MERCEDES-BENZ C-Class COUPE 2014 CL204 Service Manual

SRS (Supplemental Restraint System)
Introduction SRS consists of:
R
The 001E SRS warning lamp
R Air bags
R Air bag control unit (with crash sensors)
R Emergency Tensioning Devices
R Belt force limiters
SRS reduces the risk of occupants coming
into contact with the vehicle's interior in the
event of an accident. It can also reduce the
effect of the forces to which occupants are
subjected during an accident.
SRS warning lamp G
WARNING
If SRS is malfunctioning, child restraint
system components may be triggered
unintentionally or might not be triggered at all
in the event of an accident with a high rate of
vehicle deceleration. There is an increased
risk of injury, possibly even fatal.
Have SRS checked and repaired immediately
at a qualified specialist workshop.
SRS functions are checked regularly when
you switch on the ignition and when the
engine is running. Therefore, malfunctions
can be detected in good time.
The 001E 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.
The SRS components are in operational
readiness when the 001ESRS warning lamp
goes out while the engine is running. There is a malfunction if:
R
the 001E SRS warning lamp does not light
up when the ignition is switched on
R the engine is running and the 001ESRS
warning lamp does not go out after a few
seconds
R the engine is running and the 001ESRS
warning lamp lights up again
Safety guidelines for seat belts,
Emergency Tensioning Devices (ETDs)
and air bags G
WARNING
R Damaged seat belts or seat belts that have
been subjected to stress in an accident
must be replaced. Their anchoring points
must also be checked. Only use seat belts
installed or supplied by an authorized
Mercedes-Benz Center.
R Air bags and pyrotechnic Emergency
Tensioning Devices (ETDs) contain
perchlorate material, which may require
special handling and regard for the
environment. Check your national disposal
guidelines. California residents, see
www.dtsc.ca.gov/HazardousWaste/
Perchlorate/index.cfm .
R Air bags and ETDs are designed to function
on a one-time-only basis. An air bag or ETD
that has deployed must be replaced.
R Do not pass seat belts over sharp edges.
They could tear.
R Do not make any modification that could
change the effectiveness of the seat belts.
R Do not bleach or dye seat belts as this may
severely weaken them. In a crash they may
not be able to provide adequate protection.
R No modifications of any kind may be made
to any components or wiring of the SRS.
R Do not change or remove any component
or part of the SRS.
R Do not install additional trim material, seat
covers, badges, etc. over the steering
wheel hub, front-passenger front air bag Occupant safety
39Safety
Z

cover, outer sides of the sea
tbackrests,
door trim panels, or door frame trims.
R Do no tinstall additional electrical/
electronic equipment on or near SRS
components and wiring.
R Keep area between ai rbags and occupants
free of objects (e.g. packages, purses,
umbrellas, etc.).
R Do no thang items such as coat hangers
from the coat hooks or handles over the
door .These items may be thrown around in
the vehicle and cause head and other
injuries when the window curtain air bag is
deployed.
R Air bag system components will be hot after
an air bag has inflated. Do not touch them.
R Never place your feet on the instrument
panel, dashboard, or on the seat. Always
keep both feet on the floor in front of the
seat.
R Improper repair work on the SRS creates a
risk of rendering the SRS inoperative or
causing unintended air bag deployment.
Work on the SRS must therefore only be
performed by qualified technicians.
Contact an authorized Mercedes-Benz
Center.
R For your protection and the protection of
others, when scrapping the air bag unit or
ETD, our safety instructions must be
followed. These instructions are available
from any authorized Mercedes-Benz
Center.
R Given the considerable deployment speed,
required inflation volume, and the material
of the air bags, there is the possibility of
abrasions or other, potentially more serious
injuries resulting from air bag deployment.
If you sell your vehicle, Mercedes-Benz
strongly recommends that you inform the
subsequent owner that the vehicle is
equipped with SRS. Also, refer them to the
applicable section in the Operator's Manual. Air bags
Important safety notes G
WARNING
Using unsuitable seat covers could restrict or
even prevent deployment of the air bags
integrated into the seats. Consequently, the
air bags cannot protect vehicle occupants as
they are designed to do. In addition, the
function of the air bag deactivation system
could be restricted. This poses an increased
risk of injury or even fatal injury.
