brake MERCEDES-BENZ A CLASS 2012 Repair Manual

The electric parking brake secures the vehicle
automatically if the HOLD function is activa-
ted and:
R
the driver's door is open and the driver's
seat belt is unfastened
R the
engine is switched off, unless it is auto-
matically switched off by the ECO start/
stop function
R a system fault occurs
R the power supply is not sufficient
Vehicles with automatic transmission
If a fault occurs, then the transmission may
also be shifted into position P automatically.
Vehicles with manual transmission
The Brake immediately message can also
appear in the multifunction display.
X Immediately depress the brake pedal firmly
until

the warning message in the multifunc-
tion display goes out.
The HOLD function is deactivated.
A horn will sound at regular intervals if you
turn off the engine, take off your seat belt or
open the driver's door when the HOLD func-
tion is activated. The horn alerts you to the
fact that the HOLD function is still activated.
If you attempt to lock the vehicle, the tone
becomes louder. The vehicle cannot be
locked until you have deactivated the HOLD
function.
i Once you have switched off the engine,
you cannot restart it until you have deacti-
vated the HOLD function. RACE START
Important safety notes RACE START enables optimum acceleration
from a standing start. The precondition for
this is a suitable high-grip road surface.
Only

activate RACE START on dedicated race
circuits. i
RACE
START is only available in AMG vehi-
cles.
Activation conditions You can activate RACE START if:
R
the doors, the bonnet and the tailgate are
closed
R the

engine is running and the transmission,
traction control and engine are at operating
temperature
R SPORT handling mode is activated
(Y page 66)
R the steering wheel is in the straight-ahead
position.
R the vehicle is stationary and the brake
pedal is depressed (left foot)
R the transmission is in position D.
R drive program M is selected ( Y page 155).
Activating RACE START X
Depress the brake pedal with your left foot
and keep it depressed.
X Pull and hold both steering wheel gearshift
paddles.
X The RACE START Confirm: Paddle UP
Cancel: Paddle DOWN message appears
in the multifunction display.
X Release both steering wheel gearshift pad-
dles.
i If the activation conditions are no longer
fulfilled, RACE START is cancelled. The
RACE START not possible See Own‐
er's

Manual message appears in the mul-
tifunction display.
X To cancel:
pull the left steering wheel shift
paddle (Y page 156).
or
X To confirm: pull the right steering wheel
shift paddle

(Y page 156).
The RACE START available Depress
accelerator message appears in the mul-
tifunction display. Driving systems
181
Driving and parking Z

i
If you do not depress the accelerator
pedal
within a few seconds, RACE START is
cancelled. The multifunction display shows
the RACE START cancelled message.
X Fully depress the accelerator pedal.
The engine speed is increased.
The RACE START Release brake to
start message appears in the multifunc-
tion display.
i If the brake pedal is not released after a
short while, RACE START is cancelled. The
multifunction display shows the RACE
START cancelled message.
X Take your foot off the brake, but keep the
accelerator pedal depressed.
The vehicle pulls away at maximum accel-
eration.
The RACE

START active message appears
in the multifunction display.
RACE START is deactivated when the vehicle
reaches a speed of approximately
50 km/h.
Drive program S is activated. SPORT handling
mode remains activated.
RACE START is deactivated immediately if
you release the accelerator pedal during
RACE START or if any of the activation condi-
tions are no longer fulfilled. The RACE START
not possible or RACE START cancelled
message appears in the multifunction dis-
play.
i After using it several times in short suc-
cession, RACE START will be unavailable
until a certain distance has been driven. 4MATIC (permanent all-wheel drive)
4MATIC ensures that all four wheels are per-
manently driven. Together with ESP ®
, it
improves the traction of your vehicle when-
ever a drive wheel spins due to insufficient
grip.
If

you fail to adapt your driving style, 4MATIC
can neither reduce the risk of accident nor
override the laws of physics. 4MATIC cannot take account of road, weather and traffic con-
ditions. 4MATIC is only an aid. You are
responsible for the distance to the vehicle in
front, for vehicle speed, for braking in good
time, and for staying in the lane.
If

