2012 MERCEDES-BENZ A-CLASS HATCHBACK trailer

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/ hfor
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 Mis temporarily activated
(vehicles with automatic transmission): the automatic transmission may switch back to
the last active automatic drive program Eor
S. The automatic transmission may shift to a higher gear. This can reduce the engine'sbraking 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
203Driving 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 Check trailer
trailer hitch
hitchlock
lockdisplay 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 between
the vehicle and the trailer drawbar. This poses a risk of injury.
Do not uncouple a trailer with an engaged
overrun brake. 204
Towing a trailerDriving an
d parking

!
Do not disconnect a trailer with an
engaged overrun brake. Otherwise, your
vehicle could be damaged by the rebound- ing of the overrun brake.
! 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 Make sure that the transmission is in posi-
tion P.
X Apply the electric parking brake.
X Secure the trailer against rolling away.
X Remove the trailer cable and decouple the
trailer. Folding in 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.
X Fold the ball coupling back in if you are not
using the trailer tow hitch.
X Place the protective covering on the ball
coupling.
The release wheel is located behind the left-
hand side trim panel in the boot. 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. X
Press the ball coupling in the direction of
the arrow until it engages behind the
bumper.
Indicator lamp ?goes out and the mes-
sage in the multifunction display disap-
pears. Trailer power supply
! You can connect accessories with a
power rating of up to 240 W to the perma-
nent power supply and with a power rating of up to 180 W to the power supply that is
switched on via the ignition lock. Towing a trailer
205Driving and parking Z

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

Safety systems
Display messages
Possible causes/consequences and
M
MSolutions !÷
currently unavail‐ currently unavail‐
able See Owner's able See Owner's
Manual Manual ABS (Anti-lock Braking System), ESP
®
(Electronic Stability Pro-
gram), BAS (Brake Assist), PRE-SAFE ®
, the HOLD function, hill
start assist and ESP ®
trailer stabilisation are temporarily unavail-
able.
The adaptive brake lights and COLLISION PREVENTION ASSIST
may also have failed.
In addition, the ÷,åand! warning lamps light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
Possible causes:
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 affec-ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steer-
ing movements, at a speed above 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 inoperative See
Owner's Manual Owner's Manual ABS, ESP
®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist
and ESP ®
trailer stabilisation are unavailable due to a malfunction.
The adaptive brake lights and COLLISION PREVENTION ASSIST
may also have failed.
In addition, the J,÷,åand! warning lamps light up
in the instrument cluster.
ATTENTION ASSIST is deactivated.
G WARNING 230
Display messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions 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 affec- ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. ÷
currently unavail‐ currently unavail‐
able See Owner's able See Owner's
Manual Manual ESP
®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist and
ESP ®
trailer stabilisation are temporarily unavailable.
The adaptive brake lights and COLLISION PREVENTION ASSIST
may also have failed.
In addition, the ÷andå warning lamps light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
The self-diagnosis function, for example, may not be complete.
G WARNING
The brake system continues to function normally, but without the functions listed above.
The braking distance may thus increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steer-
ing movements, at a speed above 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. Display
messages
231On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions ÷
inoperative See inoperative See
Owner's Manual Owner's Manual ESP
®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist and
ESP ®
trailer stabilisation are not available due to a malfunction.
The adaptive brake lights and COLLISION PREVENTION ASSIST
may also have failed.
In addition, the ÷andå 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 braking distance may thus increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Drive on carefully.
X Visit a qualified specialist workshop. T!
÷
inoperative See inoperative See
Owner's Manual Owner's Manual EBD (electronic brake force distribution), ABS, ESP
®
, BAS, PRE-
SAFE ®
, the HOLD function, hill start assist and ESP ®
trailer stabi-
lisation are unavailable due to a malfunction.
The adaptive brake lights and COLLISION PREVENTION ASSIST
may also have failed.
In addition, the ÷,åand! warning lamps light up in the
instrument cluster and a warning tone sounds.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore
lock, for example, if you brake hard.
The steerability and braking characteristics may be severely affec-ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. 232
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions 6
Rear centre mal‐ Rear centre mal‐
function Consult function Consult
workshop workshop SRS has malfunctioned at the rear centre. The
6warning lamp
also lights up in the instrument cluster.
G WARNING
The airbags or belt tensioners may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
This poses an increased risk of injury. X Visit a qualified specialist workshop. 6
Left Left
windowbag
windowbag mal‐
mal‐
function Consult
function Consult
workshop workshop orRight
Right
windowbag malfunc‐
windowbag malfunc‐
tion Consult work‐ tion Consult work‐
shop shop There is a malfunction in the left-hand and/or right-hand window-
bag. The 6warning lamp also lights up in the instrument clus-
ter.
G WARNING
The left or right windowbag may either be triggered unintentionally or, in the event of an accident, may not be triggered.
This poses an increased risk of injury.
X Visit a qualified specialist workshop. Lights
i Display messages about LEDs:
This display message will only appear if all the LEDs have failed. Display messages
Possible causes/consequences and
M MSolutions b
Left cornering Left cornering
light light
orRight cor‐
Right cor‐
nering light
nering light The left or right-hand cornering light is faulty.
X Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Left dipped beam Left dipped beam
or
Right dipped Right dipped
beam
beam The left or right-hand dipped-beam headlamp is faulty.
X Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Trailer left tail Trailer left tail
lamp lampor
Trailer
Trailer
right tail lamp
right tail lamp The left or right-hand trailer tail lamp is faulty.
X Check whether you are permitted to replace the bulb yourself.
or X Visit a qualified specialist workshop. Display
messages
239On-board computer and displays Z