brake MERCEDES-BENZ B-CLASS 2012 Workshop Manual

i
The last speed
stored remains stored until
you switch off the engine.
DISTRONIC PLUS is automatically
deactivated if:
R you engage the electric parking brake or if
the vehicle is automatically secured with
the electric parking brake
R you are driving slower than 7 mph
(10km/h) and there is no vehicle in front,
or if the vehicle in front is no longer
detected
R ESP ®
intervenes or you deactivate ESP ®
R the transmission is in the P, R or N position
R you pull the cruise control lever towards
you in order to pull away and the front-
passenger door or one of the rear doors is
open
R the vehicle has skidded
If DISTRONIC PLUS is deactivated, you will
hear a warning tone. You will see the
DISTRONIC PLUS Off message in the
multifunction display for approximately five
seconds.
In the Assistance menu (Y page 194) of the
on-board computer, you can select the
distance display. Distance display when DISTRONIC PLUS is
deactivated
:
Vehicle in front, if detected
; Distance indicator, current distance to
the vehicle in front
= Specified minimum distance to the
vehicle in front; adjustable
? Own vehicle X
Select the Distance Display function
using the on-board computer
(Y page 194).
Tips for driving with DISTRONIC PLUS General notes
The following
contains

descriptions of certain
road and traffic conditions in which you must
be particularly attentive. In such situations,
brake if necessary. DISTRONIC PLUS is then
deactivated.
Cornering, going into and coming out of a
bend The ability of DISTRONIC PLUS to detect
vehicles when cornering is limited. Your
vehicle may brake unexpectedly or late.
Vehicles traveling on a different line
DISTRONIC PLUS may not detect vehicles
traveling on a different line. The distance to
the vehicle in front will be too short.166
Driving systems
Driving and parking
ProCarManuals.com

Other vehicles changing lanes
DISTRONIC PLUS has not detected the
vehicle cutting in yet. The distance to this
vehicle will be too short.
Narrow vehicles
DISTRONIC PLUS has not yet detected the
vehicle in front on the edge of the road,
because of its narrow width. The distance to
the vehicle in front will be too short.
Obstructions and stationary vehicles
DISTRONIC PLUS does not brake for
obstacles or stationary vehicles. If, for example, the detected vehicle turns a corner
and reveals
an
obstacle or stationary vehicle,
DISTRONIC PLUS will not brake for these.
Crossing vehicles DISTRONIC PLUS may detect vehicles that
are crossing
your

lane by mistake. Activating
DISTRONIC PLUS at traffic lights with
crossing traffic, for example, could cause
your vehicle to pull away unintentionally. HOLD function
Important safety notes G
WARNING
When leaving the vehicle, it can still roll away
despite being braked

by the HOLD function if:
R there is a malfunction in the system or in
the voltage supply.
R the HOLD function has been deactivated by
pressing the accelerator pedal or the brake
pedal, e.g. by a vehicle occupant.
R the electrical system in the engine
compartment, the battery or the fuses have
been tampered with.
R the battery is disconnected
There is a risk of an accident.
If you wish to exit the vehicle, always turn off
the HOLD function and secure the vehicle
against rolling away. Driving systems
167
Driving and parking Z
ProCarManuals.com

!
If DISTRONIC PLUS
or the HOLD function
is activated, the vehicle brakes
automatically in certain situations. To
prevent damage to the vehicle, deactivate
DISTRONIC PLUS and the HOLD function in
the following or other similar situations:
R when towing the vehicle
R in the car wash
Deactivate the HOLD function (Y page 168).
General notes The HOLD function can assist the driver in the
following situations:
R
when pulling away, especially on steep
slopes
R when maneuvering on steep slopes
R when waiting in traffic
The vehicle is kept stationary without the
driver having to depress the brake pedal.
The braking effect

is canceled and the HOLD
function deactivated when you depress the
accelerator pedal to pull away.
Activation conditions You can activate the HOLD function if:
R
the vehicle is stationary
R the engine is running or if it has been
automatically switched off by the ECO
start/stop function
R the driver's
door