a drive wheel spins due to insufficient grip:
R when pulling away, only depress the accel-
erator pedal as far as is necessary.
R accelerate less when driving.
! Never tow the vehicle with one axle
raised. This may damage the transfer case.
Damage of this sort is not covered by the
Mercedes-Benz implied warranty. All
wheels must remain either on the ground
or be fully raised. Observe the instructions
for towing the vehicle with all wheels in full
contact with the ground.
i In wintry driving conditions, the maximum
effect of 4MATIC can only be achieved if
you use winter tyres (M+S tyres), with snow
chains if necessary. PARKTRONIC
Important safety notes PARKTRONIC is only an aid. It is not a substi-
tute for your attention to the immediate sur-
roundings. The responsibility for safe
manoeuvring and parking remains with you.
Make

sure that there are no persons, animals
or objects in range while manoeuvring and
parking.
! When parking, pay particular attention to
objects above or below the sensors, such
as flower pots or trailer drawbars. PARK-
TRONIC does not detect such objects when
they are in the immediate vicinity of the
vehicle. You could damage the vehicle or
the objects.
The sensors may not detect snow and
objects which absorb ultrasonic sources.
Ultrasonic sources, such as an automatic
car wash, a lorry's compressed-air brakes 182
Driving systems
Driving and parking

or a pneumatic drill, could cause PARK-
TRONIC to malfunction.
PARKTRONIC
may not function correctly on
uneven terrain.
PARKTRONIC is an electronic parking aid with
ultrasonic sensors. It indicates visually and
audibly the distance between your vehicle
and an object.
PARKTRONIC is activated automatically if
you:
R switch on the ignition
R shift to position D, R or N on vehicles with
automatic transmission
R release the electric parking brake
PARKTRONIC is deactivated at speeds above
18 km/h. It is reactivated at lower speeds.
PARKTRONIC monitors the area around your
vehicle using six sensors in the front bumper
and four sensors in the rear bumper.
Range of the sensors General notes
PARKTRONIC does not take into account
obstacles located:
R
below the detection range, e.g. persons,
animals or objects
R above the detection range, e.g. overhang-
ing loads, tail sections or loading ramps of
goods vehicles :
Example: sensors in the front bumper,
left-hand side Side view
Top view
The sensors must be free of dirt, ice and
slush. Otherwise, they may not function cor-
rectly. Clean the sensors regularly, taking
care not to scratch or damage them
(Y page 294).
Front sensors
Centre Approx. 100 cm
Corners Approx. 60 cm
Rear sensors
Centre Approx. 120 cm
Corners Approx. 80 cm
Minimum distance
Centre Approx. 20 cm
Corners Approx. 20 cm
If there is an obstacle within this range, the
relevant

warning displays light up and a warn-
ing tone sounds. If the distance falls below
the minimum, the distance may no longer be
shown. Driving systems
183
Driving and parking Z

When driving at speeds below 30 km/h, you
will see parking symbol
; as a status indi-
cator
in the instrument cluster. When a park-
ing space has been detected, an arrow
towards the right or the left also appears.
Active Parking Assist only displays parking
spaces on the front-passenger side as stand-
ard. Parking spaces on the driver's side are
displayed as soon as the turn signal on the
driver's side is activated. When parking on the
driver's side, this must remain switched on
until you acknowledge the use of Active Park-
ing Assist by pressing the a button on the
multifunction steering wheel.
A parking space is displayed while you are
driving past it, and until you are approx-
imately 15 m away from it.
Parking G
WARNING
Active Parking Assist merely aids you by inter-
vening
actively in the steering. There is a risk
of accident if you do not apply the brakes
yourself.
Always apply the brakes yourself when park-
ing and manoeuvring.
Active Parking Assist does not support you
with parking spaces parallel to the direction
of travel if:
R the parking space is on a kerbstone
R the parking space is apparently blocked,
for example by foliage or grass paving
blocks
R the range of movement is too small
R the parking space is bordered by an obsta-
cle which is not clearly defined such as a
tree or a trailer
X Stop the vehicle when the parking symbol
shows the desired parking space in the
instrument cluster.
X Vehicles with manual transmission: shift to
reverse gear. Vehicles with automatic transmission: shift
into position R.
The Start Park Assist? Yes: OK No:
%