You should only use seat covers that have
been approved for the respective seat by
Mercedes-Benz. G
WARNING
The air bag parts are hot after the airbag has
been deployed. There is a risk of injury.
Do not touch the air bag parts. Have the
deployed air bags replaced at a qualified
specialist workshop as soon as possible. G
WARNING
Air bags are designed to reduce the incidence
of injuries and fatalities in certain situations:
R frontal impacts (driver's and front-
passenger front air bags and driver's knee
bag)
R side impacts (side impact air bags, window
curtain air bags and pelvis air bags)
However, no system available today can
completely eliminate injuries and fatalities.
When the air bags are deployed, a small
amount of powder is released. The powder
generally does not constitute a health hazard
and does not indicate that there is a fire in the
vehicle. In order to prevent potential
breathing difficulties, you should leave the
vehicle as soon as it is safe to do so. If you
have any breathing difficulty but cannot get
out of the vehicle after the air bag inflates,
then get fresh air by opening a window or
door. 40
Occupant safetySafety

G
WARNING
In order to reduce the potential dange rof
injuries caused during the deploymen tofthe
front air bags, the driver and front passenger
must always be correctly seated and wear
their seat belts.
For maximum protection in the event of a
collision, you must always be in the normal
seat position with your back against the
backrest. Fasten your seat belt and make sure
that it is correctly positioned on your body.
As the air bag inflates with considerable
speed and force, a proper seating position
and correct positioning of the hands on the
steering wheel will help to keep you at a safe
distance from the air bag. Occupants who are
not wearing their seat belt, are not seated
properly or are too close to the air bag can be
seriously injured or killed by an air bag, as it
inflates with great force instantaneously:
R sit with the seat belt fastened correctly and
in a position that is as upright as possible
with your back against the backrest.
R move the driver's seat as far back as
possible, still permitting proper operation
of vehicle controls. The distance from the
center of the driver's chest to the center of
the air bag cover on the steering wheel
must be at least 10 inches (25 cm). You
should be able to accomplish this by
adjusting the seat and steering wheel. If
you have any difficulties, please contact an
authorized Mercedes-Ben zCenter.
R do not lean your head or chest close to the
steering wheel or dashboard.
R only hold the steering wheel on the outside.
Placing hands and arms inside the rim can
increase the risk and potential severity of
hand/arm injury if the driver front air bag
inflates.
R adjust the front-passenger seat as far back
as possible from the dashboard when the
seat is occupied.
R occupants, especially children, should
never place their bodies or lean their heads
in the area of the door or the rear side trim panel where the side impact air bag
inflates
.This could result in serious or fatal
injuries should the side impact air bag be
deployed. Always sit as upright as possible,
wear the seat belt properly and use an
appropriately sized infant restraint, toddler
restraint or booster seat recommended for
the size and weight of the child.
Failure to follow these instructions can result
in severe injuries to you or other occupants.
If you sell your vehicle, it is important that you
make the buyer aware of this safety
information. Be sure to give the buyer this
Operator's Manual.
The air bag installation locations are
identified by the AIR BAG symbol.
The air bags are deployed if the air bag control
unit detects the need for deployment.O nly in
the event of such a situatio nwill the air bags
provide their supplemental protection.
If the drive rand front passenge rdo not wear
their seat belts, it is not possible for the air
bags to provide their supplemental
protection.
In the event of other types of impacts and
impacts below air bag deployment
thresholds, the air bags will not deploy. The
driver and passenger will then be protected
to the extentp ossible by a properly fastened
seat belt. Aproperly fastened seat belti s also
needed to provide the best possible
protection in a rollover.
Air bags provide additional protection; they
are not, however, a substitute for seat belts.
All vehicle occupants must fasten their seat
belts regardless of whether your vehicle is
equipped with air bags or not.
