2012 MERCEDES-BENZ C-Class SEDAN brake light

Active Lane Keeping Assist does not detect
traffic situations or road users. An
inappropriate brake application may be
interrupted at any time if you:
R steer slightly in the opposite direction.
R use a turn signal.
R clearly brake or accelerate.
A lane-correcting brake application is
interrupted automatically if:
R a driving safety system intervenes, e.g.
ESP ®
, PRE-SAFE ®
Brake or Active Blind
Spot Assist.
R lane markings can no longer be recognized.
Switching on Active Lane Keeping AssistXSwitch on Active Lane Keeping Assist using
the on-board computer ( Y page 205).
Symbol : appears in the multifunction
display.
If your speed exceeds 40 mph (60 km/h)
and lane markings are detected,
symbol : is shown in green. Active Lane
Keeping Assist is ready for use.192Driving systemsDriving and parking

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

Safety systemsDisplay messagesPossible causes/consequences and M Solutions!÷
Currently
Unavailable See
Operator's ManualGRisk of accident
ABS (Anti-lock Braking System), ESP ®
(Electronic Stability
Program), BAS (Brake Assist), the HOLD function and hill start
assist are temporarily unavailable.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
In addition, the ÷, å and ! warning lamps light up in
the instrument cluster.
The self-diagnosis function might not be complete, for example.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
XCarefully drive a suitable distance 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:
XDrive on carefully.XVisit a qualified specialist workshop.GRisk of accident
ABS, ESP ®
, BAS, the HOLD function and hill start assist are
temporarily unavailable.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
In addition, the ÷, å and ! warning lamps light up in
the instrument cluster.
For example, the on-board voltage may be insufficient.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
XDrive on carefully.
If the display message disappears, the functions mentioned
above are available again.
If the display message continues to be displayed:
XDrive on carefully.XVisit a qualified specialist workshop.214Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M Solutions!÷
Inoperative See
Operator's ManualGRisk of accident
ABS, ESP ®
, BAS, the HOLD function and hill start assist are
unavailable due to a malfunction.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
The $ (USA only)/ J (Canada only), ÷, å
and ! warning lamps in the instrument cluster also light up.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
ATTENTION ASSIST is deactivated.
XDrive on carefully.XVisit a qualified specialist workshop immediately.÷
Currently
Unavailable See
Operator's ManualGRisk of accident
ESP ®
, BAS, the HOLD function and hill start assist are temporarily
unavailable.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
In addition, the ÷ and å warning lamps light up in the
instrument cluster.
The self-diagnosis function might not be complete, for example.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above.
XCarefully drive a suitable distance 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:
XDrive on carefully.XVisit a qualified specialist workshop.Display messages215On-board computer and displaysZ

Display messagesPossible causes/consequences and M Solutions÷
Inoperative See
Operator's ManualGRisk of accident
ESP ®
, BAS, the HOLD function and hill start assist are unavailable
due to a malfunction.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
In addition, the ÷ and å warning lamps light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above.
XDrive on carefully.XVisit a qualified specialist workshop.T !
÷
Inoperative See
Operator's ManualGRisk of accident
EBD (electronic brake force distribution), ABS, ESP ®
, BAS, the
HOLD function and hill start assist are unavailable due to a
malfunction.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
In addition, the ÷, å and ! warning lamps light up in
the instrument cluster and a warning tone sounds.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
XDrive on carefully.XVisit a qualified specialist workshop immediately.#
Check Brake Pad
WearThe brake pads/linings have reached their wear limit.XVisit a qualified specialist workshop.$ (USA
only) J (Canada
only)
Release Parking
BrakeYou are driving with the parking brake applied. A warning tone also
sounds.XRelease the parking brake.216Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M Solutions$ (USA
only) J (Canada
only)
Brake ImmediatelyA malfunction has occurred while the HOLD function or
DISTRONIC PLUS is active.
A tone may also sound at regular intervals. The tone becomes
louder if you attempt to lock the vehicle.
You cannot start the engine.XPaying attention to the traffic situation, immediately depress the
brake pedal firmly and hold until the display message
disappears.XPrevent the vehicle from rolling away before you leave it
( Y page 294).
You can restart the engine.$ (USA
only) J (Canada
only)
Check Brake Fluid
LevelGRisk of accident
There is not enough brake fluid in the brake fluid reservoir.
Additionally, the red $ (USA only)/ J (Canada only)
warning lamp lights up in the instrument cluster and a warning
tone sounds.
XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.XEngage the parking brake.XConsult a qualified specialist workshop.XDo not add brake fluid. This will not rectify the malfunction.GWARNING
Driving with the message Check Brake Fluid Level displayed can result in an accident. Have
your brake system checked immediately.
Do not add brake fluid before checking the brake system. Overfilling the brake fluid reservoir can
result in spilling brake fluid on hot engine parts and the brake fluid catching fire. You can be
seriously burned.
Display messages217On-board computer and displaysZ