message appears in the multifunction
display.
X To cancel the procedure: press the
% button on the multifunction steering
wheel or pull away.
or
X To park using Active Parking Assist:
press

the a button on the multifunction
steering wheel.
The Park Assist active Accelerate
and brake Observe surroundings mes-
sage appears in the multifunction display.
X Release the multifunction steering wheel.
X Reverse the vehicle, being ready to brake
at all times. Do not exceed a maximum
speed of approximately

10 km/h when
reversing. Otherwise, Active Parking Assist
will be cancelled.
i In tight parking spaces, you will achieve
the best parking results by backing up as
far as possible. When doing so, also
observe the PARKTRONIC messages.
X Stop as soon as PARKTRONIC sounds the
continuous warning tone, if not before.
Manoeuvring

may be required in tight park-
ing spaces.
Vehicles with manual transmission: the Park
Assist active Engage forward gear
Observe

surroundings message appears in
the multifunction display.
Vehicles with automatic transmission: the
Park Assist active Select D Observe
surroundings message appears in the mul-
tifunction display.
X Vehicles with manual transmission: while
the vehicle is stationary, shift to first gear.
Vehicles with automatic transmission:
select transmission position D while the
vehicle is stationary.
Active

Parking Assist immediately steers in
the other direction. 188
Driving systems
Driving and parking

The Park Assist active Accelerate
and
brake Observe surroundings mes-
sage appears in the multifunction display.
i You will achieve the best results by wait-
ing

for the steering procedure to complete
before pulling away.
X Drive forwards and be ready to brake at all
times.
X Stop as soon as PARKTRONIC sounds the
continuous warning tone, if not before.
Vehicles with manual transmission: the Park
Assist active Engage reverse gear
Observe

surroundings message appears in
the multifunction display.
Vehicles with automatic transmission: the
Park Assist active Select R Observe
surroundings message appears in the mul-
tifunction display.
X Additional transmission shifts may be nec-
essary.
As soon as the parking procedure is com-
plete, the Park Assist switched off
message appears in the multifunction dis-
play.
Active Parking Assist is then deactivated.
PARKTRONIC is still available.
X Manoeuvre if necessary.
X Always observe the warning messages dis-
played by PARKTRONIC

(Y page 184).
Parking tips:
R the way your vehicle is positioned in the
parking space after parking is dependent
on various factors. These include the posi-
tion and shape of the vehicles parked in
front

and behind it and the conditions of the
location. It may be the case that Active
Parking Assist guides you too far into a
parking space, or not far enough into it. In
some cases, it may also lead you across or
onto the kerb. If necessary, you should can-
cel the parking procedure with Active Park-
ing Assist.
R you can also engage forward gear prema-
turely. The vehicle redirects and does not
drive as far into the parking space. Should a gear be changed too early, the parking
procedure will be cancelled. A sensible
parking

position can no longer be achieved
from this position.
Exiting a parking space In order that Active Parking Assist can sup-
port you when you exit the parking space:
R
the border of the parking space must not
be too low.
R the border of the parking space must not
be too wide. The system manoeuvres the
vehicle

into a position at a maximum of 45°
to the starting position in the parking
space.
R a manoeuvring distance of at least 0.60 m
must be available.
Active Parking Assist can only assist you with
exiting a parking space if you have parked the
vehicle using Active Parking Assist.
X Start the engine.
X Switch on the turn signal on the side facing
the street.
X Vehicles with manual transmission:
engage first or reverse gear.
Vehicles with automatic transmission:
shift the transmission to position D or R.
The Start Park Assist? Yes: OK No:
%

message appears in the multifunction
display.
X To cancel the procedure: press the
% button on the multifunction steering
wheel or pull away.
or
X To exit a parking space using Active
Parking Assist: press the a button on
the multifunction steering wheel.
The Park Assist active Accelerate
and

brake Observe surroundings mes-
sage appears in the multifunction display.
X Release the multifunction steering wheel.
X Reverse the vehicle or drive forwards, being
ready to brake at all times. Do not exceed
a maximum speed of approximately Driving systems
189
Driving and parking Z