It is important for your safety and that of your
passenger to have deployed air bags replaced
and to have any malfunctioning air bags
repaired. This will help to make sure the air
bags continue to perform their protective
function for the vehicle occupants in the
event of a crash. Occupant safety
41Safety Z

i
After an ai rbag has been deployed, have
the vehicle towed to the neares tqualified
specialist workshop, eve nifyour vehicle is
ready to drive.
Front air bags The front air bags increase protection for the
driver's and front passenger's head and
chest.
Driver's air bag
0002deploys in front of the
steering wheel; front-passenger front air
bag 0003deploys in front of and above the glove
box.
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 air bag
deployment can offer additional protection
to that provided by the seat belt
R independently of other air bags in the
vehicle
The release time of the front air bags is
dependent upon the use of the seat belt.
Your vehicle has adaptive, two-stage front air
bags. In the event of a collision, the air bag
control unit evaluates the vehicle
deceleration. In the first deployment stage,
the front air bag is filled with enough
propellant gas to reduce the risk of injuries.
The front air bag is fully deployed if a second
deployment threshold is exceeded within a
few milliseconds. The deployment of front-passenger front air
bag
0003is also influenced by the weight
category of the front passenger, which is
determined by the Occupant Classification
System (OCS) (Y page 45).
The lighter the passenger-side occupant, the
higher the vehicle deceleration rate required
(predicted at the start of the impact) for
second stage inflation of the front-passenger
front air bag. In the second stage, the front
air bags are inflated with the maximum
amount of propellant gas available.
The front air bags are not deployed in
situations where a low impact severity is
predicted. You will then be protected by the
fastened seat belt.
The front-passenger front air bag will only be
deployed if:
R the system, based on the OCS weight
sensor readings, detects that the front-
passenger seat is occupied
R the PASSENGER AIR BAG OFF indicator
lamp on the center console is not lit
(Y page 45)
R the air bag control unit predicts a high-
impact severity
Driver's knee bag Driver's knee bag
0002increases the driver's
protection against:
R knee injuries
R thigh injuries
R lower leg injuries 42
Occupant safetySafety

Driver's knee bag
0002deploys under the
steering column. If, during a frontal collision,
the syste mdetermines that air bag
deployment can offer additional protection to
that provided by the seat belt, driver's knee
bag 0002is deployed along with the driver's air
bag. Driver's knee bag 0002operates best in
conjunction with correctly positioned and
fastened seat belts.
Side impact air bags G
WARNING
Using unsuitable seat cover scould restric tor
even preven tdeployment of the air bags
integrated into the seats. Consequently, the
air bags cannot protec tvehicle occupants as
they are designed to do. In addition, the
function of the air bag deactivation system
could be restricted. This poses an increased
risk of injury or even fatal injury.
You should only use seat covers that have
been approved for the respective seat by
Mercedes-Benz. G
WARNING
Sensors to control the air bags are located in
the doors. Modifications or work not
performed correctly to the doors or door
paneling, as well as damaged doors, can lead
to the function of the sensors being impaired.
The air bags might therefore not function
properly any more. Consequently, the air bags
cannot protec tvehicle occupants as they are
designed to do. There is an increased risk of
injury.
Never modify the doors or parts of the doors.
Always have work on the doors or door
paneling carried out at a qualified specialist
workshop.
You should only use seat covers that have
been approved for your vehicle by Mercedes-
Benz .The seat covers must have a special
tear seam for side impact air bags. Otherwise,
the side impact air bags cannot deploy
correctly and therefore cannot provide the intended protection in the event of an
accident.
When deployed, the side impact air bags offer
additional protection for the thorax of the
vehicle occupants on the side of the vehicle
on which the impact occurs. However, they
do not protect the:
R
head
R neck
R arms Front side impact air bags
0002and rear side
impact air bags 0003deploy next to the outer
seat cushions.