Display messagesPossible causes/consequences and M SolutionsFront Passenger
Airbag Enabled
See Operator's
ManualThe front-passenger air bag is enabled during the journey, even
though:
R a child, a small adult or an object weighing less than the
system's weight threshold is located on the front-passenger
seat.
R the front-passenger seat is unoccupied.
The system may detect objects or forces applying additional
weight on the seat.XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.XEngage the parking brake.XSwitch off the ignition.XOpen the front-passenger door.XRemove the child and the child restraint system from the front-
passenger seat.XIf necessary, secure the child in a child restraint system on a
suitable rear seat.XMake sure that there are no objects on the seat adding to the
weight.
The system may otherwise detect the additional weight and
interpret the seat occupant's weight as greater than it actually
is.XKeep the seat unoccupied, close the front-passenger door and
switch on the ignition.
Observe the 45(Y page 42) indicator lamp and the
multifunction display and check the following:
Seat unoccupied and ignition switched on:
R the 45 indicator lamp must light up and remain lit. When
the indicator lamp is on, OCS ( Y page 42) has deactivated the
front-passenger air bag.
R the Front Passenger Airbag Enabled See Operator's
Manual or Front Passenger Airbag Disabl'd See
Operator's Manual display messages must not appear in the
multifunction display. Wait for a period of at least 60 seconds
until the necessary system checks have been completed and to
make sure that the display messages do not appear in the
multifunction display.
If these conditions are fulfilled, the front-passenger seat can be
occupied again. Whether the 45 indicator lamp remains lit
or goes out depends on how OCS classifies the occupant.
If the conditions are not fulfilled, the system is not operating
correctly.
220Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsXVisit a qualified specialist workshop immediately.GWARNING
If the 45 indicator lamp remains off even after performing the above corrective steps, do
not have any children 12 years old and under and other small individuals use the front-passenger
seat until the system has been repaired.
Display messagesPossible causes/consequences and M SolutionsFront Passenger
Airbag Disabl'd
See Operator's
ManualThe front-passenger air bag is deactivated during the journey even
though an adult or a person larger than a certain size is occupying
the front-passenger seat. If additional forces are applied to the
seat, the system may interpret the occupant's weight as lower
than it actually is.XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.XEngage the parking brake.XSwitch off the ignition.XHave the occupant get out of the vehicle.XKeep the seat unoccupied, close the front-passenger door and
switch on the ignition.
Observe the 45(Y page 42) indicator lamp and the
multifunction display and check the following:
Seat unoccupied and ignition switched on:
R the 45 indicator lamp must light up and remain lit. When
the indicator lamp is on, OCS ( Y page 42) has deactivated the
front-passenger air bag.
R the Front Passenger Airbag Enabled See Operator's
Manual or Front Passenger Airbag Disabled See
Operator's Manual display messages must not appear in the
multifunction display. Wait for a period of at least 60 seconds
until the necessary system checks have been completed and to
make sure that the display messages do not appear in the
multifunction display.
If these conditions are fulfilled, the front-passenger seat can be
occupied again. Whether the 45 indicator lamp remains lit
or goes out depends on how OCS classifies the occupant.
If the conditions are not fulfilled, the system is not operating
correctly.
XVisit a qualified specialist workshop immediately.Display messages221On-board computer and displaysZ