2012 MERCEDES-BENZ A-CLASS HATCHBACK ECU
[x] Cancel search: ECUPage 209 of 357
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 2or 0respectively.
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 trailerDriving and parking
Page 237 of 357
Display messages
Possible causes/consequences and
M
MSolutions The red
!indicator lamp flashes and the yellow !warning
lamp is lit.
The electric parking brake is malfunctioning.
To release:
X Switch off the ignition and turn it back on.
X Release the electric parking brake manually.
To apply:
X Switch off the ignition and turn it back on.
X Apply the electric parking brake manually.
If the red !indicator lamp continues to flash:
X Do not drive on.
X Secure the vehicle against rolling away (Y page 325).
X Vehicles with manual transmission: engage first gear.
X Vehicles with automatic transmission: shift the transmission
to P.
X Turn the front wheels towards the kerb.
X Consult a qualified specialist workshop. The yellow
!warning lamp lights up. The red !indicator
lamp flashes for about ten seconds after the electric parking brake
has been applied or released. It then goes out or remains lit.
The electric parking brake is malfunctioning.
X Switch off the ignition and turn it back on.
X Apply the electric parking brake.
If it is not possible to apply the electric parking brake:
X Vehicles with manual transmission: engage first gear.
X Vehicles with automatic transmission: shift the transmission
to P.
X Visit a qualified specialist workshop.
If it is not possible to release the electric parking brake:
X Vehicles with manual transmission (automatic emergency
release): insert the seat belt in the belt buckle and accelerate
slightly more when pulling away.
X Vehicles with automatic transmission: release the electric
parking brake automatically (Y page 163).
If the electric parking brake still cannot be released:
X Consult a qualified specialist workshop. 234
Display
messagesOn-board computer and displays
Page 239 of 357
Display messages
Possible causes/consequences and
M
MSolutions J
Brake immediately Brake immediately Vehicles with manual transmission: a malfunction has occurred
while the HOLD function was activated.
A tone may also sound at regular intervals. If you attempt to lock the vehicle, the tone becomes louder.
You cannot start the engine.
X Paying attention to the traffic situation, immediately depress the
brake pedal firmly and hold until the display message disap-
pears.
X Secure the vehicle against rolling away (Y page 162).
You can restart the engine. J
Check brake fluid Check brake fluid
level level There is insufficient brake fluid in the brake fluid reservoir.
In addition, the red Jwarning lamp lights up in the instrument
cluster and a warning tone sounds.
G WARNING
The braking efficiency may be impaired.
There is a risk of an accident. X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 162).
X Consult a qualified specialist workshop.
X Do not top up the brake fluid. This does not correct the fault. #
Check brake pad Check brake pad
wear wear The brake pads/linings have reached their wear limit.
X Visit a qualified specialist workshop. PRE-SAFE
PRE-SAFE
inoperative See inoperative See
Owner's Manual Owner's Manual
Important functions of PRE-SAFE
®
have failed. All other occupant
safety systems, e.g. airbags, remain available.
X Visit a qualified specialist workshop immediately. 236
Display
messagesOn-board computer and displays
Page 240 of 357
Display messages
Possible causes/consequences and
M
MSolutions PRE-SAFE
PRE-SAFE
Functions cur‐ Functions cur‐
rently rently
limited
limited See
See
Owner's Manual
Owner's Manual Adaptive Brake Assist is temporarily inoperative. Possible causes:
R the radar sensor cover in the radiator trim is dirty.
R the 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 sta-
tions or other sources of electromagnetic radiation.
R AMG vehicles: ESP ®
is deactivated.
R the system is outside the operating temperature range.
R the on-board voltage is too low.
Once the causes listed above no longer apply, the display message
goes out.
Adaptive Brake Assist is operational again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 162).
X Clean the radar sensor cover in the radiator grille (Y page 294).
X Restart the engine.
X AMG vehicles: reactivate ESP ®
(Y page 66). PRE-SAFE PRE-SAFE
Functions limited Functions limited
See Owner's Manual See Owner's Manual Adaptive Brake Assist is faulty. The distance warning signal may
also have failed.
X Visit a qualified specialist workshop. ü If the symbol appears in the multifunction display, a seat belt
tongue has been inserted into a rear seat belt buckle.
Further information on the status indicator for the rear seat belts
(Y page 49). ý If the symbol appears in the multifunction display, a seat belt
tongue has not been inserted in a rear seat belt buckle.
G WARNING
A seat belt which is not worn correctly, or which has not been
engaged in the seat belt buckle correctly, cannot provide the
intended level of protection.
This poses an increased risk of injury.
X If necessary, ask the occupants in the rear to fasten their seat
belts (Y page 47).
Further information on the status indicator for the rear seat belts
(Y page 49). Display
messages
237On-board computer and displays Z
Page 247 of 357
Display messages
Possible causes/consequences and
M
MSolutions ?
Coolant Stop vehi‐ Coolant Stop vehi‐
cle Switch engine cle Switch engine
off off The coolant is too hot.
A warning tone also sounds.
G WARNING
Never drive with an overheated engine. Driving when your engine is overheated can cause some fluids which may have leaked into
the engine compartment to catch fire.