is closed or your seat belt
is fastened
R the electric parking brake is released
R the transmission position D, R or N is
engaged while driving a vehicle with an
automatic transmission
R DISTRONIC PLUS is deactivated Activating the HOLD function X
Make sure that the activation conditions
are met.
X Depress the brake pedal.
X Quickly depress the brake pedal further
until : appears in the multifunction
display.
The HOLD function is activated. You can
release the brake pedal.
i If depressing the brake pedal the first
time does not activate the HOLD function,
wait briefly and then try again.
Deactivating the HOLD function The HOLD function is deactivated
automatically if:
R
you accelerate. On

vehicles with automatic
transmission: only when the transmission
is in position D or R.
R the transmission is in position P on vehicles
with automatic transmission.
R you depress the brake pedal again with a
certain amount of pressure until :
disappears from the multifunction display.
R you secure the vehicle using the electric
parking brake.
R you activate DISTRONIC PLUS.
i After a time, the electric parking brake
secures the vehicle and relieves the service
brake. 168
Driving systems
Driving and parking
ProCarManuals.com

The electronic parking brake secures the
vehicle automatically if the HOLD function is
activated 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
automatically switched off by the ECO
start/stop function.
R a system malfunction occurs.
R the power supply is not sufficient.
If a malfunction
occurs, then the transmission
may be shifted into position P automatically.PARKTRONIC
Important safety notes PARKTRONIC is only an aid. It is not a
replacement for your attention to your
immediate surroundings. You are always
responsible for safe maneuvering, parking
and exiting a parking space. When
maneuvering, parking or pulling out of a
parking space, make sure that there are no
persons, animals or objects in the area in
which you are maneuvering.
!
When parking, pay

particular attention to
objects above or below the sensors, such
as flower pots or trailer drawbars.
PARKTRONIC 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 other
objects that absorb ultrasonic waves.
Ultrasonic sources such as an automatic
car wash, the compressed-air brakes on a
truck or a pneumatic drill could cause
PARKTRONIC 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 when
you:
R
switch on the ignition
R shift the transmission

to position D, R or N
R release the electric parking brake
PARKTRONIC is deactivated at speeds above
11 mph (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 objects into
consideration that are:
R
below the detection range, e.g. people,
animals or objects
R above the detection range, e.g.
overhanging loads, truck overhangs or
loading ramps. :
Sensors in the front bumper, left-hand
side (example) Side view Driving systems
169
Driving and parking Z
ProCarManuals.com

Active Parking Assist will only detect parking
spaces:
R
that are parallel to the direction of travel
R that are at least 59 in (1.5 m) wide
R that are at least 51 in (1.3 m) longer than
your vehicle
A parking space is displayed while you are
driving past it, and until you are
approximately 50 ft (15 m) away from it.
Parking G
WARNING
Active Parking Assist merely aids you by
intervening actively in the steering. If you do
not brake there is a risk of an accident.
Always apply the brakes yourself when
maneuvering and parking.
i When PARKTRONIC detects obstacles,
Active Parking Assist brakes automatically
during the parking process. You are
responsible for braking in good time.
Active Parking Assist does not support you
with parking spaces parallel to the direction
of travel if:
R the parking space is on a curb
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
obstacle which is not clearly defined such
as a tree or a trailer
X Stop the vehicle when the parking space
symbol shows the
desired parking space in
the instrument cluster.
X Shift the transmission to 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
message appears in the multifunction
display.
X Let go of the multifunction steering wheel.
X Back up the vehicle, being ready to brake
at all times. Do not exceed a maximum
speed of approximately 5 mph (10 km/h )
when

backing up. Otherwise Active Parking
Assist will be canceled.
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.
Maneuvering may be required in tight
parking spaces.
The Park Assist Active Select D
Observe Surroundings

message appears in
the multifunction display.
X Shift the transmission to position D 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
waiting 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.174
Driving systems
Driving and parking
ProCarManuals.com

