ECU MERCEDES-BENZ A CLASS 2012 Workshop Manual

R
One pair of gloves
R Foldable wheel chock Flat tyre
Preparing the vehicle
Your vehicle may be equipped with:
R MOExtended
tyres (tyres with run-flat char-
acteristics) (Y page 300)
Vehicle preparation is not necessary on
vehicles with MOExtended tyres.
R a TIREFIT kit (Y page 299)
R an emergency spare wheel (only for certain
countries)
Information on changing/fitting a wheel
(Y page 325).
X Stop the vehicle as far away as possible
from

traffic on solid, non-slippery and level
ground.
X Switch on the hazard warning lamps.
X Secure the vehicle against rolling away
(Y page 162).
X If possible, bring the front wheels into the
straight-ahead position.
X Switch off the engine.
X Remove the key from the ignition lock.
X All occupants must get out of the vehicle.
Make

sure that they are not endangered as
they do so.
X Make sure that no one is near the danger
area while a wheel is being changed. Any-
one who is not directly assisting in the
wheel change should, for example, stand
behind the barrier.
X Get out of the vehicle. Pay attention to traf-
fic conditions when doing so.
X Close the driver's door.
X Place the warning triangle a suitable dis-
tance away

(Y page 298). Observe legal
requirements.
i Vehicles with MOExtended tyres are not
equipped with a TIREFIT kit at the factory.
It

is therefore recommended that you addi- tionally equip your vehicle with a TIREFIT kit
if you fit tyres that do not feature run-flat
characteristics,

e.g. winter tyres. A TIREFIT
kit can be obtained from a qualified spe-
cialist workshop. MOExtended tyres (tyres with run-flat
characteristics)
General notes With MOExtended tyres (tyres with run-flat
characteristics), you can continue to drive
your vehicle even if there is a total loss of
pressure in one or more tyres. The affected
tyre must not show any clearly visible dam-
age.
You can recognise MOExtended tyres by the
MOExtended marking which appears on the
tyre

wall. You will find this marking next to the
tyre size designation, the load-bearing capa-
city and the speed index.
MOExtended tyres may only be used in con-
junction with an active tyre pressure loss
warning system.
If the pressure loss warning message
appears in the multifunction display:
R Observe the instructions in the display
messages ( Y page 251).
R Check the tyre for damage.
R If driving on, observe the following notes.
The maximum driving distance is approx-
imately 80 km when the vehicle is partially
laden and approximately 30 km when the
vehicle is fully laden.
In addition to the vehicle load, the driving dis-
tance possible depends upon:
R speed
R road condition
R outside temperature
The driving distance possible in run-flat mode
may be reduced by extreme driving condi-
tions/manoeuvres, or it can be increased
through a moderate style of driving. 300
Flat tyre
Breakdown assistance

sive gases of a battery. There is a risk of an
explosion.
Before
handling the battery, touch the vehicle
body to remove any existing electrostatic
build-up.
The highly flammable gas mixture is formed
when charging the battery or jump-starting
the vehicle.
Always make sure that neither you nor the
battery is electrostatically charged. Electro-
static charge is caused, for example, by:
R wearing synthetic clothing
R the friction of clothing on the seat
R pulling or sliding the battery over carpets
or other synthetic materials
R rubbing the battery with a cloth G
WARNING
During the charging process, a battery produ-
ces hydrogen gas. If a short circuit occurs or
sparks are created, the hydrogen gas can
ignite. There is a risk of an explosion.
R Make sure that the positive terminal of a
connected

battery does not come into con-
tact with vehicle parts.
R Never place metal objects or tools on a bat-
tery.
R It is important that you observe the descri-
bed order of the battery terminals when
connecting and disconnecting a battery.
R When jump-starting, make sure that the
battery poles with identical polarity are
connected.
R It is particularly important to observe the
described order when connecting and dis-
connecting the jump leads.
R Never connect or disconnect the battery
terminals while the engine is running. G
WARNING
Battery acid is caustic. There is a risk of injury.
Avoid
contact with the skin, eyes or clothing.
Do not inhale any battery gases. Do not lean
over the battery. Keep children away from batteries. Wash battery acid immediately with
water and seek medical attention.
H
Environmental note Batteries contain pollutants.
It

is illegal to dispose of them
with the household rubbish.
They must be collected sep-
arately and disposed of in an
environmentally responsible
recycling system. Dispose of batteries in an
environmentally responsible
manner. Take discharged
batteries to a qualified spe-
cialist workshop or to a col-
lection

