key battery MERCEDES-BENZ A CLASS 2012 User Guide

the instrument cluster goes out. The
_
indicator lamp in the multifunction display
remains lit.
X To deactivate: move the combination
switch back to its normal position.
The _ indicator lamp in the multifunc-
tion display goes out. Headlamps misted up on the inside
The headlamps may mist up on the inside if
there is high atmospheric humidity.
X Switch on the lights and drive off.
The level of moisture diminishes, depend-
ing on the length of the journey and the
weather conditions (humidity and temper-
ature).
If the level of moisture does not diminish:
X Have the headlamps checked at a qualified
specialist workshop. Interior lighting
Overview of interior lighting
Front overhead control panel
:
p To switch the left-hand front reading
lamp on/off
; c To switch the front interior lighting
on
= v To switch the rear interior lighting
on/off
? |
To switch the front interior lighting/
automatic interior lighting control off A
p
To switch the right-hand front read-
ing lamp on/off
B To switch the automatic interior lighting
control on Rear-compartment overhead control panel
:
p
To switch the left-hand reading lamp
on/off
; p To switch the right-hand reading
lamp on/off Interior lighting control
Important notes In order to prevent the vehicle's battery from
discharging,

the interior lighting functions are
automatically deactivated after some time
except for when the key is in position 2 in the
ignition lock.
The brightness of the ambient lighting may be
set using the on-board computer
(Y page 222).
Automatic interior lighting control X
To switch on: set the switch to centre
position B.
X To switch off: set the switch to the |
position.
The interior lighting automatically switches
on if you:
R unlock the vehicle
R open a door
R remove the key from the ignition lock Interior lighting
111
Lights and windscreen wipers Z

Windows misted up on the outside
X
Activate the windscreen wipers.
X Set the air distribution to P or O.
i You should only select this setting until
the windscreen is clear again. Rear window heating
Switching on/off The rear window heating has a high current
draw. You should therefore switch it off as
soon as the window is clear. It otherwise
switches off automatically after several
minutes.
If
the battery voltage is too low, the rear win-
dow heating may switch off.
X Turn the key to position 2 in the ignition
lock (Y page 143).
X Press the ¤ button.
The

indicator lamp in the ¤ button lights
up or goes out. Operating the climate control system
131
Climate control

Problems with the rear window heating
Problem Possible causes/consequences and
M SolutionsThe rear window heat-
ing has switched off
prematurely or cannot
be activated. The battery has not been sufficiently charged.
X
Switch off any consumers that are not required, e.g. reading
lamps, interior lighting or the seat heating.
When
the battery is sufficiently charged, the rear window heat-
ing can be activated again. Activating/deactivating air-recircula-
tion mode
If you switch on air-recirculation mode, the
windows can mist up more quickly, in partic-
ular at low temperatures. Only use air-recir-
culation

mode briefly to prevent the windows
misting up.
You can deactivate the flow of fresh air if
unpleasant odours are entering the vehicle
from outside. The air already inside the vehi-
cle will then be recirculated.
The operation of air-recirculation mode is the
same for all control panels.
X Turn the key to position 2 in the ignition
lock (Y page 143).
X To activate: press the e button.
The
indicator lamp in the e button lights
up.
i Air-recirculation mode is activated auto-
matically at high outside temperatures.
When air-recirculation mode is activated
automatically, the indicator lamp in the
e button is not lit.
Outside air is added after about
30 minutes.
X To deactivate: press the e button.
The
indicator lamp in the e button goes
out. i
Air-recirculation mode deactivates auto-
matically:
R after approximately five minutes at out-
side temperatures below approximately
5 †.
R after approximately five minutes if the
"Cooling

with air dehumidification" func-
tion is deactivated.
R after approximately 30 minutes at out-
side temperatures above approximately
5 † and when the "Cooling with air dehu-
midification function" is activated. Convenience opening/closing using
the air-recirculation button
G
WARNING
When the convenience closing feature is oper-
ating,
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 oper-
ating. When closing make sure that no parts
of the body are in the closing area. G
WARNING
During convenience opening parts of the body
could be drawn in or become trapped
between

the side window and window frame.
There is a risk of injury.
When opening, make sure that nobody is
touching the side window. If someone
becomes trapped, press the W switch132
Operating the climate control system
Climate control

immediately to open/close the side window
in the door. The side window stops. To con-
tinue closing the side window, pull on the
W switch.
X Convenience closing feature: press and
hold the e button until the side win-
dows
and the panorama sliding sunroof are
closed.
The indicator lamp in the e button lights
up. Air-recirculation mode is activated.
If parts of the body are in the closing area
during convenience closing, proceed as fol-
lows:
X To open/close the side window, press the
W button.
The side window stops.
X To then open the side window, press the
W button again.
X To open/close the panorama sliding sun-
roof press the 3 button.
The panorama sliding sunroof stops.
X To then open the panorama sliding sunroof
press the 3 button again.
X Press the d
button again for longer than
2 seconds.
The side windows move in the opposite
direction.
i Notes on the automatic reversing func-
tion for:
R the side window

