2012 MERCEDES-BENZ C-Class SEDAN brake sensor

:Symbol for activated PRE-SAFE®
Brake;Vehicle in front, if detected=Distance indicator, current distance to
the vehicle in front?Specified minimum distance to the
vehicle in front; adjustableAOwn vehicle
Display when DISTRONIC PLUS is
activated
XSelect the Distance Display function
using the on-board computer
( Y page 204).
You will see the stored speed for about five
seconds when you activate DISTRONIC PLUS.
After this time, you will see the following in
the multifunction display while DISTRONIC
PLUS is activated:
:DISTRONIC PLUS activated;Own vehicle=Specified minimum distance to the
vehicle in front; adjustable?Vehicle in front, if detectedDeactivating DISTRONIC PLUS
There are several ways to deactivate
DISTRONIC PLUS:
XBriefly press the cruise control lever
forwards :.
or
XBrake, unless the vehicle is stationary.
When you deactivate DISTRONIC PLUS, the
DISTRONIC PLUS Off message is shown in
the multifunction display for approximately
five seconds.
i The last speed stored remains stored until
you switch off the engine.
i DISTRONIC PLUS is not deactivated if you
depress the accelerator pedal. If you
accelerate to overtake, DISTRONIC PLUS
adjusts the vehicle's speed to the last
speed stored after you have finished
overtaking.
DISTRONIC PLUS is automatically
deactivated if:
R you apply the parking brake.
R you are driving slower than
15 mph (25 km/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 switch off the radar sensor system
( Y page 208).
R you pull the cruise control lever towards
you in order to pull away and the front-
Driving systems169Driving and parkingZ

The multifunction display shows the RACE
START active message.
RACE START is deactivated when a speed of
approximately 30 mph (Canada: 50 km/h) is
reached. 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
conditions are no longer fulfilled. The
multifunction display shows the RACE START
not possible See Operator's Manual
message.
i If RACE START is used repeatedly within
a short period of time, it is only available
again after the vehicle has been driven a
certain distance.
4MATIC (permanent four-wheel drive)
4MATIC ensures that all four wheels are
permanently driven. Together with ESP ®
, it
improves the traction of your vehicle
whenever a drive wheel spins due to
insufficient grip.
GWARNING
If a drive wheel is spinning due to insufficient
traction:
R While driving off, apply as little throttle as
possible.
R While driving, ease up on the accelerator
pedal.
R Adapt your speed and driving style to the
prevailing road conditions.
Failure to observe these guidelines could
cause the vehicle to skid.
The 4MATIC cannot prevent accidents
resulting from excessive speed.
! 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 Limited 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 tires ( M+S tires), with snow
chains if necessary.
PARKTRONIC
Important safety notes
i PARKTRONIC is only available in Canada.
GWARNING
The PARKTRONIC is a supplemental system.
It is not intended to, nor does it replace, the
need for extreme care. The responsibility
during parking and other critical maneuvers
always remains with the driver.
GWARNING
Make sure no persons or animals are in or
near the area in which you are parking/
maneuvering. Otherwise, they could be
injured.
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 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.
Driving systems175Driving and parkingZ

:Sensors in the front bumper, left-hand
side (example)
Range of the sensors
General notes
The sensors must be free of dirt, ice and
slush; otherwise they may not function
correctly. Clean the sensors regularly, taking
care not to scratch or damage them
( Y page 287).
Side view
Top view
Front sensorsCenterApproximately 40 in
(approximately 100 cm)CornersApproximately 24 in
(approximately 60 cm)
Rear sensors
CenterApproximately 48 in
(approximately 120 cm)CornersApproximately 32 in
(approximately 80 cm)
! 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.
Minimum distance
CenterApproximately 8 in
(approximately 20 cm)CornersApproximately 6 in
(approximately 15 cm)
If there is an obstacle within this range, the
relevant warning displays light up and a
warning tone sounds. If the distance falls
below the minimum, the distance may no
longer be shown.
176Driving systemsDriving and parking