point for used batter-
ies.
! Have the battery checked regularly at a
qualified specialist workshop.
Observe

the service intervals in the Service
Booklet or contact a qualified specialist
workshop for more information.
! Always have work on the battery carried
out at a qualified specialist workshop.
Should it, in exceptional circumstances, be
absolutely necessary to disconnect the bat-
tery yourself, please observe the following:
R switch off the engine and remove the
key. Check that all the indicator lamps in
the instrument cluster are off. Otherwise,
you may damage electronic components
such as the alternator, for example.
R first, disconnect the negative terminal
clamp, followed by the positive terminal
clamp. Never swap the terminal clamps.
The vehicle electronics may otherwise be
damaged.
R on vehicles with automatic transmission,
the transmission is locked in position P
after disconnecting the battery. The vehi-
cle is secured against rolling away. You
can then no longer move the vehicle. Battery (vehicle)
305
Breakdown assistance Z

The battery and the cover of the positive
terminal
clamp must be fitted securely dur-
ing operation.
Comply with safety precautions and take pro-
tective measures when handling batteries. WARNING
Fire, naked flames and smoking
are prohibited when handling the
battery. Avoid creating sparks.
Battery acid is caustic. Avoid con-
tact

with the skin, eyes or clothing.
Wear suitable protective clothing,
in particular gloves, an apron and
a face mask.
Immediately rinse acid splashes
off with clean water. Consult a doc-
tor if necessary. Wear eye protection.
Keep children away.
Observe this Owner's Manual.
For safety reasons, Mercedes-Benz recom-
mends
that you only use batteries which have
been tested and approved for your vehicle by
Mercedes-Benz. These batteries provide
increased impact protection to prevent vehi-
cle occupants from suffering acid burns
should the battery be damaged in the event
of an accident.
In order for the battery to achieve the maxi-
mum possible service life, it must always be
sufficiently charged.
Like other batteries, the vehicle battery may
discharge over time if you do not use the
vehicle. In such cases, have the battery dis-
connected at a qualified specialist workshop. You can also charge the battery with a
charger recommended by Mercedes-Benz.
For

more information, please contact a quali-
fied specialist workshop.
Have the battery charge checked more fre-
quently if you use the vehicle mainly for short
trips or if you leave it standing idle for a
lengthy period. Consult a qualified specialist
workshop if you wish to leave your vehicle
parked up for a long period of time.
i When you park the vehicle, remove the
key if you do not require any electrical con-
sumers. The vehicle will then use very little
energy, thus conserving battery power.
i If the power supply has been interrupted,
e.g. if the battery was discharged, you will
have to:
R set the clock (audio system/COMAND
Online, see the separate operating
instructions).
R reset the function for folding the exterior
mirrors in/out automatically, by folding
the mirrors out once ( Y page 99). Charging the battery
G
WARNING
During charging and jump-starting, explosive
gases
can escape from the battery. There is a
risk of an explosion.
Particularly avoid fire, naked flames, creating
sparks and smoking. Ensure there is sufficient
ventilation while charging and jump-starting.
Do not lean over a battery. G
WARNING
Battery acid is caustic. There is a risk of injury.
Avoid
contact with the skin, eyes or clothing.
Do not inhale any battery gases. Do not lean
over the battery. Keep children away from
batteries. Wash battery acid immediately with
water and seek medical attention. 306
Battery (vehicle)
Breakdown assistance

characteristics may be impaired, especially at low temperatures. Have the thawed battery
checked at a qualified specialist workshop.
Do
not use a rapid charging device to start the vehicle. If your vehicle's battery is discharged,
the engine can be jump-started from another vehicle or from a second battery using jump
leads. Observe the following points:
R The battery is not accessible in all vehicles. If the other vehicle's battery is not accessible,
jump-start the vehicle using a second battery or a jump-starting device.
R Vehicles with a petrol engine: only jump-start the vehicle when the engine and exhaust
system are cold.
R Do not start the engine if the battery is frozen. Let the battery thaw first.
R Jump-starting may only be performed from batteries with a nominal voltage of 12 V.
R Only use jump leads that have a sufficient cross-section and insulated terminal clamps.
R If the battery is fully discharged, leave the battery that is being used to jump-start connected
for a few minutes before attempting to start. This charges the empty battery a little.
R Make sure that the two vehicles do not touch.
Make sure that:
R the jump leads are not damaged.
R bare parts of the terminal clamp do not come into contact with other metal parts while the
jump leads are connected to the battery.
R the jump leads cannot come into contact with parts which can move when the engine is
running, such as the V-belt pulley or the fan.
X Secure the vehicle by applying the electric parking brake.
X Manual transmission: shift into neutral.
X Automatic transmission: shift the transmission to position P.
X Turn the key to position 0 in the ignition lock and remove it.
X Switch off all electrical consumers (e.g. radio, blower, etc.).
X Open the bonnet (Y page 285). Jump-starting
309
Breakdown assistance Z