10 km/h when exiting a parking space.
Otherwise, Active Parking Assist will be
cancelled.
X Stop when PARKTRONIC sounds the con-
tinuous warning tone, if not before.
X Vehicles with manual transmission:
shift to first or reverse gear as required
while the vehicle is stationary.
Vehicles with automatic transmission:
shift
to position D or R as required while the
vehicle is stationary.
Active Parking Assist immediately steers in
the other direction. The Park Assist
active Accelerate and brake
Observe surroundings message appears
in the multifunction display.
i You will achieve the best results by wait-
ing

for the steering procedure to complete
before pulling away.
If you reverse after activation, the steering
wheel is moved to the straight-ahead posi-
tion.
X Drive forwards or reverse the vehicle, being
ready to brake at all times.
X Stop as soon as PARKTRONIC sounds the
continuous warning tone, if not before.
X Drive forwards and reverse as prompted by
the

PARKTRONIC warning displays, several
times if necessary.
Once you have exited the parking space com-
pletely, the steering wheel is moved to the
straight-ahead position. You hear a tone and
the Park Assist switched off message
appears

in the multifunction display. You will
then have to steer and merge into traffic on
your own. PARKTRONIC is still available. Cancelling Active Parking Assist You can cancel Active Parking Assist at any
time.
X
Stop the movement of the multifunction
steering wheel or steer yourself.
Active Parking Assist will be cancelled at
once. The Park Assist cancelled mes-
sage appears in the multifunction display.
or
X Press the PARKTRONIC button on the
centre console

(Y page 185).
PARKTRONIC is switched off and Active
Parking Assist is immediately cancelled.
The Park Assist cancelled message
appears in the multifunction display.
Active Parking Assist is cancelled automati-
cally if:
R you engage the electric parking brake.
R parking using Active Parking Assist is no
longer possible.
R you are driving faster than 10 km/h.
R a

wheel spins and ESP ®
intervenes or fails.
The ÷ warning lamp lights up in the
instrument cluster.
A warning tone sounds. The parking space
symbol disappears and the multifunction dis-
play shows the Park Assist cancelled
message.
When Active Parking Assist is cancelled, you
must steer again yourself.
If a system malfunction occurs, the vehicle is
braked to a standstill. To drive on, depress the
accelerator again.
Towing a trailer For vehicles with a trailer tow hitch, the min-
imum required length for parking spaces is
slightly increased.
If you have attached a trailer to your vehicle,
you should not use Active Parking Assist.
Once

the electrical connection is established
between your vehicle and the trailer, Active
Parking Assist is no longer available. PARK-
TRONIC is deactivated for the rear area. 190
Driving systems
Driving and parking

:
Lane Keeping Assist camera
If you select km on the on-board computer in
the Display unit Speed-/odometer func-
tion (Y page 220), Lane Keeping Assist is
active starting at a speed of 60 km/h
. If the
miles display unit is selected, the assistance
range begins at 40 mph.
Important safety notes G
WARNING
Lane Keeping Assist cannot always clearly
identify lane markings.
In these cases, Lane Keeping Assist may:
R give an unnecessary warning
R not give a warning
There is a risk of an accident.
Always pay particular attention to the traffic
situation and keep in lane, especially if Lane
Keeping Assist alerts you. G
WARNING
The Lane Keeping Assist warning does not
return the vehicle to the original lane. There
is a risk of an accident.
Always steer, apply the brakes or accelerate
the vehicle yourself, especially if Lane Keep-
ing Assist alerts you.
If you fail to adapt your driving style, Lane
Keeping

