2012 MERCEDES-BENZ B-CLASS door lock

Problem Possible causes/consequences and
M SolutionsThe engine cannot be
started using the
SmartKey. The on-board voltage is too low.
X
Switch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
X Check the starter battery and charge it if necessary
(Y page 285).
or
X Jump-start the vehicle (Y page 289).
or
X Consult a qualified specialist workshop. The engine cannot be
started using the
SmartKey. The steering lock is mechanically blocked.
X
Remove the SmartKey and reinsert it into the ignition lock. While
doing this, turn the steering wheel in both directions. Doors
Important safety notes
G
WARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shift the automatic transmission out of
parking position P.
R starting 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. G
WARNING
If persons, particularly children are subjected
to prolonged exposure to extreme heat or
cold, there is a risk of injury, possibly even
fatal. Never leave children unattended in the
vehicle. Unlocking and opening doors from
the inside
X
To unlock a front door: pull door
handle ;.
Locking knob : pops up.
The door is unlocked and can be opened. Doors
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X
To open a front door: pull door
handle ;.
X To unlock a rear door: pull up locking
knob :.
The door is unlocked and can be opened.
X To open a rear door: pull door handle ;.
You can open a door from inside the vehicle
even if it has been locked. You can open the
rear doors from
inside the vehicle unless they
are secured by the child-proof lock
(Y page 58).
If the vehicle has previously been locked with
the SmartKey, opening a door from the inside
will trigger the anti-theft alarm system.
Switch off the alarm (Y page 65). Centrally locking and unlocking the
vehicle from the inside
You can centrally lock or unlock the vehicle
from the inside.

This can be useful if you wish
to lock the vehicle before pulling away, for
example. X
To unlock: press button :.
X To lock: press button ;.
The vehicle locks when all the doors and
the tailgate are closed.
Meanwhile, the fuel filler flap will not be
locked or unlocked.
You cannot unlock the vehicle centrally from
the inside if

the vehicle has been locked with
the SmartKey. You can open a door from inside the vehicle
even if it has been locked. You can open the
rear doors
from

inside the vehicle unless they
are secured by the child-proof lock
(Y page 58).
If the vehicle has previously been locked with
the SmartKey, opening a door from the inside
will trigger the anti-theft alarm system.
Switch off the alarm (Y page 65).
If the vehicle has been locked using the
locking button for the central locking, or has
been locked automatically, and a door is
opened from the inside:
R the vehicle will be fully unlocked if it had
previously been fully unlocked
R only the door which has been opened form
the inside is unlocked if only the driver's
door had been previously unlocked Automatic locking feature
X
To deactivate: press and hold button :
for about five

seconds until a tone sounds.
X To activate: press and hold button ; for
about five seconds until a tone sounds.
i 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
turning. 74
Doors
Opening and closing
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You could therefore lock yourself out if:
R
the vehicle is being pushed.
R the vehicle is being towed.
R the vehicle is on a roller dynamometer.
You can also switch the automatic locking
function on and off using the on-board
computer (Y page 198). Unlocking the driver's door
(mechanical key)
If the vehicle
can no longer be unlocked with
the SmartKey, use the mechanical key.
If you use the mechanical key to unlock and
open the driver's door, the anti-theft alarm
system will be triggered ( Y page 65).
X Take the mechanical key out of the
SmartKey (Y page 69).
X Insert the mechanical key into the lock of
the driver's door as far as it will go. X
Turn the mechanical key counter-clockwise
to position 1.
The door is unlocked.
X Turn the mechanical key back and remove
it.
X Insert the mechanical key into the
SmartKey. Locking the vehicle (mechanical key)
If the vehicle

can no longer be locked with the
SmartKey, use the mechanical key. X
Open the driver's door.
X Close the front-passenger door, the rear
doors and the tailgate.
X Press the locking button (Y page 74).
X Check whether the locking knobs on the
front-passenger door and the rear doors
are still visible. Press down the locking
knobs manually, if necessary (Y page 73).
X Close the driver's door.
X Take the mechanical key out of the
SmartKey (

Y page 69).
X Insert the mechanical key into the lock of
the driver's door as far as it will go. X
Turn the mechanical key clockwise as far
as it will go to position 1.
X Turn the mechanical key back and remove
it.
X Make sure that the doors and the tailgate
are locked.
X Insert the mechanical key into the
SmartKey.
i If you lock

the vehicle as described above,
the fuel filler flap is not locked. The anti-
theft alarm system is not armed. Cargo compartment
Important safety notes
G
WARNING
Combustion engines emit poisonous exhaust
gases such as

