light MERCEDES-BENZ A CLASS 2012 Owner's Manual

SRS (Supplemental Restraint System)
Introduction Supplemental Restraint System (SRS) with:
R
The 6 SRS warning lamp
R Airbags
R Airbag control unit (with crash sensors)
R Belt
tensioners for the front seat belts and
the outer seat belts in the rear
R Seat belt force limiters for the front seat
belts and the outer seat belts in the rear
SRS reduces the risk of occupants coming
into contact with parts of the vehicle's interior
in the event of an accident. It can also reduce
the forces to which occupants are subjected
during an accident.
SRS warning lamp G
WARNING
If SRS is malfunctioning, individual systems
may
be triggered unintentionally or might not
be triggered in the event of an accident with
a high rate of vehicle deceleration.
A malfunction has occurred if:
R the 6 SRS warning lamp does not light
up when the ignition is switched on.
R the engine is running and the 6 SRS
warning lamp does not go out after a few
seconds.
R the engine is running and the 6 SRS
warning lamp lights up again.
In this case, have SRS checked immediately
at a qualified specialist workshop.
The 6 SRS warning lamp in the instrument
cluster lights up when the ignition is switched
on. It goes out no later than a few seconds
after the engine is started.
SRS functions are checked regularly when the
ignition is switched on or the engine is run-
ning. Therefore, malfunctions can be detec-
ted in good time. Triggering of belt tensioners and air-
bags During the first stage of a collision, the airbag
control unit evaluates important physical
data

relating to vehicle deceleration or accel-
eration, such as:
R duration
R direction
R magnitude
Based on the evaluation of this data, the air-
bag control unit pre-emptively triggers the
belt tensioners in the first stage.
If there is an even higher rate of vehicle decel-
eration or acceleration in a longitudinal direc-
tion, the front airbags are also deployed.
Your vehicle has adaptive, two-stage front air-
bags. The airbag control unit evaluates vehi-
cle deceleration or acceleration in the event
of a collision. In the first deployment stage,
the front airbag is filled with enough propel-
lant gas to reduce the risk of injuries. The
front airbag is fully deployed if a second
deployment threshold is reached within a few
milliseconds.
The belt tensioner and airbag triggering
thresholds are variable and are adapted to the
detected rate of deceleration or acceleration
of the vehicle. This process is pre-emptive in
nature. The triggering process must take
place in good time at the start of the collision.
The rate of vehicle deceleration or accelera-
tion and the direction of the force are essen-
tially determined by:
R the distribution of forces during the colli-
sion
R the collision angle
R the deformation characteristics of the vehi-
cle
R the characteristics of the object with which
the vehicle has collided
Factors which can only be seen and measured
after a collision has occurred do not play a
decisive role in the deployment of an airbag, Occupant safety
41
Safety Z

R
do not lean forwards, e.g. over the cover of
the driver's/front-passenger front airbag,
particularly when the vehicle is in motion.
R do not put your feet on the dashboard.
R only hold the steering wheel on the outside.
This allows the airbag to be fully deployed.
You could be injured if the airbag is
deployed and you are holding the inside of
the steering wheel.
R do not lean on the doors from inside the
vehicle.
R make sure that there are no people, ani-
mals or objects between the vehicle occu-
pants and the area where the airbags are
deployed.
R do not place any objects between the seat
backrest and the door.
R do not hang any hard objects, e.g. coat
hangers, on the grab handles or coat hooks.
R do not attach accessories, e.g. cup holders,
to the doors.
It is not possible to rule out a risk of injury
being caused by an airbag, due to the high
speed at which the airbag must be deployed. G
WARNING
Airbag functionality can only be assured if the
following
parts are not covered and no badges
or stickers are attached to them:
R padded steering wheel boss
R kneebag cover below the steering column
R front-passenger airbag cover
R outer side of front seat bolsters
R side trim next to the rear seat backrest
R roof frame cover between the front A-pillar
and the C-pillar in the rear compartment G
WARNING
When an airbag deploys, a small amount of
powder is released. The powder may cause
short-term breathing difficulties to persons
suffering from asthma or other pulmonary
conditions. In order to prevent potential breathing diffi-
culties, you should leave the vehicle as soon
as it is safe to do so. You can also open the
window

to allow fresh air to enter the vehicle
interior. The powder does not constitute a
health hazard and does not indicate that there
is a fire in the vehicle. G
WARNING
The airbag parts are hot after the airbag has
been deployed. Do not touch them as you
could burn yourself.
Have the airbags replaced at a qualified spe-
cialist workshop. Otherwise, occupants are
not protected by the airbags in the event of
another accident.
Airbag deployment slows down and restricts
the movement of the vehicle occupant.
If the airbags are deployed, you will hear a
bang

