2018 MERCEDES-BENZ C-CLASS CABRIOLET Owner's Manual

the household rubbish. They
must be collected separatelyand recycled to protect the
environment.
Dispose of batteries in an
environmentally friendly
manner. Take discharged
batteries to a qualified spe-
cialist workshop or a special
collection point for used bat-
teries.
The SmartKey batteries contain perchlorate
material, which may require special handling
and regard for the environment. National guide-
lines must be observed during disposal. In Cal-
ifornia, see www.dtsc.ca.gov/
HazardousWaste/Perchlorate/index.cfm .
Mercedes-Benz recommends that you have the
batteries replaced at a qualified specialist work-
shop.
Checking the battery
XPress the &or% button.
The battery is working properly if battery
check lamp :lights up briefly.
The battery is discharged if battery check
lamp :does not light up briefly.
XChange the battery (Ypage 79).
If the SmartKey battery is checked within the
signal reception range of the vehicle, pressing
the & or% button:
Rlocks or
Runlocks the vehicle
iYou can get a battery at any qualified spe-
cialist workshop.
Replacing the battery
You require a CR 2025 3 V cell battery.
XTake the mechanical key out of the SmartKey
(Ypage 78).
XPress mechanical key ;into the SmartKey
opening in the direction of the arrow until bat-
tery compartment cover :opens. Do not
hold battery compartment cover :closed
while doing so.
XRemove battery compartment cover :.
XRepeatedly tap the SmartKey against your
palm until battery=falls out.
XInsert the new battery with the positive ter-
minal facing upwards. Use a lint-free cloth to
do so.
XMake sure that the surface of the battery is
free of lint, grease and other contaminants.
XInsert the front tabs of battery compartment
cover :into the housing first and then press
to close it.
XInsert mechanical key ;into the SmartKey
(Ypage 78).
XCheck the function of all SmartKey buttons on
the vehicle.
SmartKey79
Opening and closing
Z

Problems with the SmartKey
ProblemPossible causes/consequences andMSolutions
You can no longer lock or
unlock the vehicle using
the SmartKey.The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 79) and replace it if necessary
(Ypage 79).
If this does not work:
XLock or unlock the vehicle using the mechanical key (Ypage 83).
There is interference from a powerful source of radio waves.
XLock or unlock the vehicle using the mechanical key (Ypage 83).
The SmartKey is faulty.
XLock or unlock the vehicle using the mechanical key (Ypage 83).
XHave the SmartKey checked at a qualified specialist workshop.
You can no longer lock or
unlock the vehicle using
KEYLESS-GO.KEYLESS-GO was deactivated.
XReactivate KEYLESS-GO (Ypage 77).
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 79) and replace it if necessary
(Ypage 79).
If this does not work:
XLock or unlock the vehicle using the mechanical key (Ypage 83).
There is interference from a powerful source of radio waves.
XLock or unlock the vehicle using the mechanical key (Ypage 83).
KEYLESS-GO is malfunctioning.
XLock/unlock the vehicle using the remote control function of the
SmartKey.
XHave the vehicle and SmartKey checked at a qualified specialist
workshop.
If the vehicle can also not be locked/unlocked using the remote con-
trol function:
XLock or unlock the vehicle using the mechanical key (Ypage 83).
XHave the vehicle and SmartKey checked at a qualified specialist
workshop.
The engine cannot be
started using the Smart-
Key.The on-board voltage is too low.
XSwitch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
XCheck the starter battery and charge it if necessary (Ypage 303).
or
XJump-start the vehicle (Ypage 304).
or
XConsult a qualified specialist workshop.
80SmartKey
Opening and closing

ProblemPossible causes/consequences andMSolutions
The engine cannot be
started using the Start/
Stop button. The Smart-
Key is in the vehicle.The vehicle is locked.
XUnlock the vehicle and try to start the vehicle again.
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 79) and replace it if necessary
(Ypage 79).
If this does not work:
XStart your vehicle with the SmartKey in the ignition lock.
There is interference from a powerful source of radio waves.
XStart your vehicle with the SmartKey in the ignition lock.
You have lost a Smart-
Key.XHave the SmartKey deactivated at a qualified specialist workshop.
XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
You have lost the
mechanical key.XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
Doors
Important safety notes
GWARNING
If children are left unsupervised in the vehicle,
they could:
Ropen the doors, thus endangering other
people or road users.
Rget out and disrupt traffic.
Roperate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
Rrelease the parking brake.
Rshifting the automatic transmission out of
park position P
RStart the engine.
There is a risk of an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children.
Unlocking and opening doors from
the inside
When a door is opened, the side window on that side opens slightly. When the door is closed, the
side window closes again.
!The side windows will not open/close if the
battery is discharged or if the side windows
have iced up. It will then not be possible to
close the door. Do not attempt to force the
door closed. You could otherwise damage the
door or the side window.
You can open a door from inside the vehicle
even if it has been locked. If the vehicle has been
locked with the SmartKey or with KEYLESS-GO,
opening a door from the inside will trigger the
anti-theft alarm system. Switch off the alarm
(
Ypage 74).
Doors81
Opening and closing
Z