The Park Assist Active Select R
Observe Surroundings

message appears in
the multifunction display.
X Further transmission shifts may be
necessary.
As soon as the parking procedure is
complete, the Park Assist Finished
message appears in the multifunction
display.
Active Parking Assist is then deactivated.
PARKTRONIC is still available.
X Maneuver if necessary.
X Always observe the warning messages
displayed by PARKTRONIC (
Y page 170).
Parking tips:
R The way your vehicle is positioned in the
parking space after parking is dependent
on various factors. These include the
position 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 curb. If necessary, you should
cancel the parking procedure with Active
Parking Assist.
R You can also engage forward gear
prematurely. 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 canceled. A
sensible parking position can no longer be
achieved from this position.
Exiting a parking space In order that Active Parking Assist can
support 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 maneuvers the
vehicle into a position at a maximum of 45° to the starting position in the parking
space.
R a maneuvering distance of at least 24 in
(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 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
message appears in the multifunction
display.
X Let go of 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
6 mph (10 km/h) when exiting a parking
space. Otherwise

Active Parking Assist will
be canceled.
X Stop when PARKTRONIC sounds the
continuous warning tone, if not before.
X Shift the transmission 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
waiting for the steering procedure to
complete before pulling away. Driving systems
175
Driving and parking Z
ProCarManuals.com

If you back up after activation, the steering
wheel is moved to the straight-ahead
position.
X Drive forwards or back up 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
completely, the steering wheel is moved to
the straight-ahead position. You hear a tone
and the Park Assist Finished message
appears in the

multifunction display. You will
then have to steer and merge into traffic on
your own. PARKTRONIC is still available.
Canceling 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 canceled at
once. The Park Assist Canceled
message appears in the multifunction
display.
or
X Press the PARKTRONIC button on the
center console (
Y

page 171).
PARKTRONIC is switched off and Active
Parking Assist is immediately canceled.
The Park Assist Canceled message
appears in the multifunction display.
Active Parking Assist is canceled
automatically if:
R you engage the electric parking brake.
R parking using Active Parking Assist is no
longer possible.
R you are driving faster than 6 mph
(10 km/h).
R a wheel

spins, 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
display shows the
Park Assist Canceled
message.
If Active
Parking

Assist is canceled, you must
steer again yourself.
If a system malfunction occurs, the vehicle is
braked to a standstill. To drive on, depress the
accelerator again. Rear view camera
Important safety notes The rear view camera is only an aid. It is not
a replacement for your attention to your
immediate surroundings. You are always
responsible for safe maneuvering and
parking.
When
maneuvering

or parking, make
sure that there are no persons, animals or
objects in the area in which you are
maneuvering.
Under the following circumstances, the rear
view camera will not function, or will function
in a limited manner:
R the tailgate is open
R in heavy rain, snow or fog
R at night or in very dark places
R if the camera is exposed to very bright light
R if the area is lit by fluorescent light or LED
lighting (the display may flicker)
R if there is a sudden change in temperature,
e.g. when driving into a heated garage in
winter
R if the camera lens is dirty or obstructed
R if the rear of your vehicle is damaged. In
this event, have the camera position and
setting checked at a qualified specialist
workshop.176
Driving systemsDriving and parking
ProCarManuals.com

At speeds above 20 mph (30 km/h) the
indicator lamp
goes
out and Blind Spot Assist
is operational.
If a vehicle is detected within the monitoring
range of Blind Spot Assist at speeds above
20 mph (30 km/h), warning lamp : on the
corresponding side lights up red. This warning
is always emitted when a vehicle enters the
blind spot monitoring range from behind or
from the side. When you overtake a vehicle,
the warning only occurs if the difference in
speed is less than 7 mph (12 km/h).
The yellow indicator lamp goes out if reverse
gear is engaged. In this event, Blind Spot
Assist is no longer active.
The brightness of the indicator/warning
lamps is adjusted automatically according to
the ambient light.
Collision warning
If a vehicle is detected in the monitoring range
of Blind Spot Assist and you switch on the
corresponding turn signal, a double warning
tone sounds. Red warning lamp : flashes. If
the turn signal remains on, vehicles detected
are indicated by the flashing of red warning
lamp :. There are no further warning tones.
Switching on Blind Spot Assist
X Make sure that the radar sensor system
(Y page 199) and Blind Spot Assist
(Y page 195)
are