and a small amount of powder may also
be released. Only in rare cases will the bang
affect your hearing. The powder that is
released generally does not constitute a
health hazard. The 6 SRS warning lamp
lights up.
The airbag installation locations are identified
by the AIRBAG symbol.
Front airbags !
Do not place heavy objects on the front-
passenger seat. The system may then
detect

that the seat is occupied and if there
is an accident, the restraint systems on the
front-passenger side could be deployed.
Have restraint systems that have been trig-
gered replaced. Occupant safety
43
Safety Z

Driver's airbag
: deploys in front of the
steering wheel; front-passenger front air-
bag ;
deploys in front of and above the glove
compartment.
The front airbags increase protection for the
driver's and front-passenger's head and
chest.
They are deployed:
R at the start of an accident with a high rate
of vehicle acceleration or deceleration in a
longitudinal direction
R if the system determines that airbag
deployment can offer additional protection
to that provided by the seat belt
R depending on whether the seat belt is being
used
R independently of other airbags in the vehi-
cle
If the vehicle overturns, the front airbags are
generally not deployed.
Vehicles with automatic child seat recog-
nition in the front-passenger seat: front-
passenger airbag ; is only activated if the
system determines that the front-passenger
seat is occupied. The 4 PASSENGER AIR-
BAG OFF indicator lamp on the centre con-
sole does not light up (Y page 52). If a child restraint system is fitted to the front-
passenger

seat and the PASSENGER AIRBAG
OFF 4 indicator lamp on the centre con-
sole is not on:
R a child restraint system without a trans-
ponder for automatic child seat recognition
has been fitted or
R a child restraint system with a transponder
has been fitted incorrectly
Driver's kneebag Driver's kneebag
:
deploys under the steer-
ing column. The driver's kneebag is triggered
together with the front airbag. The driver's
kneebag is designed to operate together with
the front airbag in frontal impacts if certain
thresholds are exceeded. The driver's knee-
bag operates best in conjunction with cor-
rectly positioned and fastened seat belts.
Driver's kneebag : increases the driver's
protection against:
R knee injuries
R thigh injuries
R lower leg injuries
Sidebags G
WARNING
If you wish to use seat covers, Mercedes-Benz
recommends that, for safety reasons, you
only

use seat covers that have been approved
for Mercedes-Benz vehicles.
The seat covers must have a special tear seam
for sidebags. Otherwise, the sidebags cannot 44
Occupant safety
Safety

PRE-SAFE
®
takes pre-emptive measures to
protect occupants in certain hazardous sit-
uations.
PRE-SAFE ®
intervenes:
R when BAS activates, e.g. in emergency
braking situations
R when adaptive Brake Assist intervenes
powerfully on vehicles with DISTRONIC
PLUS
R in
critical driving situations, e.g. when phys-
ical limits are exceeded and the vehicle
understeers or oversteers severely
PRE-SAFE ®
takes the following measures
depending on the hazardous situation detec-
ted:
R the front seat belts are pre-tensioned.
R vehicles with the memory function: the
front-passenger seat is adjusted if it is in an
unfavourable position.
R if the vehicle skids, the panorama sliding
sunroof and the side windows are closed so
that only a small gap remains.
If the hazardous situation passes without
resulting in an accident, PRE-SAFE ®
slackens
the belt pretensioning. All settings made by
PRE-SAFE ®
can then be reversed.
If the seat belts are not released:
X Move the backrest or seat back slightly, but
only when the vehicle is stationary.
The belt pretensioning is reduced and the
locking mechanism is released.
More information about seat belt adjustment,
a convenience function integrated into PRE-
SAFE

(Y page 47). Seat belts
Important safety notes 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. Under certain circumstan- ces, this could cause severe or even fatal inju-
ries in the event of an accident.
Therefore, make sure that all occupants — in
particular,