XPull door handle;.
If the door is locked, locking knob :pops up.
The door is unlocked and opens.
Centrally locking and unlocking the
vehicle from the inside
You can centrally lock and unlock the vehicle
from the inside. The switches are on the driver’s
door.
XTo unlock: press button :.
XTo lock:press button ;.
When the front-passenger door is closed, the
vehicle is locked.
This does not lock or unlock the fuel filler flap or the glove box.
You cannot unlock the vehicle centrally from the
inside if the vehicle has been locked with the
SmartKey or KEYLESS-GO.
The doors can be opened from the inside.
If the vehicle has been locked with the SmartKey
or with KEYLESS-GO, opening a door from the
inside will trigger the anti-theft alarm system.
Switch off the alarm (
Ypage 74). If a locked door is opened from the inside, the
previous unlock status of the vehicle will be
taken into consideration if:
Rthe vehicle was locked using the locking but-
ton for the central locking, or
Rthe vehicle was locked automatically
The vehicle will be fully unlocked if it had previ-
ously been fully unlocked. If only the driver's
door had been previously unlocked, only the
door which has been opened from the inside is
unlocked.
Automatic locking feature
XTo deactivate: press and hold button :for
approximately five seconds until a tone
sounds.
XTo activate: press and hold button ;for
approximately five seconds until a tone
sounds.
If you press one of the two buttons and do not
hear a tone, the relevant setting has already
been selected.
The vehicle is locked automatically when the
ignition is switched on and the wheels are turn-
ing.
You could therefore be locked out if:
Rthe vehicle is being pushed
Rthe vehicle is being towed
Rthe vehicle is being tested on a dynamometer.
You can activate and deactivate the automatic
locking mechanism via the multimedia system
(see the Digital Operator's Manual).
82Doors
Opening and closing

Locking/unlocking the driver's door
with the mechanical key
i
If you want to centrally lock the vehicle using
the mechanical key, begin by pressing the
locking button for the interior locking mech-
anism while the driver's door is open. Then
lock the driver's door using the mechanical
key.
XInsert the mechanical key into opening :in
the protective cap.
XPull and hold the door handle.
XPull the protective cap on the mechanical key
as straight as possible away from the vehicle
until it releases.
XRelease the door handle.
XTo lock: turn the mechanical key clockwise as
far as it will go to position 1.
XTo unlock:turn the mechanical key counter-
clockwise as far as it will go to position 1.
If you use the mechanical key to unlock and
open the driver's door, the anti-theft alarm sys-
tem will be triggered. Switch off the alarm
(
Ypage 74).
Trunk
Important safety notes
GWARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Exhaust
gases can enter the vehicle interior if the
trunk lid is open when the engine is running,
especially if the vehicle is in motion. There is a
risk of poisoning.
Always switch off the engine before opening
the trunk lid. Never drive with the trunk lid
open.
GWARNING
If objects, luggage or loads are not secured or
not secured sufficiently, they could slip, tip
over or be flung around and thereby hit vehicle
occupants. There is a risk of injury, particu-
larly in the event of sudden braking or a sud-
den change in direction.
Always store objects so that they cannot be
flung around. Secure objects, luggage or
loads against slipping or tipping before the
journey.
!The trunk lid swings upwards when opened.
Therefore, make sure that there is sufficient
clearance above the trunk lid.
The opening dimensions of the trunk lid can be
found in the "Vehicle data" section
(
Ypage 345).
Do not leave the SmartKey in the trunk. You
could otherwise lock yourself out.
You should preferably place luggage or loads in
the trunk. Observe the loading guidelines
(
Ypage 263).
Opening and closing manually
Opening
XPress the Fbutton on the SmartKey.
The trunk lid opens.
Trunk83
Opening and closing
Z