activated in the on-board
computer.
X Turn the SmartKey to position 2 in the
ignition lock.
Warning lamps : in the exterior mirrors
light up red for approximately
1.5 seconds and then turn yellow.
Lane Keeping Assist General notes
Lane Keeping Assist monitors the area in
front of
your

vehicle by means of a camera at
the top of the windshield. Lane Keeping Assist
detects lane markings on the road and warns you before you leave your lane
unintentionally.
:
Lane Keeping Assist camera
If you select km on the on-board computer in
the Display Unit Speed-/Odometer:
function ( Y page 196), 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 may not always clearly
recognize lane markings.
In this case, 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 stay in lane, in particular if
warned by Lane Keeping Assist. G
WARNING
The Lane Keeping Assist warning does not
return the vehicle to the original lane. There
is a risk of an accident.
You should always steer, brake or accelerate
yourself, in particular if warned by Lane
Keeping Assist.
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
the road, traffic and weather conditions. Lane Driving systems
183
Driving and parking Z
ProCarManuals.com

Keeping Assist is merely 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 your lane.
The Lane Keeping Assist does not keep the
vehicle in the lane.
The system may be impaired or may not
function if:
R
there is poor visibility, e.g. due to
insufficient illumination of
the road, or due
to snow, rain, fog or spray
R there is glare, e.g. from oncoming traffic,
the sun or reflections (e.g. when the road
surface is wet)
R the windshield is dirty, fogged up, damaged
or covered, for instance by a sticker, in the
vicinity of the camera
R there are no, several or unclear lane
markings for a lane, e.g. in areas with road
construction work
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 strong shadows cast on the lane
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.
Switching on Lane Keeping Assist X
Switch on Active Lane Keeping Assist using
the on-board computer; to do so, select
Standard or Adaptive (Y page 195).
Symbol : appears in the multifunction
display.
If you drive at speeds above 40 mph
(60 km/h
) and lane markings are detected,
symbol : is highlighted. Lane Keeping
Assist is ready for use.
When Standard is selected, no warning
vibration occurs if:
R you switch 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
vibration occurs if:
R you switch on the turn signals. In this event,
the warnings are suppressed for a certain
period of time.
R a driving safety system intervenes, e.g.
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 lanes quickly.
R you cut the corner on a sharp bend.
In order that you are warned only when
necessary and in good time if you cross the
lane marking, the system recognizes certain
conditions 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
freeway.
R the system recognizes solid lane markings.
The warning vibration occurs later if:
R the road has narrow lanes.
R you cut the corner on a bend.184
Driving systems
Driving and parking
ProCarManuals.com

Safety systems
Display messages Possible causes/consequences and
M Solutions!÷
Currently
Unavailable See
Operator's Manual ABS (Anti-lock Braking System), ESP
®
(Electronic Stability
Program), BAS (Brake Assist), the HOLD function and hill start
assist are temporarily unavailable.
COLLISION PREVENTION ASSIST may also have failed.
In addition, the ÷, å and ! warning lamps light up in
the instrument cluster.
ATTENTION ASSIST is deactivated.
Possible causes are:
R Self-diagnosis is not yet complete.
R The on-board voltage may be insufficient.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
The steerability and braking characteristics may be severely
affected. The braking distance in an emergency braking situation
can increase.
If ESP ®
is not
operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Carefully drive a short distance on a suitable stretch of road,
making slight steering movements at a speed above 12 mph
(20 km/h).
If the display message disappears, the functions mentioned
above are available again.
If the display message continues to be displayed:
X Drive on carefully.
X Visit a qualified specialist workshop. !÷
Inoperative See
Operator's Manual ABS, ESP
®
, BAS, the HOLD function and hill start assist are
unavailable due to a malfunction.
COLLISION PREVENTION ASSIST may also have failed.
In addition, the J, ÷, å and ! warning lamps light
up in the instrument cluster.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example. Display messages
201On-board computer and displays Z
ProCarManuals.com