!
Only secure the tow rope or towing bar to
the towing eyes. The vehicle may otherwise
be damaged.
! Observe the following points when towing
with a tow rope:
R secure the tow rope on the same side on
both vehicles.
R make sure that the tow rope is not longer
than legally permitted. Mark the tow rope
in the middle, e.g. with a white cloth
(30 x 30 cm). This makes other road
users aware that a vehicle is being
towed.
R only secure the tow rope to the towing
eye.
R observe the brake lamps of the towing
vehicle while driving. Always maintain a
distance so that the tow rope does not
sag.
R do not use steel cables or chains to tow
your vehicle. You could otherwise dam-
age the vehicle.
! Do not use the towing eyes for recovery
purposes as this could damage the vehicle.
If in doubt, recover the vehicle with a crane.
! Pull away smoothly when towing away or
tow-starting a vehicle. If the tractive power
is too high, the vehicles could be damaged.
! You may tow the vehicle for a maximum
of 50km. A towing speed of 50 km/h must
not be exceeded.
For towing distances over 50 km, the front
axle or the entire vehicle must be raised
and transported.
! Vehicles with automatic transmission
must not be tow-started. The transmission
may otherwise be damaged.
Observe the legal requirements for the rele-
vant countries when towing and tow-starting.
It is better to have the vehicle transported
than to have it towed. Vehicles with automatic transmission:
when
towing a vehicle, the transmission must
be in position N.
The battery must be connected and charged.
Otherwise, you:
R cannot turn the key in the ignition lock to
position 2
R vehicles with automatic transmission:
cannot shift the transmission to position N
i Deactivate the automatic locking feature
(Y page 223). You could otherwise be
locked out when pushing or towing the
vehicle.
Deactivate tow-away protection
(Y page 70) before the vehicle is towed. Fitting/removing the towing eye
Fitting the towing eye X
Remove the towing eye from the stowage
space.
The towing eye is located with the vehicle
tool kit under the luggage compartment
floor ( Y page 299). Towing and tow-starting
311
Breakdown assistance Z

Vehicles with a TIREFIT kit: the towing eye
is
located under the tyre inflation compres-
sor.
X Press the mark on cover : inwards in the
direction of the arrow.
X Remove cover : from the opening.
X Screw the towing eye in clockwise to the
stop and tighten it.
Vehicles with a trailer tow hitch do not have
a bracket for the screw-in towing eye at the
back.

If you intend to use the vehicle for tow-
ing, fold out the ball coupling ( Y page 203)
and secure the towbar to it.
Removing the towing eye X
Loosen the towing eye and unscrew it.
X Attach cover : to the bumper and press
until it engages.
X Place the towing eye in the stowage well
under the luggage compartment floor
(Y page 299).
X Vehicles with a TIREFIT kit: replace the tyre
inflation compressor. Towing the vehicle with the front axle
raised
Only vehicles without 4MATIC can be
towed with the front axle raised.
! Vehicles

with 4MATIC must not be towed
with the front or rear axle raised; otherwise,
the transmission may be damaged.
Vehicles with 4MATIC may either be towed
away with both axles on the ground or be loa-
ded up and transported.
! The ignition must be switched off if you
are towing the vehicle with the front axle
raised. Intervention by ESP ®
could other-
wise damage the brake system.
X Turn the key to position 2 in the ignition
lock.
X When the vehicle is stationary, depress the
brake pedal and keep it depressed. X
Vehicles with manual transmission:
depress the clutch pedal fully and shift to
neutral.
or
X Vehicles with automatic transmission:
shift the automatic transmission to posi-
tion P.
X Release the brake pedal.
X Release the electric parking brake.
X Deactivate automatic locking
(Y page 223).
X Switch on the hazard warning lamps
(Y page 108).
X Turn the key in the ignition lock to position
0 and leave the key in the ignition lock.
When towing your vehicle with the front axle
raised, it is important that you observe the
safety instructions ( Y page 310). Towing the vehicle with both axles on
the ground
G
WARNING
The power assistance for the steering and the
brake force booster do not work when the
engine is not running. You will then need
much

more effort to brake and steer the vehi-
cle. Adapt your style of driving accordingly.
i In order to signal a change of direction
when towing with the hazard warning lamps
switched on, use the combination switch as
usual. In this case, only the turn signals for
the desired direction flash. When you reset
the combination switch, the hazard warn-
ing lamps start flashing again. 312
Towing and tow-starting
Breakdown assistance