Assist can neither reduce the risk of
an accident nor override the laws of physics.
Lane Keeping Assist cannot take into account
road, weather or traffic conditions. Lane
Keeping Assist is only an aid. You are respon-
sible for the distance to the vehicle in front, for vehicle speed, for braking in good time,
and for staying in the lane.
Lane

Keeping Assist does not keep your vehi-
cle in its lane.
The system may be impaired or may not func-
tion if:
R there is poor visibility, e.g. due to insuffi-
cient illumination of the road, or due to
snow, rain, fog or spray
R there is glare, e.g. from oncoming traffic,
the sun or reflection from other vehicles
(e.g. if the road surface is wet)
R the windscreen is dirty, misted up, dam-
aged or covered, for instance by a sticker
in the vicinity of the camera
R no, or several, unclear lane markings are
present for one lane, e.g. in a construction
area
R the lane markings are worn away, dark or
covered up, e.g. by dirt or snow
R the distance to the vehicle in front is too
small and the lane markings thus cannot be
detected
R the lane markings change quickly, e.g.
lanes branch off, cross one another or
merge
R the road is narrow and winding
R there are highly variable shade conditions
on the road
A warning may be given if a front wheel
passes over a lane marking. It will warn you
by means of intermittent vibration in the
steering wheel for up to 1.5 seconds.
Activating Lane Keeping Assist
X Activate Lane Keeping Assist using the on-
board computer; to do so, select Stand‐
ard or Adaptive(Y page 219).
If you drive at speeds above

60 km/h and
lane markings are detected, the lane mark-
ings in the assistance graphics display
(Y page 217) are shown in green. 200
Driving systems
Driving and parking

When
Standard is selected, no warning vibra-
tion occurs if:
R you have switched on the turn signals. In
this event, the warnings are suppressed for
a certain period of time.
R a driving safety system intervenes, such as
ABS, BAS or ESP ®
.
When Adaptive is selected, no warning vibra-
tion occurs if:
R you have switched on the turn signals. In
this case, the warnings are suppressed for
a certain period of time.
R a driving safety system intervenes, such as
ABS, BAS or ESP ®
.
R you accelerate hard, e.g. kickdown.
R you brake hard.
R you steer actively, e.g. swerve to avoid an
obstacle or change lane quickly.
R you cut the corner on a sharp bend.
In order that you are warned only when nec-
essary and in good time if you cross the lane
marking, the system recognises certain con-
ditions and warns you accordingly.
The warning vibration occurs earlier if:
R you approach the outer lane marking on a
bend.
R the road has very wide lanes, e.g. a motor-
way.
R the system recognises solid lane markings.
The warning vibration occurs later if:
R the road has narrow lanes.
R you cut the corner on a bend. Towing a trailer
Notes on towing a trailer
Important safety notes G
WARNING
The braking system can overheat if you leave
your foot on the brake pedal while driving.
This

increases the braking distance and could even cause the braking system to fail. There
is a risk of an accident.
Never use the brake pedal as a footrest. Do
not simultaneously depress both the brake
pedal

and the accelerator pedal while driving. G
WARNING
You could lose control of the vehicle/trailer
combination if it begins to swerve. The vehi-
cle/trailer combination could even overturn.
There is a risk of an accident.
On no account should you attempt to
straighten out the vehicle/trailer combina-
tion by increasing speed. Decrease your
speed and do not countersteer. Brake if nec-
essary. G
WARNING
If the maximum the permissible load for a car-
rier system is exceeded, the carrier could
come loose from the vehicle and endanger
other

road users. There is a risk of an accident
and injury.
Never exceed the permissible noseweight
when using a carrier.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
Trailer towing is not permissible on the fol-
lowing models:
R A 45 AMG 4MATIC
R Vehicles with the AMG Sports package
If you exceed the maximum permissible nose-
weight of the trailer drawbar on the ball cou-
pling, the following may become damaged:
R your vehicle
R the trailer
R the ball coupling
R the trailer tow hitch
The vehicle/trailer combination could
become unstable.
If the noseweight used is lower than the min-
imum permissible noseweight, the vehicle/ Towing a trailer
201
Driving and parking Z