carbon monoxide. If the tailgate
is open when the engine is running, Cargo compartment
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You can reach the emergency release via the
cargo compartment. Fold the rear backrests
forward (
Y page 240).
X Take the mechanical key out of the
SmartKey (Y page 69). X
Insert mechanical key ; into the opening
in paneling :.
X Turn mechanical key ; 90° clockwise.
X Push mechanical key ; in the
direction of
the arrow and open the tailgate. Side windows
Important safety notes
G
WARNING
While opening the side windows, body parts
in the closing area could become trapped.
There is a risk of injury.
Make sure that no body parts are in close
proximity during the closing procedure. If
somebody becomes trapped, release the
switch or press the switch to open the side
window again. G
WARNING
If children operate the side windows they
could become trapped,

particularly if they are
left unsupervised. There is a risk of injury.
Activate the override feature for the rear side
windows. When leaving the vehicle, always
take the SmartKey with you and lock the
vehicle. Never leave children unsupervised in
the vehicle. Side window reversing feature
The side windows are equipped with an
automatic reversing feature. If a solid object
blocks or restricts a side window during the
closing process, the

side window opens again
automatically. However, the automatic
reversing feature is only an aid and does not
relieve you of the responsibility of paying
attention when closing a side window. G
WARNING
The reversing feature does not react:
R to soft, light and thin objects, e.g. small
fingers
R over the last

4 mm of the closing movement
R during resetting
R when closing the side window again
manually immediately after automatic
reversing
This means that the reversing feature cannot
prevent someone being trapped in these
situations. 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
windows
The switches for

all side windows are located
on the driver's door. There is also a switch on
each door for the corresponding side window.
The switches on the driver's door take
precedence. Side windows
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:
Front left
; Front right
= Rear right
? Rear left
i When the override feature for the side
windows is activated (
Y page 58), the side
windows
cannot be operated from the rear.
X Turn the SmartKey to position 1 or 2
in the
ignition lock.
X To open: press the corresponding switch.
X To open fully: press the corresponding
switch beyond the point of resistance.
Automatic closing is started.
X To close: pull the corresponding switch.
X To close fully: pull the corresponding
switch beyond the pressure point.
Automatic closing is started.
X To interrupt the automatic opening/
closing: press/pull the corresponding
switch again.
i If you press the switch beyond the point
of resistance, an automatic opening/
closing process is started in the
corresponding direction. You can stop
automatic operation by operating the
switch again.
i 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. Convenience opening
You can ventilate

the vehicle before you start
driving. To do this, the SmartKey is used to
carry out the following functions
simultaneously:
R unlock the vehicle
R open the side windows
R open the panorama roof with power tilt/
sliding panel and the roller sunblinds
i The convenience opening feature can
only be operated using the SmartKey. The
SmartKey must be close to the driver's
door handle.
X Point the tip of the SmartKey at the driver's
door handle.
X Press and hold the % button until the
side windows and the panorama roof with
power tilt/sliding panel are in the desired
position.
If the roller

sunblinds of the panorama roof
with power tilt/sliding panel are closed, the
roller sunblinds are opened first.
X Press and hold the % button again
until
the panorama roof with power tilt/sliding
panel is in the desired position.
X To interrupt convenience opening:
release the % button. Convenience closing feature
G
WARNING
When the convenience closing feature is
operating, parts of the body could become
trapped in the

closing area of the side window
and the sliding sunroof. There is a risk of
injury.
Observe the complete closing procedure
when the convenience closing feature is
operating. Make sure that no body parts are
in close proximity during the closing
procedure. 78
Side windows
Opening and closing
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When you lock the vehicle, you can
simultaneously:
R
close the side windows
R close the panorama roof with power tilt/
sliding panel
On vehicles with
a panorama roof with power
tilt/sliding panel, you can then close the
roller sunblinds.
i The SmartKey must be close to the
driver's door handle.
X Point the tip of the SmartKey at the driver's
door handle.
X Press and hold the & button until the
side windows and the panorama roof with
power tilt/sliding panel are fully closed.
X Make sure that all the side windows and the
panorama roof with power tilt/sliding
panel are closed.
On vehicles with a panorama roof with power
tilt/sliding panel:
X Press and hold the & button again
until
the roller sunblinds of the panorama roof
with power tilt/sliding panel close.
X To interrupt convenience closing:
release the & button.Resetting the side windows
You must reset each side window if:
R the side window opens again slightly after
being closed fully.
R the side window can no longer be fully
opened or closed.
X Close all the doors.
X Turn the SmartKey to position 1
or 2
in the
ignition lock.
X Pull the corresponding switch on the door
control panel until the side window is
completely closed ( Y page 77).
X Hold the switch for an additional second. If the side window opens again slightly:
X
Immediately
pull the corresponding switch
on the door control panel until the side
window is completely closed ( Y page 77).
X Hold the switch for an additional second.
X If the corresponding side window remains
closed after the button has been released,
the side window has been reset correctly.
If this is not the case, repeat the steps
above again. Problems with the side windows
G
WARNING
If you close a side window again immediately
after it has been blocked or reset, the side
window closes with increased or maximum
force. The reversing

