
When the voltage is above this value
again, the ABS is operational again.
If necessary, have the generator
(alternator) and battery checked.
Page 307 of 400

307 Practical hints
Unlocking/locking in an emergency
Changing batteries in the SmartKey
If the batteries in the SmartKey are
discharged, the vehicle can no longer be
locked or unlocked. It is recommended to
have the batteries replaced 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.1Mechanical key
2Battery compartment
Replacement batteries: Lithium, type
CR 2025 or equivalent.
Remove mechanical key1
(page 305).
Insert mechanical key1 in side
opening and push grey slide.
Battery compartment2 is unlatched.
Pull battery compartment2 out of the
SmartKey housing in direction of
arrow.
3Battery
4Contact spring
Remove the batteries.
Using a lint-free cloth, insert new
batteries under contact spring with the
plus (+) side facing up.
Return battery compartment2 into
housing until it locks into place.
Warning!
G
Keep the batteries out of reach of children.
If a battery is swallowed, seek medical help
immediately.
iWhen changing batteries, always
replace both batteries.
The required replacement batteries are
available at any Mercedes-Benz
Center.