(Y page 84)
R the panorama sliding sunroof
(Y page 87)
X Convenience opening feature:
press and
hold the e button until the side win-
dows and the panorama sliding sunroof
have opened. The side windows and the
panorama sliding sunroof move back to
their original position.
The indicator lamp in the e button goes
out. Air-recirculation mode is deactivated.
i If you open the side windows or the pan-
orama sliding sunroof manually after clos-
ing with the convenience closing feature, they will remain in this position when
opened

using the convenience opening fea-
ture. Activating/deactivating the residual
heat function
The residual heat function is only available
with

THERMOTRONIC automatic climate con-
trol.
It is possible to make use of the residual heat
of the engine to continue heating the vehicle
for approximately 30 minutes after the engine
has been switched off. The heating time
depends on the temperature that has been
set for the vehicle interior.
i The blower will run at a low speed regard-
less of the airflow setting.
i If you activate the residual heat function
at high temperatures, only the ventilation
will be activated. The blower runs at
medium speed.
X Turn the key to position 0 in the ignition
lock or remove it ( Y page 143).
X To activate: press the Ì button.
The
indicator lamp in the Ì button lights
up.
X To deactivate: press the Ì button.
The
indicator lamp in the Ì button goes
out.
i Residual heat is deactivated automati-
cally:
R after approximately

30 minutes
R when the ignition is switched on
R if the battery voltage drops
R when the auxiliary heating is switched on Operating the climate control system
133
Climate control Z

Auxiliary heating
Important safety notes G
DANGER
If the exhaust pipe is blocked or sufficient
ventilation is not possible, toxic exhaust
fumes can enter the vehicle, especially car-
bon monoxide. This is the case, e.g. in
enclosed spaces, or if the vehicle is stuck in
snow. There is a risk of fatal injuries.
You should switch off the auxiliary heating in
enclosed
spaces which do not have an extrac-
tion system, e.g. a garage. If the vehicle is
stuck in snow and you must leave the auxiliary
heating running, keep the exhaust pipe and
the area around the vehicle clear of snow. To
guarantee a sufficient supply of fresh air, open
a window on the side of the vehicle away from
the wind. G
WARNING
When the auxiliary heating is switched on,
parts of the vehicle can become very hot.
Flammable material such as leaves, grass or
twigs

may ignite if they come into contact with
hot parts of the exhaust system for extended
periods. There is a risk of fire.
When the auxiliary heating is switched on,
make sure that no flammable material can
come into contact with hot vehicle compo-
nents.
! Operating the auxiliary heating/ventila-
tion draws on the vehicle battery. After you
have heated or ventilated the vehicle a
maximum of two times, drive for a longer
distance.
i Switch the auxiliary heating on regularly
once a month for about ten minutes.
The auxiliary heating heats the air in the vehi-
cle interior to the set temperature. This
occurs without using the heat of the running
engine. The auxiliary heating is operated
directly using the vehicle's fuel. For this rea-
son, the fuel tank must be at least ¼ full to
ensure that the auxiliary heating functions. The auxiliary heating/ventilation automati-
cally adjusts to changes in temperature and
weather

conditions. For this reason, the aux-
iliary heating could switch from ventilation
mode to heating mode or from heating mode
to ventilation mode.
The auxiliary heating switches off when the
engine is switched off. The auxiliary ventila-
tion switches off when you turn the key to key
position 2(Y page 143).
The auxiliary heating switches off automati-
cally after 30 minutes.
You cannot use the auxiliary ventilation to
cool the vehicle interior to a temperature
lower than the outside temperature.
Before switching on X
Turn the key to position 2 in the ignition
lock (Y page 143).
X Set the desired temperature.
Auxiliary heating or ventilation can also be
switched on if the manually set climate con-
trol is activated. Optimum comfort can be
attained

when the system is set to automatic
mode. Set the temperature to 22 †.
The auxiliary heating/ventilation can be acti-
vated or deactivated using the remote control
or the button on the centre console.
The on-board computer can be used to spec-
ify up to three departure times, one of which
may be preselected ( Y page 224).134
Operating the climate control systemClimate control