Vehicles with automatic transmission:
the
automatic transmission automatically shifts
to position P when you open the driver's or
front-passenger door or when you remove the
key from the ignition lock. In order to ensure
that the automatic transmission stays in posi-
tion N when towing the vehicle, you must
observe the following points:
X Make sure that the vehicle is stationary.
X Turn the key to position 2 in the ignition
lock.
X Depress and hold the brake pedal.
X Shift the automatic transmission to posi-
tion N.
Vehicles with manual transmission:
X Turn the key to position 2 in the ignition
lock.
X Depress and hold the brake pedal.
X Engage neutral.
Vehicles with manual or automatic trans-
mission:
X Leave the key in position 2 in the ignition
lock.
X Release the brake pedal.
X Release the electric parking brake.
X Switch on the hazard warning lamps
(Y page 108).
It is important that you observe the safety
instructions when towing away your vehicle
(Y page 310). Transporting the vehicle
! Only

lash the vehicle down by the wheels
or wheel rims, not by parts of the vehicle
such as axle or steering components. Oth-
erwise, the vehicle could be damaged. X
Vehicles with manual transmission:
shift to neutral.
X Vehicles with automatic transmission:
turn the key to position 2 in the ignition
lock.
X Move the transmission to position N.
As soon as the vehicle is loaded:
X Prevent the vehicle from rolling away by
applying the electric parking brake.
X Vehicles with manual transmission:
engage first or reverse gear.
X Vehicles with automatic transmission:
shift the transmission to position P.
X Turn the key to position 0 in the ignition
lock and remove it.
X Secure the vehicle.
The towing eyes or trailer tow hitch can be
used
to pull the vehicle onto a trailer or trans-
porter if you wish to transport it. Notes for 4MATIC vehicles
! Vehicles

with 4MATIC must not be towed
with the front or rear axle raised; otherwise,
the transmission may be damaged.
Vehicles with 4MATIC may only be either
towed away with both axles on the ground or
be loaded up and transported.
If the vehicle has transmission damage or
damage to the front or rear axle, have it trans-
ported on a transporter or trailer.
In the event of damage to the electrical
system
If the battery is defective, the automatic
transmission will be locked in position P. To
shift the automatic transmission to position
N, you must provide power to the vehicle's
electrical system in the same way as when
jump-starting (Y page 308).
Have the vehicle transported on a transporter
or trailer. Towing and tow-starting
313
Breakdown assistance Z

Tow-starting (emergency engine
starting)
! Do not tow-start vehicles with automatic
transmission.
You could otherwise damage
the automatic transmission.
Before tow-starting, the following conditions
must be fulfilled:
R the battery is connected.
R the engine has cooled down.
R the exhaust system has cooled down.
X Switch on the hazard warning lamps
(Y page 108).
X Fit the towing eye (Y page 311).
X Secure the rigid towing bar or the towing
rope.
X Depress and hold the brake pedal.
X Turn the key to position 2 in the ignition
lock.
X Depress the clutch pedal and keep it
depressed.
X Engage neutral.
X Release the brake pedal.
X Tow-start the vehicle.
X Engage second gear.
X Release the clutch pedal slowly without
depressing the accelerator pedal.
The engine is started.
X Depress the clutch pedal and shift to neu-
tral.
X Stop at a suitable place.
X Secure the vehicle by applying the electric
parking brake.
X Remove the rigid towing bar or towing rope.
X Remove the towing eye (Y page 312).
X Switch off the hazard warning lamps.
When tow-starting, it is important that you
observe the safety instructions ( Y page 310)
and the legal requirements for the relevant
countries. Electrical fuses
Important safety notes
G
WARNING
If you manipulate, bridge or replace a faulty
fuse with a fuse of a higher amperage, the
electric

cables could be overloaded. This may
result in a fire. There is a risk of an accident
and injury.
Always replace faulty fuses with specified new
fuses of the correct amperage.
! Only use fuses that have been approved
for Mercedes-Benz vehicles and which
have the correct fuse rating for the system
concerned. Only use fuses marked with an
"S". Components or systems could other-
wise be damaged.
The fuses in your vehicle serve to disconnect
faulty circuits. If a fuse blows, all the compo-
nents on the circuit and their functions will
fail.
Blown fuses must be replaced with fuses of
the same rating, which you can recognise by
the colour and fuse rating. The fuse ratings
are listed in the fuse allocation chart.
If the newly inserted fuse also blows, have the
cause traced and rectified at a qualified spe-
cialist workshop, e.g. a Mercedes-Benz
Service Centre. Before replacing a fuse
X Secure the vehicle against rolling away
(Y page 162).
X Switch off all electrical consumers.
X Turn the key to position 0 in the ignition
lock and remove it (Y page 143). All indi-
cator