feature is then not active.
Parts of the body could be trapped in the
closing area in the process. This poses an
increased risk of injury or even fatal injury.
Make sure that no parts of the body are in the
closing area. To stop the closing process,
release the switch or push the switch again to
reopen the side window.
Problem: a side window cannot be closed
because it is blocked by objects, e.g.
leaves in the window guide.
X Remove the objects.
X Close the side window.
Problem: a side window cannot be closed
and you cannot see the cause. If a side
window is obstructed during closing and
reopens again slightly:
X Immediately after the window blocks, pull
the corresponding switch again until the
side window has closed.
The side window is closed with increased
force. Side windows
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Operating the sliding sunroof
Overhead control panel
:
To raise
; To open
= To close/lower
X Turn the SmartKey to position 1 or
2 in the
ignition lock.
X Make sure that the roller sunblinds are
open.
X Press or pull the 3 switch in the
corresponding direction.
i If you press the 3 switch beyond the
point of resistance,

an automatic opening/
closing process is started in the
corresponding direction. You can stop
automatic operation by operating the
switch again.
The automatic raising feature is available
only when the sliding sunroof is closed.
i You can continue to operate the sliding
sunroof after switching off the engine or
removing the SmartKey from the ignition
lock. This function remains active for five
minutes or until you open a front door. Operating the roller sunblinds for the
sliding sunroof
Important safety notes G
WARNING
When opening or closing the roller sunblind,
parts of the body could be trapped between the roller sunblind and the frame or sliding
sunroof. There is a risk of injury.
When opening or closing make sure that no
parts of
the

body are in the sweep of the roller
sunblind.
If somebody becomes trapped:
R release the switch immediately, or
R during automatic operation, push the
switch briefly in any direction
The opening or closing procedure will be
stopped.
The roller sunblinds shield the vehicle interior
from sunlight. The two roller sunblinds can
only be opened and closed together when the
sliding sunroof is closed.
Roller sunblind reversing feature The roller sunblinds are equipped with an
automatic reversing feature. If a solid object
blocks or
restricts

a roller sunblind during the
closing process, the roller sunblind opens
again automatically. However, the automatic
reversing feature is only an aid and does not
relieve you of the responsibility of paying
attention when closing the roller sunblinds. G
WARNING
The reversing feature does not react:
R to soft, light and thin objects, e.g. small
fingers
R when closing the roller sunblind again
manually immediately after automatic
reversing
This means that the reversing feature cannot
prevent someone being trapped in these
situations. There is a risk of injury.
When closing make sure that no parts of the
body are in the sweep of the roller sunblind.
If somebody becomes trapped:
R release the switch immediately, or
R during automatic operation, push the
switch briefly in any direction
The closing process is stopped. Panorama roof with power tilt/sliding panel
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defroster is switched on and the outside
temperature is
low.
Mirror heating lasts up to
10 minutes.
i You can also heat up the exterior mirrors
manually by switching on the rear window
defroster.
Folding the exterior mirrors in or out
electrically X
Make sure that the SmartKey is in position
1 or 2 in the ignition lock.
X Briefly press button :.
Both exterior mirrors fold in or out.
i Make sure that the exterior mirrors are
always folded out fully while driving. They
could otherwise vibrate.
i If you are driving faster than
30 mph (47 km/h ), you can no longer fold
in the exterior mirrors.
Setting the exterior mirrors If the battery has been disconnected or
completely discharged, the exterior mirrors
must be reset. The exterior mirrors will
otherwise not fold in when you select the
"Fold in
mirrors

when locking" function in the
on-board computer (Y page 199).
X Make sure that the SmartKey is in
position 1 in the ignition lock.
X Briefly press button :. Folding the exterior mirrors in or out
automatically If the "Fold in mirrors when locking" function
is activated in the on-board computer
(Y page 199):
R
the exterior mirrors

fold in automatically as
soon as you lock the vehicle from the
outside.
R the exterior mirrors fold out again
automatically as soon as you unlock the
vehicle and then open the driver's or front-
passenger door.
i If the exterior mirrors have been folded in
manually, they do not fold out.
Exterior mirror pushed out of position If an exterior mirror has been pushed out of
position, proceed as follows:
X
Vehicles without electrically folding
exterior mirrors:
move

the exterior mirror
into the correct position manually.
X Vehicles with electrically folding
exterior mirrors: press and hold mirror-
folding button ( Y page

93) until you hear a
click and then the mirrors engage in
position.
The mirror housing is engaged again and
you can adjust the exterior mirrors as usual
(Y page 92). Automatic anti-glare mirrors
The "Automatic anti-glare

mirrors" function is
only available if the vehicle is equipped with
the "Mirrors package".
The rear-view mirror and the exterior mirror
on the driver's side automatically go into anti-
glare mode if:
R the ignition is switched on and
R incident light from headlamps strikes the
sensor in the rear-view mirror.
The mirrors do not go into anti-glare mode if
reverse gear is engaged or the interior lighting
is switched on. Mirrors
93
Seats, steering wheel and mirrors Z
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