Important safety notes
G
WARNING
If the engine is switched off automatically and
you exit the vehicle, the engine is restarted
automatically.
The vehicle may begin moving.
There is a risk of accident and injury.
If you wish to exit the vehicle, always turn off
the ignition and secure the vehicle against
rolling away.
General notes :
ECO start/stop display
If the ¤ symbol is shown in green in the
multifunction display, the ECO start/stop
function switches the engine off automati-
cally if the vehicle stops moving.
The

stop/start function is automatically acti-
vated each time you start the engine with the
ignition key.
If the ECO start/stop function has been man-
ually deactivated ( Y page 147) or a malfunc-
tion has caused the system to be deactivated,
the ¤ symbol is not displayed.
AMG vehicles: the ECO start/stop function
is only available in drive program C.
Automatic engine switch-off General notes
The ECO start/stop function is operational
and the
¤ symbol is displayed in green in
the multifunction display, if:
R the indicator lamp in the ECO button is lit
green
R the

outside temperature is within the range
that is suitable for the system R
the engine is at normal operating temper-
ature
R the

set temperature for the vehicle interior
has been reached
R the battery is sufficiently charged
R the system detects that the windscreen is
not misted up when the air-conditioning
system is switched on
R the bonnet is closed
R the driver's door is closed and the driver's
seat belt is fastened
If not all conditions for automatic engine
switch-off are fulfilled, the ¤ symbol is
shown in yellow.
i All of the vehicle's systems remain active
when the engine is switched off automati-
cally.
i The engine can be switched off automat-
ically a maximum of four times (initial stop,
then three subsequent stops) in succes-
sion. The ¤ symbol is shown in yellow
in the multifunction display after the engine
has been started automatically for the
fourth time. When the ¤ symbol is
shown in green in the multifunction display,
automatic engine switch-off is again possi-
ble.
Vehicles with manual transmission
The ECO start/stop function switches off the
engine automatically at low speeds. X
Brake the vehicle.
X Engage neutral N(Y page 151) (follow
gearshift instruction : to engage neutral
N, if necessary).
X Release the clutch pedal.
The engine is switched off automatically.146
Driving
Driving and parking

Problems with the engine
Problem Possible causes/consequences and
M SolutionsThe engine does not
start. The HOLD function or DISTRONIC PLUS is activated.
X
Deactivate the HOLD function (Y page 179) or DISTRONIC
PLUS (Y page 173).
X Try to start the engine again. The engine does not
start.
The starter motor
can be heard. R
There is a malfunction in the engine electronics.
R There is a malfunction in the fuel supply.
X Turn the key back to position 0 in the ignition lock before
attempting to start the engine again.
X Try to start the engine again (Y page 143). Avoid excessively
long

and frequent attempts to start the engine, as this will drain
the battery.
If the engine does not start after several attempts:
X Consult a qualified specialist workshop. The engine does not
start.

The starter motor
can be heard. The
reserve fuel warning
lamp is lit and the fuel
gauge display shows 0. The fuel tank is empty.
X
Refuel the vehicle. The engine does not
start. You cannot hear
the starter motor. The on-board voltage is too low because the battery is too weak
or discharged.
X
Jump-start the vehicle (Y page 308).
If the engine does not start despite attempts to jump-start it:
X Consult a qualified specialist workshop. The starter motor was exposed to a thermal load that was too high.
X
Allow the starter motor to cool down for approximately two
minutes.
X Try to start the engine again.
If the engine still does not start:
X Consult a qualified specialist workshop, e.g. a Mercedes-Benz
Service Centre. Driving
149
Driving and parking Z

Problem Possible causes/consequences and
M SolutionsThe fuel filler flap can-
not be opened. The fuel filler flap is not unlocked.
or
The key battery is discharged.
X
Unlock the vehicle (Y page 75).
or
X Unlock the vehicle using the emergency key element
(Y page 75). The fuel filler flap is unlocked, but the opening mechanism is jam-
med.
X
Consult a qualified specialist workshop. Parking
Important safety notes
G
WARNING
Flammable material such as leaves, grass or
twigs may ignite if they come into contact with
hot parts of the exhaust system or exhaust
gas flow. There is a risk of fire.
Park the vehicle so that no flammable mate-
rial can come into contact with hot vehicle
components. In particular, do not park on dry
grassland or harvested grain fields. G
WARNING
If you leave children unattended in the vehi-
cle, they may be able to set the vehicle in
motion if, for example, they:
R release the parking brake
R shift

the automatic transmission out of park
position P or shift manual transmission into
neutral
R start the engine
In addition, they may operate vehicle equip-
ment and become trapped. There is a risk of
an accident and injury.
When leaving the vehicle, always take the key
with you and lock the vehicle. Never leave
children unattended in the vehicle. !
Always secure the vehicle correctly
against

rolling away. Otherwise, the vehicle
or its drivetrain could be damaged.
To ensure that the vehicle is secured against
rolling away unintentionally:
R the electric parking brake must be applied.
R on vehicles with manual transmission,
engage first gear or reverse gear.
R on vehicles with automatic transmission,
the transmission must be in position P and
the transmission position display must
show P in the multifunction display.
R the key must be removed from the ignition
lock.
R on uphill or downhill gradients, the front
wheels must be turned towards the kerb. Switching off the engine
Important safety notes G
WARNING
The automatic transmission switches to neu-
tral
position N when you switch off the engine.
The vehicle may roll away. There is a risk of
an accident.
After switching off the engine, always switch
to parking position P. Prevent the parked vehi-162
Parking
Driving and parking