pregnant women — wear their seat
belts correctly at all times.
R The seat belt must fit snugly on your body
and must not be twisted.Therefore, avoid
wearing bulky clothing, e.g. a winter coat.
The shoulder section of the belt must be
routed across the centre of your shoulder
— on no account across your neck or under
your arm — and pulled tight against your
upper body. The lap belt must always pass
across your lap as low down as possible, i.e.
over your hip joints — not across your abdo-
men. If necessary, push the seat belt
slightly downwards and adjust it by pulling
it in the direction the seat belt retracts.
R Do not route the seat belt strap over sharp
or fragile objects. Please make sure that
such objects are not on or in your clothing,
e.g. spectacles, pens or keys etc. The seat
belt strap could become damaged and tear
during an accident and you or other vehicle
occupants could be injured.
R Only one person should use each seat belt
at any one time. Children must never travel
sitting on the lap of another occupant. The
child will not be secured in the event of an
accident, heavy braking or sudden change
of direction. This may result in the child or
other occupants being seriously or fatally
injured.
R Persons under 1.50 m tall cannot wear the
seat belts correctly. For this reason secure
persons less than 1.50 m tall in specially
designed, suitable restraint systems.
R Children under 1.50 m tall and younger
than twelve years of age cannot wear the
seat belts correctly. For this reason secure
them in special suitable child restraint sys-
tems installed on a suitable seat. Additional
information can be found in the Operating
Instructions in the chapter "Safety", "Chil-
dren in the Vehicle". Observe the installa-46
Occupant safety
Safety

The belt strap is tightened slightly when:
R
you engage the belt tongue in the belt
buckle
and you then turn the key to position
2 in the ignition lock.
R the key is in position 2 in the ignition lock
and you then engage the belt tongue in the
buckle.
The seat-belt adjustment will apply a certain
tightening force if any slack is detected
between the occupant and the seat belt. Do
not hold on to the seat belt tightly while it is
adjusting. You can switch the seat-belt
adjustment on and off in the on-board com-
puter ( Y page 225).
The seat-belt adjustment is an integral part of
the PRE-SAFE ®
convenience function. More
information about PRE-SAFE ®
can be found
in the "PRE-SAFE ®
(preventative occupant
protection)" section (Y page 45).
Belt height adjustment You can adjust the belt height for the front
seats. Adjust the belt to a height that allows
the upper part of the seat belt to be routed
across the centre of your shoulder.
X
To raise:
slide the belt sash guide upwards.
The belt sash guide engages in various posi-
tions.
X To lower: press and hold belt sash guide
release :.
X Slide the belt sash guide downwards.
X Let go of belt sash guide release : and
make sure that the belt sash guide has
engaged. Releasing the seat belts !
Make
sure that the seat belt is fully rolled
up. Otherwise, the seat belt or belt tongue
will be trapped in the door or in the seat
mechanism. This could damage the door,
the door trim panel and the seat belt. Dam-
aged seat belts can no longer fulfil their
protective function and must be replaced.
Visit a qualified specialist workshop. X
Press release button ?
on belt buckle =.
X Guide belt tongue ; back to belt sash
guide :.
Belt warning for the driver and front
passenger The
7
seat belt warning lamp in the instru-
ment cluster is a reminder for all occupants
to fasten their seat belts. It may light up con-
tinuously or flash. In addition, a warning tone
may sound.
The 7 seat belt warning lamp goes out and
the warning tone ceases when the driver and
the front passenger have fastened their seat
belt.
For certain countries only: regardless of
whether the driver and the front passenger
have fastened their seat belts, the 7 seat
belt warning lamp lights up for six seconds
after the engine is started. It then goes out if 48
Occupant safety
Safety

ates or accelerates rapidly in a lateral direc-
tion
R in
certain situations where the vehicle over-
turns and the system determines that it can
provide additional protection
If the airbags are deployed, you will hear a
bang, and a small amount of powder may also
be released. Only in rare cases will the bang
affect your hearing. The powder that is
released generally does not constitute a
health hazard. The 6 SRS warning lamp
lights up.
If the seat belt is also fitted with a belt force
limiter and this is triggered, the force exerted
by the seat belt on the vehicle occupant is
reduced.
The belt force limiters on the front seats are
synchronised with the front airbags, which
take on a part of the deceleration force. This
results in the load being distributed over a
greater area. Children in the vehicle
Child restraint systems
Important safety notes G
WARNING
To reduce the risk of serious or even fatal
injury to the child in the event of a sudden
change in direction, braking or an accident:
R children less than 1.50 m tall and under
twelve

years of age must always be secured
in special child restraint systems on a suit-
able vehicle seat. This is necessary
because the seat belts are not designed for
children.
R Do not drive with a child secured in a rear-
ward-facing child restraint system on the
front-passenger seat. Exception: if the vehi-
cle is equipped with automatic child seat
recognition on the front-passenger seat
and the child is secured in a child restraint
system with transponders for automatic
child seat recognition R
if you secure a forward-facing child
restraint system to the front-passenger
seat, you must move the front-passenger
seat as far back as possible.
R children