Steam from an overheated engine can cause serious burns, which
can occur just by opening the bonnet.
There is a risk of injury.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away (Y page 162).
X Wait until the engine has cooled down.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X Do not start the engine again until the display message goes out
and the coolant temperature is below 120 †. The engine may
otherwise be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately.
Under normal operating conditions and with the specified coolant level, the coolant temperature may rise to 120 †. # The battery is not being charged.
A warning tone also sounds.
Possible causes:
R faulty alternator
R torn poly-V-belt
R a malfunction in the electronics
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Open the bonnet.
X Check whether the poly-V-belt is torn.
If the poly-V-belt is torn:
! Do not continue driving. The engine could otherwise overheat.
X Consult a qualified specialist workshop.
If the poly-V-belt is OK: X Visit a qualified specialist workshop immediately. 244
Display
messagesOn-board computer and displays
Page 250 of 357
Display messages
Possible causes/consequences and
M
MSolutions Vehicles with Becker
®
MAP PILOT: if the Becker ®
MAP PILOT is not
connected, the radar sensor system is deactivated automatically.
Blind Spot Assist is not available.
X Connect the Becker ®
MAP PILOT; see the separate operating
instructions. Lane Keeping
Lane Keeping
Assist currently Assist currently
unavailable See unavailable See
Owner's Manual Owner's Manual Lane Keeping Assist is deactivated and temporarily inoperative.
Possible causes:
R the windscreen is dirty in the camera's field of vision.
R visibility is impaired due to heavy rain, snow or fog.
R there are no lane markings for a longer period.
R the lane markings are worn, dark or covered, e.g. by dirt or snow.
Once the causes listed above no longer apply, the display message
goes out.
Lane Keeping Assist is operational again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 162).
X Clean the windscreen. Lane Keeping Lane Keeping
Assist inoperative Assist inoperative Lane Keeping Assist is faulty.
X Visit a qualified specialist workshop. Blind Spot Assist
Blind Spot Assist
currently unavail‐ currently unavail‐
able See Owner's able See Owner's
Manual Manual Blind Spot Assist is temporarily inoperative.
You have established the electrical connection between the trailer
and your vehicle.
X Press aon the steering wheel to confirm the display mes-
sage.
Blind Spot Assist is deactivated while towing a trailer. Display
messages
247On-board computer and displays Z
Page 251 of 357
Display messages
Possible causes/consequences and
M
MSolutions Blind Spot Assist is temporarily inoperative. Possible causes:
R the sensors are dirty.
R the function is impaired due to heavy rain or snow.
R the radar sensor system is outside the operating temperature
range.
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation.
The yellow 9indicator lamps also light up in the exterior mir-
rors.
Once the causes listed above no longer apply, the display message goes out.
Blind Spot Assist is operational again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 162).
X Clean the sensors (Y page 294).
X Restart the engine. Blind Spot Assist Blind Spot Assist
inoperative inoperative Blind Spot Assist is faulty.
The yellow
9indicator lamps also light up in the exterior mir-
rors.
X Visit a qualified specialist workshop. Park Park
Assist
Assist cancel‐
cancel‐
led
led The driver's door is open and the driver's seat belt has not been
fastened.
X Repeat the parking process with the seat belt fastened and the
driver's door closed. You inadvertently touched the multifunction steering wheel while
steering intervention was active.
X While steering intervention is active, make sure not to touch the
multifunction steering wheel. The vehicle has started to skid and ESP
®
has intervened.
X Use Active Parking Assist again later (Y page 186).248
Display
messagesOn-board computer and displays
Page 252 of 357
Display messages
Possible causes/consequences and
M
MSolutions Park
Park
Assist
Assist inoper‐
inoper‐
ative
ative You have just carried out a large number of turning or parking
manoeuvres.
Active Parking Assist will become available again after approx-
imately ten minutes (Y
page 186).
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Switch off and restart the engine.
If the display message continues to be displayed: X Visit a qualified specialist workshop. PARKTRONIC is faulty.
X Visit a qualified specialist workshop. DISTRONIC PLUS off DISTRONIC PLUS off DISTRONIC PLUS has been deactivated (Y
page 173). If it was
deactivated automatically, a warning tone also sounds. DISTRONIC PLUS
DISTRONIC PLUS
available again available again DISTRONIC PLUS is operational again after having been tempo-
rarily unavailable. You can now reactivate DISTRONIC PLUS
(Y
page 173). DISTRONIC DISTRONIC
PLUS
PLUScur‐
cur‐
rently
rently unavailable
unavailable
See Owner's Manual
See Owner's Manual DISTRONIC PLUS is temporarily inoperative. Possible causes:
R the function is impaired due to heavy rain or snow.
R the sensors in the radiator trim are dirty
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation.
R the system is outside the operating temperature range.
R the on-board voltage is too low.
A warning tone also sounds.
Once the causes listed above no longer apply, the display message goes out.
DISTRONIC is operational again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 162).
X Clean the sensors in the radiator trim (Y page 294).
X Restart the engine. Display
messages
249On-board computer and displays Z