The side impact air bags are deployed:
R on the side on which an impact occurs
R at the start of an accident with a high rate
of lateral vehicle deceleration or
acceleration, e.g. in aside impact
R independently of the use of the seat belt
R independently of the front air bags
R independently of the ETDs
Side impac tair bags will not deploy in side
impacts which do not exceed the system's
prese tdeployment thresholds for lateral
acceleration/deceleration .You will then be
protected by the fastened seat belt.
The side impact air bag on the front-
passenger side is not deployed in the
following situations:
R OCS has detected that the front-passenger
seat is unoccupied.
R the front-passenger seat belt is not
fastened. Occupant safety
43Safety Z

The side impact air bag on the front-
passenger side will deploy if the front-
passenger seat belt is fastened, regardless of
whether the front-passenger seat is occupied
or not.
Pelvis air bags
G
WARNING
Only use seat covers which have been tested
and approved by Mercedes-Benz for your
vehicle model. Using seat covers or other seat
coverings can cause a malfunction of the side
impact air bags and/or the pelvis air bags.
Contact an authorized Mercedes-Benz Center
for availability.
Pelvis air bag deployment enhances the level
of protection of the vehicle occupants on the
side of the vehicle on which the impact
occurs. Pelvis air bags
0002deploy next to and below
the outer seat cushions. They are deployed:
R on the side on which an impact occurs
R at the start of an accident with a high rate
of lateral vehicle deceleration or
acceleration, e.g. in aside impact
R independently of the use of the seat belt
R independently of the front air bags
R independently of the ETDs
Pelvis air bags 0002will not deploy in side
impacts which do not exceed the system's
prese tdeployment thresholds for lateral
acceleration/deceleration .You will then be
protected by the fastened seat belt. The pelvis air bag on the front-passenger side
is not deployed in the following situations:
R
OCS has detected that the front-passenger
seat is unoccupied.
R the front-passenger seat belt is not
fastened.
The pelvis air bag on the front-passenger side
will deploy if the front-passenger seat belt is
fastened, regardless of whether the front-
passenger seat is occupied or not.
Window curtain air bags The window curtain air bags enhance the level
of protection for the head, but not chest or
arms, of the vehicle occupants on the side of
the vehicle on which the impact occurs.
The window curtain air bags are integrated
into the side of the roof frame and deploy in
the area extending from the front door (A-
pillar) to the rear sidewall (C-pillar).
Window curtain air bags
0002are deployed:
R on the side on which an impact occurs
R at the start of an accident with a high rate
of lateral vehicle deceleration or
acceleration, e.g. in aside impact
R regardless of whether the front-passenger
seat is occupied
R independently of the use of the seat belt
R independently of the front air bags
Window curtain air bags 0002will not deploy in
the even tofimpacts which do not exceed the
system's preset deployment thresholds for 44
Occupant safetySafety

vehicle acceleration/deceleration. You will
then be protected by the fastened seat belt. Occupant Classification System
(OCS)
How the Occupant Classification
System works The Occupant Classification System (OCS)
categorizes the occupant on the front-
passenger seat using a weight sensor. The
front-passenge rfront air bag is deactivated
automatically for certain weight categories.
The PASSENGER AIR BAG OFF indicator lamp
shows you the current status. If the
PASSENGER AIR BAG OFF indicator lamp is
lit, the passenger air bag is disabled.
The system does not deactivate:
R the side impact air bag
R the pelvis air bag
R the window curtai nair bag
R the Emergency Tensioning Devices
To be classified correctly, the front passenger
must sit:
R with the seat belt fastened correctly
R in a position that is as upright as possible
with their back against the seat backrest
R with their feet on the floor
The OCS weight sensor reading is affected if
the occupant's weight is transferred, e.g. by
leaning on the armrest.
If the front-passenger seat, the seat cover or
the seat cushio nare damaged, have the
necessary repair work carried out at a
qualified specialist workshop.
For safety reasons, Mercedes-Benz
recommends that you only use seat
accessories that have been approved by
Mercedes-Benz.