Active Driving Assistance package
General notes
The Active Driving Assistance package
consists of DISTRONIC PLUS ( Y page 161),
Active Blind Spot Assist ( Y page 187) and
Active Lane Keeping Assist ( Y page 190).
Active Blind Spot Assist
Important safety notes
Active Blind Spot Assist uses a radar sensor
system to monitor the side areas of your
vehicle which are in back of the driver. A
warning display in the exterior mirrors draws
your attention to vehicles detected in the
monitored area. If you then switch on the
corresponding turn signal to change lane, you
will also receive an optical and audible
collision warning. If a risk of lateral collision
is detected, corrective braking may help you
avoid a collision. To support the course-
correcting brake application, Active Blind
Spot Assist also uses the forward-facing radar
sensor system. Active Blind Spot Assist
supports you from speeds of approximately
20 mph (30 km/h).
GWARNING
Active Blind Spot Assist is only an aid, and
may detect vehicles/obstacles incorrectly or
not at all.
The system may be impaired or may not
function if:
R there is poor visibility, e.g. due to snow,
rain, fog or spray.
R the rear and/or front sensors are dirty.
Active Blind Spot Assist may not detect
narrow vehicles, such as motorcycles or
bicycles, or may only detect them too late. It
cannot detect vehicles that are overtaken at
a small distance and then enter the blind spot
area.
Active Blind Spot Assist cannot detect road
and traffic conditions. It is not a substitute for
attentive driving. You are responsible for the
vehicle's speed, braking in good time, and
steering correctly. Always adapt your driving
style to suit the prevailing road and weather
conditions. Always pay attention to traffic
conditions and your surroundings. Otherwise,
you may fail to recognize dangers in time,
cause an accident and injure yourself and
others.
i USA only:
This device has been approved by the FCC
as a “Vehicular Radar System”. The radar
sensor is intended for use in an automotive
radar system only. Removal, tampering, or
altering of the device will void any
warranties, and is not permitted by the
FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this
device could void the user’s authority to
operate the equipment.
For Active Blind Spot Assist to assist you
when driving, the radar sensor system must
be activated ( Y page 208) and operational.
Monitoring area
Active Blind Spot Assist monitors the area
shown in the figure up to 10 ft (3 m) behind
and immediately adjacent to your vehicle. For
this purpose, Active Blind Spot Assist uses
radar sensors in the rear bumper.Driving systems187Driving and parkingZ

GWARNING
Active Blind Spot Assist monitors certain
areas in the immediate vicinity of your vehicle.
Vehicles that approach and drive past at high
speeds are not detected. No visual nor
audible warnings are emitted and the system
does not brake the vehicle to correct your
course.
If the lanes are very wide, it may not be
possible to monitor the complete width of the
neighboring lane. For this reason, vehicles in
the next lane may not be detected, especially
if they are driving in a staggered formation.
This may be the case if vehicles are driving at
that edge of their lane which is furthest away
from your vehicle.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
If the lanes are narrow, vehicles driving in the
lane beyond the lane next to your vehicle may
be indicated, especially if the vehicles are not
driving in the middle of their lane. This may
be the case if there are vehicles driving at the
inner edge of their lanes.
Due to the nature of the system:
R warnings may be issued in error when
driving close to crash barriers or similar
solid lane borders.
R warnings may be interrupted when driving
alongside long vehicles, such as trucks, for
a prolonged time.
Two Active Blind Spot Assist radar sensors
are integrated into the front and rear bumpers
respectively. An additional radar sensor is
located behind the cover in the radiator grill.
Make sure that the sensor areas on the
bumpers and the sensor cover in the radiator
grill are free of dirt, ice and slush. The rear
sensors must not be covered, for example by
cycle racks or overhanging cargo. Following
a severe impact or in the event of damage to
the bumpers, have the function of the radar
sensors checked at a qualified specialist
workshop. Blind Spot Assist may otherwise
not work properly.
Indicator and warning display:Yellow indicator lamp/red warning lamp
When Active Blind Spot Assist is activated,
indicator lamp : lights up yellow in the
exterior mirrors up to a vehicle speed of
20 mph (30 km/h). When the vehicle speed
exceeds 20 mph (30 km/h), the indicator
lamp goes out and Active Blind Spot Assist is
ready for use.
When your speed exceeds approximately
20 mph (30 km/h), warning lamp : lights up
red on the corresponding side whenever a
vehicle is detected in the blind spot
monitoring range. This warning is always
given when a vehicle enters the blind spot
monitoring range from behind or from the
side. When you are passing another vehicle,
the warning is emitted only 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, Active Blind
Spot Assist is no longer active.
The brightness of the indicator/warning
lamps is adjusted automatically according to
the ambient light.
GWARNING
Active Blind Spot Assist is not active at speeds
lower than 20 mph (30 km/h). The indicator
lamps in the exterior mirrors are yellow.
Vehicles in the monitoring range are then not
indicated.
188Driving systemsDriving and parking

Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
Visual and audible collision warnings
If you switch on the appropriate turn signals
and a vehicle is detected in the side
monitoring range, you will receive a visual and
acoustic collision warning. You will hear a
double warning tone and 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.
Course-correcting brake application
If Active Blind Spot Assist detects a risk of a
lateral collision in the monitoring range, a
course-correcting brake application is carried
out. This is meant to assist you in avoiding a
collision.
The course-correcting brake application is
available in the range between 20 mph
(30 km/h) and 120 mph (200 km/h).
If a course-correcting brake application
occurs, red warning lamp : flashes in the
exterior mirror and the following is shown in
the multifunction display, for example:GWARNING
Active Blind Spot Assist is only an aid
designed to assist driving. It is not a substitute
for attentive driving. In some cases, the
course-correcting brake application is not
sufficient to avoid a collision. In such a case,
you must steer, brake or accelerate.
In very rare cases, the system may
erroneously detect a danger of collision in the
area of crash barriers or similar lane borders
and apply the brakes. Active Blind Spot Assist
does not detect all traffic situations and road
users. Always make sure that there is
sufficient distance on the side for other traffic
or obstacles. An inappropriate brake
application may be interrupted at any time if
you steer slightly in the opposite direction or
accelerate.
You are responsible for driving at appropriate
speeds, braking in good time, and steering
correctly. Always adapt your driving style to
suit the prevailing road and weather
conditions. Always pay attention to traffic
conditions and your surroundings. Otherwise,
you may fail to recognize dangers in time,
cause an accident and injure yourself and
others.
There will be either no or only a weak course-
correcting brake application if:
R there are vehicles or obstacles, e.g. crash
barriers, located on both sides of your
vehicle.
R a vehicle approaches you too closely at the
side.
R you have adopted a sporty driving style with
high cornering speeds.
R you clearly brake or accelerate.
R a driving safety system intervenes, e.g.
ESP ®
or PRE-SAFE ®
Brake.
R ESP ®
is switched off.
R a loss of tire pressure or a defective tire is
detected.
Switching on Active Blind Spot AssistXMake sure that the radar sensor system
( Y page 208) and Active Blind Spot Assist
( Y page 205) are activated in the on-board
computer.XTurn the SmartKey to position 2 in the
ignition lock.
Warning lamps : light up red in the
exterior mirrors for approximately 1.5
seconds and then turn yellow.Driving systems189Driving and parkingZ