Closing
XPull the trunk lid down using recess:and
push it closed.
XLock the vehicle if necessary with the &
button on the SmartKey or with KEYLESS-GO
(
Ypage 77).
Opening automatically from outside
Important safety notes
GWARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Exhaust
gases can enter the vehicle interior if the
trunk lid is open when the engine is running,
especially if the vehicle is in motion. There is a
risk of poisoning.
Always switch off the engine before opening
the trunk lid. Never drive with the trunk lid
open.
The opening dimensions of the trunk lid can be
found in the "Vehicle data" section
(
Ypage 345).
Opening automatically
You can open the trunk lid automatically using
the SmartKey.
XPress and hold the Fbutton on the Smart-
Key until the trunk lid opens.
Opening automatically from inside
Important safety notes
GWARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Exhaust
gases can enter the vehicle interior if the
trunk lid is open when the engine is running,
especially if the vehicle is in motion. There is a
risk of poisoning.
Always switch off the engine before opening
the trunk lid. Never drive with the trunk lid
open.
!The trunk lid swings upwards when opened.
Therefore, make sure that there is sufficient
clearance above the trunk lid.
The opening dimensions of the trunk lid can be
found in the "Vehicle data" section
(
Ypage 345).
Opening
You can open the trunk lid from the driver's seat
when the vehicle is stationary and unlocked.
XPull remote operating switch :for the trunk
lid until the trunk lid opens.
Locking the trunk separately
You can lock the trunk separately. If you then
unlock the vehicle centrally, the trunk remains
locked and cannot be opened.
84Trunk
Opening and closing

XTo activate:close the trunk lid.
XOpen the glove box.
XSlide the switch to position 1.
If the vehicle is unlocked centrally, the trunk
remains locked.
iYou can also lock the glove box
(Ypage 264).
XTo deactivate: open the glove box.
XSlide the switch to position 2.
If the vehicle is unlocked centrally, the trunk
will also be unlocked.
Emergency release for the trunk
You can unlock the trunk lid from the inside with
the emergency release button.
XPress emergency release button :briefly.
The trunk lid unlocks and opens.
The trunk lid can be unlocked with the trunk lid
emergency release when the vehicle is station-
ary or while driving.
The trunk lid emergency release does not unlock
the trunk lid if the battery is disconnected or
discharged. Trunk lid emergency release light:
Remergency release button
:flashes for
30 minutes after the trunk lid is opened
Remergency release button :flashes for
60 minutes after the trunk lid is closed
Side windows
Important safety notes
GWARNING
While opening the side windows, body parts
could become trapped between the side win-
dow and the door frame as the side window
moves. There is a risk of injury.
Make sure that nobody touches the side win-
dow during the opening procedure. If some-
body becomes trapped, release the switch or
pull the switch to close the side window again.
GWARNING
While closing the side windows, body parts in
the closing area could become trapped. There is a risk of injury.
When closing make sure that no parts of the
body are in the closing area. If somebody
becomes trapped, release the switch or press
the switch to open the side window again.
Side window reversing feature
The side windows are equipped with an auto-
matic reversing feature. If a solid object blocks
or restricts a side window from traveling
upwards during the automatic closing process,
the side window opens again automatically. Dur-
ing the manual closing process, the side window
only opens again automatically after the corre-
sponding switch is released. The automatic
reversing feature is only an aid and is no substi- tute for your attention when closing a side win-
dow.
Side windows85
Opening and closing
Z

GWARNING
The reversing feature does not react:
Rto soft, light and thin objects, e.g. small fin-
gers
Rwhile resetting
This means that the reversing feature cannot
prevent someone being trapped in these sit-
uations. There is a risk of injury.
Make sure that no body parts are in close
proximity during the closing procedure. If
someone becomes trapped, press the switch
to open the side window again.
Opening and closing the side win-
dows
The switches for the side windows are located
on the driver's door. There is also a switch for
the front-passenger side window on the front-
passenger door.
The switches on the driver's door take prece-
dence.
:Front left
;Front right
=Rear right
?Rear left
XTurn the SmartKey to position 1or2 in the
ignition lock.
XTo open manually: press and hold the cor-
responding switch.
XTo open fully: press the switch beyond the
pressure point and release it.
Automatic operation is started.
XTo close manually: pull the corresponding
switch and hold it.
XTo close fully: pull the switch beyond the
pressure point and release it.
Automatic operation is started.
XTo interrupt automatic operation: press/
pull the corresponding switch again.
If you press the switch beyond the pressure
point and release, automatic operation is star-
ted in the corresponding direction. You can stop
automatic operation by pressing/pulling the
switch again.
You can continue to operate the side windows
after you switch off the engine or remove the
SmartKey. This function is available for up to five
minutes or until the driver's or front-passenger
door is opened.
Opening and closing all side windows
Using the switch on the center console
GWARNING
While closing the side windows, body parts in
the closing area could become trapped. There is a risk of injury.
When closing make sure that no parts of the
body are in the closing area. If somebody
becomes trapped, release the switch or press
the switch to open the side window again.
You can use button :to open or close all side
windows simultaneously.
XTurn the SmartKey to position 1or2 in the
ignition lock.
XTo open all side windows: press and hold
button :to the point of resistance.
86Side windows
Opening and closing