Releasing
X
Pull handle :.
The red ! indicator lamp in the instru-
ment cluster goes out.
i You can only release the electric parking
brake when the key is in position 1 or 2 in
the ignition lock.
Applying automatically The electric parking brake is applied auto-
matically:
R
if DISTRONIC PLUS brings the vehicle to a
standstill (vehicles with automatic trans-
mission) or
R if
the HOLD function is keeping the vehicle
stationary.
In addition, at least one of the following con-
ditions must be fulfilled:
R the engine is switched off
R the driver's door is open and the seat belt
is not fastened
R there is a system malfunction
R the power supply is insufficient
R the vehicle is stationary for a lengthy
period.
The red ! indicator lamp in the instrument
cluster lights up.
i The electric parking brake is not automat-
ically applied if the engine is switched off
by the ECO start/stop function.
Releasing automatically i
The electric parking brake can only be
released automatically in vehicles with
automatic transmission.
The electric parking brake of your vehicle is
released

automatically when all of the follow-
ing conditions are fulfilled:
R the engine is running.
R the transmission is in position D or R.
R the seat belt is fastened.
R you depress the accelerator pedal. If the transmission is in position
R,
the tailgate
must be closed.
If your seat belt is not fastened, the following
conditions must be fulfilled to automatically
release the electric parking brake:
R the driver's door is closed.
R you have shifted out of transmission posi-
tion P or you have previously driven faster
than 3 km/h.
Emergency braking The vehicle can also be braked during an
emergency using the electric parking brake.
X
While driving, push handle :
of the electric
parking brake ( Y page 163).
i The vehicle is braked for as long as han-
dle : of the electric parking brake
pressed. The longer the electric parking
brake handle : is depressed, the greater
the braking force.
During braking:
R a warning tone sounds
R the Release parking brake message
appears
R the red ! indicator lamp in the instru-
ment cluster flashes
When

the vehicle has been braked to a stand-
still, the electric parking brake is engaged. Parking up the vehicle
If you leave the vehicle parked up for longer
than

four weeks, the battery may be damaged
by exhaustive discharging.
If you leave the vehicle parked up for longer
than six weeks, the vehicle may suffer dam-
age as a result of lack of use.
X Visit a qualified specialist workshop and
seek advice.
i You can obtain information about trickle
chargers from a qualified specialist work-
shop. 164
Parking
Driving and parking

X
Press the ball coupling in the direction of
the arrow until it engages behind the
bumper.
Indicator lamp ? goes out and the mes-
sage in the multifunction display disap-
pears. Trailer power supply
! You can connect accessories with a
power rating of up to 240 W to the perma-
nent
power supply and with a power rating
of up to 180 W to the power supply that is
switched on via the ignition lock.
The trailer battery may not be charged from
the power supply.
X To switch the connected power supply
on or off: turn the key in the ignition lock
to position 2 or 0 respectively.
When it leaves the factory, your vehicle's
trailer socket is equipped with a permanent
power supply and a power supply that is
switched on via the ignition lock.
The permanent power supply is supplied via
trailer socket pin 9.
The power supply that is switched on via the
ignition lock is supplied via trailer socket pin
10.
The trailer's permanent power supply is
switched

off in the event of low vehicle supply
voltage and after six hours at the latest.
You can find more information about instal-
ling the trailer electrics at a qualified special-
ist workshop. Bulb failure indicator for LED lamps
i If LED lamps are fitted in the trailer, an
error message may appear in the multi-
function

display even if there is no fault. The
reason for the error message could be that
the current has fallen below the minimum
of 50 mA. To ensure reliable operation of the bulb failure
indicator,

each LED chain in the trailer lighting
must be guaranteed a minimum current of
50 mA. Trailer with 7-pin connector
General notes Trailer with 7-pin connector: you can con-
nect

to the 13-pin socket on the ball coupling
using an adapter or, if necessary, an adapter
cable. Both can be obtained at a qualified
specialist workshop.
Fitting the adapter !
Make sure that there is sufficient cable
play so that the cable cannot become
detached when cornering.
! Remove the installed adapter cable
before folding in the ball coupling. Other-
wise, damage may occur to the rear
bumper and the adapter cable. X
Open the socket cover.
X Insert the plug connector with lug : into
groove =

on the socket. Turn bayonet con-
nection ; clockwise to the stop.
X Let the cover engage.
X If you are using an adapter cable, secure
the cable to the trailer with cable ties.206
Towing a trailer
Driving and parking