lamps in the instrument cluster must
be off.
The fuses are located in various fuse boxes:
R fuse

box in the engine compartment on the
left-hand side of the vehicle, when viewed
in the direction of travel
R fuse box in the front-passenger footwell314
Electrical fuses
Breakdown assistance

Do not use high-pressure cleaners with circu-
lar-jet
nozzles to clean the vehicle. Have dam-
aged tyres or chassis components replaced
immediately. Fitting a wheel
Preparing the vehicle X
Stop the vehicle on solid, non-slippery and
level ground.
X Apply the electric parking brake manually
(Y page 163).
X Bring the front wheels into the straight-
ahead position.
X Vehicles with manual transmission:
engage first or reverse gear.
X Vehicles with automatic transmission:
move the DIRECT SELECT lever to P.
X Switch off the engine.
X Remove the key from the ignition lock.
X If a trailer is coupled to the vehicle, uncou-
ple it.
X If included in the vehicle equipment,
remove the tyre-change tool kit from the
vehicle.
X Secure the vehicle to prevent it from rolling
away.
i Apart
from certain country-specific varia-
tions, vehicles are not equipped with a tyre-
change tool kit. For information on which
tools are required to perform a wheel
change on your vehicle, consult a
Mercedes-Benz Service Centre.
Necessary wheel-changing tools can
include, for example:
R Jack
R Wheel chock
R Wheel wrench Securing the vehicle against rolling
away
If your vehicle is equipped with a wheel chock,
it can be found in the tyre-change tool kit
(Y page 299).
The folding wheel chock is an additional
securing

measure to prevent the vehicle from
rolling away, for example when changing a
wheel.
X Fold both plates upwards :.
X Fold out lower plate ;.
X Guide the lugs on the lower plate fully into
the openings in base plate =. Securing the vehicle on level ground
X
On level ground: place chocks or other
suitable items under the front and rear of
the wheel that is diagonally opposite the
wheel you wish to change. Changing a wheel
325
Wheels and tyres Z

Securing the vehicle on slight downhill gradients
X
On light downhill gradients: place
chocks or other suitable items in front of
the wheels of the front and rear axle.
Raising the vehicle G
WARNING
If you do not position the jack correctly at the
appropriate jacking point of the vehicle, the
jack could tip over with the vehicle raised.
There is a risk of injury.
Only
position the jack at the appropriate jack-
ing point of the vehicle. The base of the jack
must be positioned vertically, directly under
the jacking point of the vehicle.
Observe the following when raising the
vehicle:
R to raise the vehicle, only use the vehicle-
specific jack that has been tested and
approved by Mercedes-Benz. If the jack is
used incorrectly, it could tip over while the
vehicle is raised.
R the jack is designed only to raise and hold
the vehicle for a short time while a wheel
is being changed. It is not suitable for per-
forming maintenance work under the vehi-
cle.
R avoid changing the wheel on uphill and
downhill slopes.
R before raising the vehicle, secure it from
rolling away by applying the parking brake
and positioning wheel chocks. Never
release the parking brake while the vehicle
is raised. R
the jack must be placed on a firm, flat and
non-slip surface. On a loose surface, a
large,

load-bearing underlay must be used.
On a slippery surface, a non-slip underlay
must be used, e.g. rubber mats.
R do not use wooden blocks or similar
objects as a jack underlay. Otherwise, the
jack will not be able to achieve its load-
bearing capacity due to the restricted
height.
R make sure that the distance between the
underside of the tyres and the ground does
not exceed 3 cm.
R never place your hands or feet under the
raised vehicle.
R never lie under the raised vehicle.
R never start the engine when the vehicle is
raised.
R never open or close a door or the tailgate
when the vehicle is raised.
R make sure that no persons are present in
the vehicle when the vehicle is raised. Steel wheel with wheel trim
X
Vehicles with steel wheels: carefully
reach into two of the wheel trim openings
and remove the wheel trim.
Vehicles with hub caps:
the hub cap covers
the wheel bolts. Before you can unscrew the
wheel bolts, you must remove the hub cap. 326
Changing a wheel
Wheels and tyres