battery MERCEDES-BENZ A CLASS 2012 Service Manual

G
WARNING
A discharged battery can freeze at tempera-
tures below freezing point. When jump-start-
ing
the vehicle or charging the battery, gases
can escape from the battery. There is a risk of
an explosion.
Allow the frozen battery to thaw out before
charging it or jump-starting.
! Only use battery chargers with a maxi-
mum charging voltage of 14.8 V.
! Only charge the battery using the jump-
start connection point.
The jump-starting connection point is in the
engine compartment (Y page 308).
X Open the bonnet (Y page 285).
X Connect the battery charger to the positive
terminal

and earth point in the same order
as when connecting the donor battery in
the jump-starting procedure
(Y page 308).
If the indicator/warning lamps do not light up
at low temperatures, it is very likely that the
discharged battery has frozen. In this case
you may neither jump-start the vehicle nor
charge the battery. The service life of a bat-
tery

that has been thawed could be reduced.
The starting characteristics may be impaired,
especially at low temperatures. Have the
thawed battery checked at a qualified spe-
cialist workshop.
Only charge the installed battery with a bat-
tery charger which has been tested and
approved by Mercedes-Benz. A battery
charger unit specially adapted for Mercedes-
Benz vehicles and tested and approved by
Mercedes-Benz is available as an accessory.
It permits the charging of the battery in its
installed position. Contact a Mercedes-Benz
Service Centre for information and availabil-
ity. Read the battery charger's operating
instructions before charging the battery. Battery (vehicle)
307
Breakdown assistance Z

Jump-starting
For the jump-starting procedure, use only the jump-starting connection point, consisting of a
positive terminal and an earth point, in the engine compartment. 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. 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
During the charging process, a battery produces 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 contact with
vehicle parts.
R Never place metal objects or tools on a battery.
R It

is important that you observe the described 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 disconnecting
the jump leads.
R Never connect or disconnect the battery terminals while the engine is running. G
WARNING
A discharged battery can freeze at temperatures below freezing point. When jump-starting the
vehicle
or charging the battery, gases can escape from the battery. There is a risk of an explosion.
Allow the frozen battery to thaw out before charging it or jump-starting. G
WARNING
Non-combusted fuel can collect in the exhaust system and ignite. There is a risk of fire. Avoid
repeated and lengthy starting attempts.
! Vehicles

with a petrol engine: avoid repeated and lengthy starting attempts. Otherwise,
the non-combusted fuel may damage the catalytic converter.
If the indicator/warning lamps do not light up at low temperatures, it is very likely that the
discharged battery has frozen. In this case you may neither jump-start the vehicle nor charge
the battery. The service life of a battery that has been thawed could be reduced. The starting 308
Jump-starting
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

Position number
B identifies the charged battery of the other vehicle or an equivalent jump-
starting device.
X Press together cover : of positive clamp ; and slide it back.
X Connect positive terminal ; on your vehicle to positive terminal = of donor battery B
using the jump lead, beginning with your own battery.
X Start the engine of the donor vehicle and run it at idling speed.
X Connect negative terminal ? of donor battery B to earth point A of your vehicle using
the jump lead, connecting the jump lead to donor battery B first.
X Start the engine.
X Before disconnecting the jump leads, let the engines run for several minutes.
X First, remove the jump leads from earth point A
and negative terminal ?, then from pos-
itive clamp ; and positive terminal =. Begin each time at the contacts on your own vehicle
first.
X Close cover : of positive clamp ; after removing the jump leads.
X Have the battery checked at a qualified specialist workshop.
i Jump-starting is not considered to be a normal operating condition.
i Jump-starting cables and further information regarding jump starting can be obtained at
any qualified specialist workshop. Towing and tow-starting
Important safety notes
G
WARNING
Safety-relevant functions are restricted or not
available if:
R the engine is not running.
R the brake system or the power steering is
malfunctioning
R the

voltage supply or the vehicle's electrical
system is malfunctioning.
If your vehicle is towed, significantly greater
force may be required to steer the vehicle or
to brake. There is a risk of an accident.
In such circumstances, use a towing bar.
Make sure that the steering is moving freely
before towing. G
WARNING
If the weight of the vehicle to be towed or tow-
started is greater than the permissible gross
weight of your vehicle:
R the towing eye could detach itself
R the

vehicle/trailer combination could over-
turn.
There is a risk of an accident.
When towing or tow-starting another vehicle,
its weight should not be greater than the per-
missible gross weight of your vehicle.
Information on your vehicle's gross vehicle
weight rating can be found on the vehicle
identification plate ( Y page 338). G
WARNING
The vehicle is braked when the HOLD function
or DISTRONIC PLUS is activated. Therefore,
deactivate

HOLD and DISTRONIC PLUS if the
vehicle is to be towed. 310
Towing and tow-starting
Breakdown assistance

!
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 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