Both the drive rand the front passenger
should always observe the PASSENGER AIR
BAG OFF indicator lamp as an indication of
whethe rornot the front passenger is
positioned correctly. Observe also the air bag display messages that can be displayed in the
instrument cluster (Y
page 213). G
WARNING
If the 0019001B indicator lamp illuminates
when an adult or someone larger than a small
individual is in the front passenger seat, have
the front passenger reposition himself or
herself in the seat until the 0019001B
indicator lamp goes out.
In the event of a collision, the air bag control
unit will not allow front passenger front air bag
deployment when the OCS has classified the
front passenger seat occupant as weighing as
much as or less than a typical 12-month-old
child in a standard child restraint or if the front
passenger seat is classified as being empty.
When the OCS senses that the front
passenger seat occupant is classified as
being up to or less than the weight of a typical
12-month-old child in a standard child
restraint, the 0019001Bindicator lamp will
illuminate when the engine is started and
remain illuminated. This indicates that the
front passenger front air bag is deactivated.
When the OCS senses that the front
passenger seat is classified as being empty,
the 0019001B indicator lamp will illuminate
when the engine is started and remain
illuminated. This indicates that the front
passenger front air bag is deactivated.
When the OCS senses that the front
passenger seat occupant is classified as
being heavier than the weight of a typical 12-
month-old child seated in astandard child
restraint or as being a small individual (such
as a young teenager or asmall adult), the
0019001B indicator lamp will illuminate for
approximately 6seconds when the engine is
started. Depending on occupant weight
sensor readings from the seat, it will then
remain illuminated or go out. With the
0019001B indicator lamp illuminated, the
fron tpassenger fron tair bag is deactivated.
With the 0019001B indicator lamp out, the
front passenger front air bag is activated. Occupant safety
45Safety
Z

When the OCS senses that the front
passenger seat occupant is classified as an
adult or someone larger than a small
individual, the
0019001Bindicator lamp will
illuminate for approximately six seconds
when the engine is started and then go out.
This indicates that the fron tpassenger front
air bag is activated.
If the 0019001B indicator lamp is illuminated,
the front passenger front air bag is
deactivated and will no tbedeployed.
If the 0019001B indicator lamp is not
illuminated, the fron tpassenger fron tair bag
is activated and will be deployed
R in the event of certain frontal impacts
R if the impact exceeds a predetermined
triggering threshold
R independen tofthe side impact air bag or
pelvis air bag
If the front passenger front air bag is
deployed, the rate of inflation will be
influenced by
R the rate of vehicle deceleration as assessed
by the air bag control unit
R the front passenger's weight category as
identified by the OCS G
WARNING
According to accident statistics, children are
safer when properly restrained on the rear
seats than on the front-passenger seat. Thus,
we strongly recommend that children be
placed in the rear seats whenever possible.
Regardless of seating position, children 12
years old and under must be seated and
properly secured in an appropriate infant
restraint, toddler restraint, or booster seat
recommended for the size and weight of the
child.
The infant or child restraint must be properly
secured with the vehicle's seat belt, the seat
belt and Top Tether strap, or lower anchors
and Top Tether strap, fully in accordance with
the child seat manufacturer's instructions. Occupants, especially children, should always
sit as upright as possible, wear the seat belt
properly and use an appropriately sized infant
restraint, toddler restraint, or booster seat
recommended for the size and weight of the
child.
Children can be killed or seriously injured by
an inflating air bag. Note the following
important information when circumstances
require you to place a child in the front-
passenger seat:
R Your vehicle is equipped with air bag
technology designed to deactivate the
front-passenger front air bag in your vehicle
when the system senses the weight of a
typical 12-month-old child or less along
with the weight of a standard appropriate
child restraint on the front-passenger seat.
R Ac hild in a rear-facing child restraint on the
front-passenger seat will be seriously
injured or even killed if the front-passenger
front air bag inflates in a collision which
could occur under some circumstances,
even with the air bag technology installed
in your vehicle. The only means to eliminate
this risk completely is never to place a child
in a rear-facing child restraint in the front-
passenger seat. We therefore strongly
recommend that you always place a child
in a rear-facing child restraint on the rear
seat.