must never travel sitting on the lap
of another occupant. Due to the forces
which occur in the event of a sudden
change of direction, heavy braking or an
accident, it would not be possible to
restrain the child. The child could be thrown
against parts of the vehicle interior and be
seriously or even fatally injured. G
WARNING
The child restraint system cannot perform its
protective function if it is not correctly fitted
to

a suitable vehicle seat. The child cannot be
restrained in the event of an accident, heavy
braking or sudden changes of direction. The
child could be seriously or even fatally injured.
For this reason, when fitting a child restraint
system, observe the manufacturer's installa-
tion instructions and the correct use of the
child restraint system.
Child restraint systems should be fitted to the
rear seats. Children are generally better pro-
tected there.
The entire base of the child restraint system
must always rest on the seat cushion. There-
fore, never place objects, e.g. a cushion,
under the child restraint system.
Only use child restraint systems with the orig-
inal cover designed for them. Only replace
damaged covers with genuine Mercedes-Benz
covers.
We recommend the use of child restraint sys-
tems which have been approved for
Mercedes-Benz vehicles. G
WARNING
Do not leave children unsupervised in the
vehicle, even if they are secured in a child
restraint system. They could injure them-
selves

on parts of the vehicle. They could also
be seriously or even fatally injured by pro-
longed exposure to extreme heat or cold. 50
Children in the vehicle
Safety

Do not expose the child restraint system to
direct
sunlight. Parts of the child restraint sys-
tem could heat up and the child could burn
herself/himself on them.
If a child opens a door, the child or other per-
sons could be injured as a result. They could
get out and injure themselves or be injured by
a passing vehicle.
Observe the general notes on the HOLD func-
tion, which can be found under the same key-
word. G
WARNING
Unsecured or incorrectly positioned loads
increase the risk of injury for children and all
other occupants in the event of:
R an accident
R sudden braking
R a sudden change of direction
Do

not transport heavy or hard objects in the
vehicle interior unless they are secured. You
will find further information under "Loading
guidelines" in the index.
If a child is travelling in your vehicle, secure
the child using a child restraint system which
is appropriate to the size, age and weight of
the child. You should preferably fit the
restraint system to a suitable rear seat. Make
sure that the child is secured for the trip.
Mercedes-Benz recommends that you use
the listed child restraint systems
(Y page 58). You can obtain further infor-
mation about the correct child restraint sys-
tem from any Mercedes-Benz Service Centre.
i It is advisable to use Mercedes-Benz care
products to clean child restraint systems.
You can obtain information about this at
any Mercedes-Benz Service Centre. Child restraint system on the front-
passenger seat G
WARNING
If the front-passenger airbag is not disabled:
R a child secured in a child restraint system
on the front-passenger seat could be seri-
ously and even fatally injured by the front-
passenger airbag deploying. This is espe-
cially a risk if the child is in the immediate
vicinity

of the front-passenger airbag when
it deploys.
R never secure a child on the front-passenger
seat in a rearward-facing child restraint sys-
tem. Only secure a rearward-facing child
restraint system on a suitable rear seat.
R always move the front-passenger seat to
the rearmost position if you secure a child
in a forward-facing child restraint system
on the front-passenger seat.
The front-passenger airbag is not disabled:
R on vehicles without automatic child seat
recognition on the front-passenger seat
R in vehicles with automatic child seat rec-
ognition in the front-passenger seat, if no
special child restraint system with trans-
ponders for automatic child seat recogni-
tion in the front-passenger seat has been
fitted
R on vehicles with automatic child seat rec-
ognition on the front-passenger seat, if the
PASSENGER AIRBAG OFF indicator lamp
4 is not lit.
To make you aware of this danger, a corre-
sponding warning sticker has been affixed on
the dashboard and on both sides of the sun
visor on the front-passenger side.
Information about recommended child
restraint systems is available at any
Mercedes-Benz Service Centre. Children in the vehicle
51
Safety Z