Deactivating delayed switch-off of the
exterior lighting temporarily:XBefore leaving the vehicle, turn the
SmartKey to position 0 in the ignition lock.XTurn the SmartKey to position 2 in the
ignition lock and back to position 0.
The exterior lighting delayed switch-off is
deactivated.
Delayed switch-off of the exterior lighting is
reactivated the next time you start the
engine.
Activating/deactivating the interior
lighting delayed switch-off
If you activate the Light. delay function,
the interior lighting remains on for 20
seconds after you remove the SmartKey from
the ignition lock.
XPress the = or ; button on the
steering wheel to select the Settings
menu.XPress the : or 9 button to select the
Lights submenu.XPress the a button to confirm.XPress the : or 9 button to select the
Light. Delay function.
When the Light. Delay function is
activated, the vehicle interior is displayed
in red in the multifunction display.XPress the a button to save the setting.
Vehicle
Activating/deactivating the automatic
door locking feature
If you select the Auto. Door Locks
function, the vehicle is centrally locked above
a speed of around 9 mph (15 km/h).
i For further information on the automatic
locking feature, see ( Y page 78).
XPress the = or ; button on the
steering wheel to select the Settings
menu.XPress the : or 9 button to select the
Vehicle submenu.XPress the a button to confirm.XPress the : or 9 button to select the
Auto. Door Locks function.
When the Auto. Door Locks function is
activated, the vehicle doors are displayed
in red in the multifunction display.XPress the a button to save the setting.
Activating/deactivating the acoustic
locking verification signal
If you activate the Acoustic Lock function,
an audible signal sounds depending on the
vehicle's date of manufacture:
R when locking
or
R once when unlocking and three times when
locking
XPress the = or ; button on the
steering wheel to select the Settings
menu.XPress the : or 9 button to select the
Vehicle submenu.XPress the a button to confirm.XPress the : or 9 button to select the
Acoustic Lock function.
If the Acoustic Lock function is activated,
the & symbol in the multifunction
display lights up red.XPress the a button to save the setting.
Activating/deactivating the radar sensor
system
The following systems are switched off when
the radar sensor system is deactivated:
R DISTRONIC PLUS ( Y page 161)
R BAS PLUS ( Y page 60)
R PRE-SAFE ®
Brake ( Y page 65)
208Menus and submenusOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsG
Tele Aid
InoperativeUSA only: one or more of the main functions in the mbrace system
are malfunctioning.
Canada only: one or more of the main functions of the TELEAID
system are malfunctioning.XUSA only: have the mbrace system checked at a qualified
specialist workshop.XCanada only: have the TELEAID system checked at a qualified
specialist workshop.PRE-SAFE
Function Currently
Limited See Oper.
ManualGRisk of accident
PRE-SAFE ®
Brake is temporarily inoperative if:
R the DISTRONIC PLUS cover in the radiator grill is dirty.
R the sensors in the bumpers are dirty.
R its function is impaired due to heavy rain or snow.
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio
stations or other sources of electromagnetic radiation.
R you switch off ESP ®
(AMG vehicles only).
R the system is outside the operating temperature range.
R the on-board voltage is too low.
PRE-SAFE ®
Brake is operational again and the display message
disappears if:
R the dirt (e.g. slush) drops away while the vehicle is in motion.
R the system detects that the sensors are fully available again.
R you switch ESP ®
on again (AMG vehicles only).
R the system is within the operating temperature range.
If the display message continues to be displayed:
XClean the DISTRONIC PLUS cover in the radiator grill
( Y page 287).XClean the bumpers ( Y page 287).XRestart the engine.XWait until the battery is sufficiently charged.PRE-SAFE
Functions Limited
See Operator's
ManualGRisk of accident
PRE-SAFE ®
Brake is defective. BAS PLUS or the distance warning
signal may also have failed.
XVisit a qualified specialist workshop.218Display messagesOn-board computer and displays