R If you install a rear-facing child restraint on
the front-passenger seat, make sure the
0019001B indicator lamp is illuminated,
indicating that the front-passenger front air
bag is deactivated. Should the 0019001B
indicator lamp not illuminate or go out while
the restraint is installed, please check
installation. Periodically check the
0019001B indicator lamp while driving to
make sure that the 0019001Bindicator
lamp is illuminated. If the 0019001B
indicator lamp goes out or remains out, do
not transport a child on the front-passenger
seat until the system has been repaired. 46
Occupant safetySafety

Ac
hild in a rear-facing child restraint on the
front-passenger seat will be seriously
injured or even killed if the front-passenger
front air bag inflates.
R If you place a child in a forward-facing child
restraint on the front-passenger seat:
- move the seat as far back as possible
- use the proper child restraint
recommended for the age, size and
weight of the child
- secure child restraint with the vehicle's
seat belt according to the child seat
manufacturer's instructions
R For children larger than the typical 12-
month-old child, the front-passenger front
air bag may or may not be activated.
If the driver's air bag deploys, this does not
mean that the front-passenger front air bag
will also deploy.
The OCS may have detected that the seat:
R is empty or occupied by the weight of a
typical child up to twelve months old,
seated in a child restraint system.
R is occupied by a small individual, such as a
young teenager or a small adult.
R is occupied by a child in a child restraint
system whose weight is greater than that
of a typical twelve month old child.
These are examples of when the OCS
deactivates the front-passenger front air bag.
Deactivation takes place although the
collision fulfills the criteria for deploying the
driver's air bag. If the SmartKey is removed from the ignition
lock or is in position
0, the PASSENGER AIR
BAG OFF indicator lamp does not light up. G
WARNING
If the red 001ESRS warning lamp in the
instrument cluster and the 0019001B
indicator lamp light up simultaneously, the
OCS is malfunctioning. The front passenger
front air bag will be deactivated in this case.
Have the system checked by qualified
technicians as soon as possible. Contact an
authorized Mercedes-Ben zCenter.
Only have the seat repaired or replaced at an
authorized Mercedes-Benz Center.
In order to ensure proper operation of the air
bag system and OCS:
R Sit with the seat belt properly fastened in a
position that is as upright as possible with
your back against the seat backrest.
R When seated, a passenger should not
position him/herself in such a way as to
cause the passenger's weight to be lifted
from the seat cushion as this may result in
the OCS being unable to correctly
approximate the passenger's weight
category.
R Read and observe all warnings in this
chapter.
System self-test The PASSENGER AIR BAG OFF indicator lamp
lights up if you:
R
turn the SmartKey to position 1or 2in the
ignition lock
R press the KEYLESS-GO Start/Stop button
once or twice on vehicles with KEYLESS-
GO.
When an adult is sitting correctly on the front-
passenger seat and is categorized by the OCS
system as an adult, the PASSENGER AIR BAG
OFF indicator lamp lights up and goes off
again after approximately six seconds.
If the seat is not occupied and the OCS
system classifies the front-passenger seat as Occupant safety
47Safety Z

being empty, the PASSENGER AIR BAG OFF
indicator lamp will continue to light up and
not go out. G
WARNING
If the 0019001Bindicator lamp does not
illuminate, the system is not functioning. You
must contact an authorized Mercedes-Benz
Center before seating any child on the front
passenger seat.
For more information about the OCS, see
"Problems with the Occupant Classification
System" (Y page 49). G
WARNING
Objects betwee nthe seat surface and the
child restraint system could affect the
function of the OCS. This could result in the
front-passenger front air bag not functioning
as intended during an accident. This poses an
increased risk of injury or even fatal injury.
Do not place any objectsb etween the seat
surface and the child restraint system. Make
sure that the bottom and back of the child
restraint system make full contact with the
front-passenger seat cushion and backrest.
Always comply with the child restraint system
manufacturer's installation instructions. 48
Occupant safetySafety