Warning notice on the front-passenger sun visor
Warning symbol for a rearward-facing child
restraint system
Do not use a rearward-facing child restraint
system on a seat that is protected by an air-
bag installed in front of it.
Automatic
child seat recognition on the
front-passenger seat G
WARNING
If the 4 PASSENGER AIRBAG OFF indica-
tor lamp does not light up when the child
restraint

system is fitted, the front-passenger
airbag has not been disabled. If the front-
passenger airbag deploys, the child could be
seriously or even fatally injured.
Proceed as follows:
R do not use a rearward-facing child restraint
system on the front-passenger seat.
R fit a rearward-facing child restraint system
on a suitable rear seat.
or R
only use a forward-facing child restraint
system on the front-passenger seat and
move the front-passenger seat to the rear-
most position.
R have the automatic child seat recognition
checked

at a qualified specialist workshop.
To ensure that the automatic child seat rec-
ognition on the front-passenger seat func-
tions/communicates correctly, never place
objects, e.g. a cushion, under the child
restraint system. The entire base of the child
restraint system must always rest on the seat
cushion. An incorrectly fitted child restraint
system cannot perform its intended protec-
tive function in the event of an accident, and
could lead to injuries. G
WARNING
Do not place electronic devices on the front-
passenger seat, e.g.:
R laptops, when switched on
R mobile phones
R cards

with transponders, e.g. ski passes or
access cards
Signals from electronic equipment can cause
interference in the automatic child seat rec-
ognition sensor system. This can lead to a
system malfunction. This may cause the
4 PASSENGER AIRBAG OFF indicator
lamp to light up without there being a child
seat with transponders for automatic child
seat recognition fitted. The front-passenger
airbag will not then deploy during an accident.
It is also possible that the 6 SRS warning
lamp lights up and/or the 4 PASSENGER
AIRBAG OFF indicator lamp does not light up
briefly when you turn the key in the ignition
lock to position 2.52
Children in the vehicle
Safety

If the front-passenger seat of your vehicle
does not have automatic child seat recogni-
tion,
this is indicated by a special sticker. The
sticker is affixed to the side of the dashboard
on the front-passenger side. The sticker is
visible when you open the front-passenger
door.
Vehicles without automatic child seat recog-
nition on the front-passenger seat: if you turn
the key to position 2 in the ignition lock, the
45 indicator lamp lights up briefly but
has no function. It does not indicate that there
is automatic child seat recognition on the
front-passenger seat. The sensor system for child restraint systems
in the front-passenger seat detects whether
a special Mercedes-Benz child seat with a
transponder for automatic child seat recog-
nition has been fitted. In this case,
45 indicator lamp
: lights up. The
front-passenger front airbag is disabled. i
If the front-passenger front airbag is dis-
abled by the automatic child seat recogni-
tion, the following remain enabled on the
front-passenger side:
R the sidebag
R the windowbag
R the belt tensioner
ISOFIX child seat securing system for
the rear seats G
WARNING
A child restraint system secured by the ISOFIX
child seat securing system does not provide
sufficient protection for children weighing
more than 22 kg

. For this reason, do not
secure children weighing more than 22 kg in
a child restraint system secured by the ISOFIX
child seat securing system. If the child weighs
more than 22 kg, secure the child restraint
system with the vehicle seat belt as well. In
addition, when fitting a child restraint system,
be sure to observe the manufacturer's instal-
lation instructions and the instructions for
correct use of the child restraint system. G
WARNING
The child restraint system cannot perform its
protective function if it is not correctly fitted
to

a suitable vehicle seat. The child cannot be
restrained in the event of an accident, heavy
braking or sudden changes of direction. The
child could be seriously or even fatally injured.
For this reason, when fitting a child restraint
system, be sure to observe the manufactur-
er's installation instructions and the instruc-
tions for correct use of the child restraint sys-
tem.
For safety reasons, when installing child
restraint systems on the rear seats, only use
child restraint systems with the ISOFIX child
seat securing system, which are specially tes-
ted and approved for Mercedes-Benz vehi-
cles.
An incorrectly fitted child restraint system
could come loose and seriously or even fatally Children in the vehicle
53
Safety
Z

Vehicles without adjustable head
restraints:
X
Top Tether belt with one belt strap: route
Top Tether belt = centrally over head
restraint .
or
X Top Tether belt with two belt straps:
route Top Tether belts = on the left and
right past the side of head restraint .
X Hook Top Tether hook ;
of Top Tether belt
= into Top Tether anchorage :.
Ensure that:
R Top Tether hook ; is hooked into Top
Tether anchorage : as shown.
R Top Tether belt = is not twisted.
R Top Tether belt = is routed between rear
seat backrest and luggage compartment
cover if luggage compartment cover is
fitted.
X Vehicles with adjustable head
restraints: move the head restraint back
down slightly again if necessary
(Y page 96). Make sure that you do not
interfere with the correct routing of Top
Tether belt =.
X Fit the ISOFIX child restraint system with
Top Tether. Comply with the manufactur-
er's

installation instructions when doing so.
Make sure that Top Tether belt = is tight. Children in the vehicle
55
Safety Z