prescribed maximum speed in the relevant
country.
For
certain Mercedes-Benz vehicles, the max-
imum permissible rear axle load is increased
when towing a trailer. Refer to the "Technical
data" section to find out whether this applies
to your vehicle. If you utilise any of the added
maximum rear axle load when towing a trailer,
the vehicle/trailer combination may not
exceed a maximum speed of 100 km/h for
reasons concerning the operating permit.
This also applies in countries in which the
permissible maximum speed for vehicle/
trailer combinations is above 100 km/h.
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
to when driving without a trailer and it will
consume more fuel.
Change into a lower gear in good time on long
and steep downhill gradients. For vehicles
with automatic transmission, you need to
have selected manual drive program
M(Y page 156).
i This also applies if you have activated
cruise control, SPEEDTRONIC or DIS-
TRONIC PLUS.
This will use the braking effect of the engine,
so less braking will be required to maintain
vehicle speed. This relieves the load on the
brake system and prevents the brakes from
overheating and wearing too quickly. If you
need additional braking, depress the brake
pedal repeatedly rather than continuously.
i Briefly depressing the accelerator pedal
on downhill gradients while the manual
drive program M is temporarily activated
(vehicles with automatic transmission): the
automatic transmission may switch back to
the last active automatic drive program E
or S. The automatic transmission may shift
to a higher gear. This can reduce the
engine's braking effect. Driving tips If the trailer swings from side to side:
X
Do not accelerate.
X Do not countersteer.
X Brake if necessary.
R Maintain a greater distance from the vehi-
cle in front than when driving without a
trailer.
R Avoid braking abruptly. If possible, brake
gently

at first to allow the trailer to run on.
Then, increase the braking force rapidly.
R The values given for gradient-climbing
capabilities from a standstill refer to sea
level. When driving in mountainous areas,
note that the power output of the engine,
and consequently the vehicle's gradient-
climbing capability, decrease with increas-
ing altitude. Folding out the ball coupling
G
WARNING
If you release the ball coupling or it does not
engage
correctly when folding in, it will swing
out. Within pivoting range of the ball coupling,
there is an increased risk of an accident and
injury.
Only release the ball coupling if the pivoting
range is unobstructed. Always make sure that
the ball coupling engages when folding in.
Before you can tow a trailer with your vehicle,
you must fold out the ball coupling.
The release wheel is located behind the left-
hand side trim panel in the boot. Towing a trailer
203
Driving and parking Z

X
To open the cover: turn handle : anti-
clockwise and fold down cover ; and
remove it. X
Pull out release wheel =.
X Turn release wheel = anti-clockwise as far
as it will go.
The ball coupling disengages and folds out
behind the rear bumper. Indicator
lamp ? flashes. G
WARNING
If the ball coupling is not correctly engaged,
the trailer can detach. There is a risk of an
accident.
Always

engage the ball coupling as described.
X Pull the ball coupling in the direction of the
arrow

until it engages in a vertical position.
Indicator lamp ? goes out. The power
socket folds down automatically.
The multifunction display shows the
Check trailer hitch lock display mes-
sage until the ball coupling is engaged.
X Remove the protective covering from the
ball coupling and store it in a safe place.
X Make sure that the ball of the ball coupling
is clean and that it is either greased or dry
(grease free), depending on the instruc-
tions for the trailer. Coupling up a trailer
X Make sure that the transmission is in posi-
tion P.
X Apply the electric parking brake.
X Position the trailer level behind the vehicle.
X Couple up the trailer.
X Establish the electric connection between
the vehicle and the trailer.
X Check that the trailer lighting system is
working.
A trailer that is connected is recognised
only when the electrical connection is
established

correctly and when the lighting
system is working properly. The function of
other systems, such as ESP ®
or PARK-
TRONIC also depends on this. Uncoupling a trailer
G
WARNING
If you uncouple a trailer with an engaged over-
run
brake, you could trap your hand between204
Towing a trailer
Driving and parking