MERCEDES-BENZ C-Class COUPE 2012 CL204 Service Manual

inflates. This could result in serious injuries
or death should the side impact air bag be
deployed. Always sit as upright as possible,
wear the seat belt properly and use an
appropriately sized child restraint, infant
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.GWARNING
Accident research shows that the safest place
for children in an automobile is in a rear seat.
A side impact air bag related injury may occur
if occupants, especially children, are not
properly seated or restrained when next to a
side impact air bag which needs to deploy
rapidly in a side impact in order to do its job.
To help avoid the possibility of injury, please
follow these guidelines:
(1)Always sit as upright as possible
and use the seat belts properly.
Make sure that children 12 years
old and under use an appropriately
sized child restraint, infant
restraint, or booster seat
recommended for the size and
weight of the child.(2)Always wear seat belts properly.
The air bags are only deployed if the air bag
control unit detects the need for deployment.
Only in the event of such a situation will they
provide their supplemental protection.
The driver and passenger should always wear
their seat belts. Otherwise, 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 passengers will then be protected
to the extent possible by a properly fastened
seat belt. A properly fastened seat belt is 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.
Front air bags
The front air bags increase protection for the
driver's and front-passenger's head and
chest.
Driver's air bag : deploys in front of the
steering wheel; front-passenger front air
bag ; deploys in front of and above the glove
box.
They are deployed:
R in the event of certain frontal impacts
R if the system determines that air bag
deployment can offer additional protection
to that provided by the seat belt
R if the seat belt is fastened
R independently of other air bags in the
vehicle
Occupant safety39SafetyZ

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 the front-passenger front
air bag is also influenced by the weight
category of the front passenger, which is
determined by the Occupant Classification
System (OCS) ( Y page 42).
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
deploy if:
R the system, based on the OCS weight
sensor readings, detects that the front-
passenger seat is occupied.
R the 45 indicator lamp in the center
console is not lit, ( Y page 42).
R the air bag control unit predicts a high
impact severity.Driver's knee bag
Driver's knee bag : provides additional
protection for the driver against:
R knee injuries
R thigh injuries
R lower leg injuries
Driver's knee bag : deploys below the
steering wheel. During a frontal impact, if the
system determines that air bag deployment
can offer additional protection to that
provided by the seat belt, driver's knee
bag : is deployed along with the driver's air
bag. The driver's knee bag : operates best
in conjunction with a properly positioned and
fastened seat belt.
Side impact air bags
GWARNING
The pressure sensors for side impact air bag
control are located in the doors. Do not
modify any components of the doors or door
trim panels including, for example, the
addition of door speakers.
Improper repair work on the doors or the
modification or addition of components to the
doors create a risk of rendering the side
impact air bags inoperative or causing
unintended air bag deployment. Work on the
doors must therefore only be performed by
qualified technicians. Contact an authorized
Mercedes-Benz Center.
40Occupant safetySafety

GWARNING
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.
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 : and rear side
impact air bags ; deploy 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 a side impact
R independently of seat belt use
R independently of the front air bags
R independently of the ETDs
Side impact air bags will not deploy in side
impacts which do not exceed the system's
preset deployment thresholds for lateral
acceleration/deceleration. You will then be
protected by the fastened seat belt.
If the OCS detects that the front-passenger
seat is not occupied and the front-passenger
seat belt is not fastened (the belt tongue is
not engaged in the seat belt buckle), the side
impact air bag on the front-passenger side
will not deploy. 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 bagsGWARNING
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 : deploy 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 a side impact
R independently of seat belt use
R independently of the front air bags
R independently of the ETDs
Occupant safety41SafetyZ

Pelvis air bags : will not deploy in side
impacts which do not exceed the system's
preset deployment thresholds for lateral
acceleration/deceleration. You will then be
protected by the fastened seat belt.
If the OCS detects that the front-passenger
seat is not occupied and the front-passenger
seat belt is not fastened (the belt tongue is
not engaged in the seat belt buckle), the
pelvis air bag on the front-passenger side will
not deploy. 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 : 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 a side impact
R regardless of whether the front-passenger
seat is occupied
R independently of seat belt use
R independently of the front air bags
Window curtain air bags : will not deploy in
impacts with deceleration rates which do not
exceed the system's preset deployment
thresholds for vehicle deceleration or
acceleration. 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 by means of a weight sensor.
The front-passenger front air bag is
deactivated automatically for certain weight
categories. The 45 indicator lamp
shows you the current status. If the
45 indicator lamp is illuminated, the
front-passenger front air bag is deactivated.
The system does not deactivate:
R the side impact air bag
R the pelvis air bag
R the window curtain air 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
If the front-passenger's weight is transferred
to another object in the vehicle (e.g. by
leaning on armrests), OCS may not be able to
approximate the occupant's weight category.
If the front-passenger seat, the seat cover or
the seat cushion are damaged, have the
necessary repair work carried out at an
authorized Mercedes-Benz Center.
For safety reasons, Mercedes-Benz
recommends that you only use seat
accessories which have been approved by
Mercedes-Benz.
42Occupant safetySafety

Both the driver and the passenger should
always use the 45 indicator lamp as
an indication of whether or not the passenger
is properly positioned.GWARNING
If the 45 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 45
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 45 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 is classified as being empty,
the 45 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 a standard child
restraint or as being a small individual (such
as a young teenager or a small adult), the
45 indicator lamp will illuminate for
approximately 6 seconds when the engine is
started. Depending on occupant weight
sensor readings from the seat, it will then
remain illuminated or go out. With the
45 indicator lamp illuminated, the
front passenger front air bag is deactivated.
With the 45 indicator lamp out, the
front passenger front air bag is activated.
When the OCS senses that the front
passenger seat occupant is classified as an
adult or someone larger than a small
individual, the 45 indicator lamp will
illuminate for approximately six seconds
when the engine is started and then go out.
This indicates that the front passenger front
air bag is activated.
If the 45 indicator lamp is illuminated,
the front passenger front air bag is
deactivated and will not be deployed.
If the 45 indicator lamp is not
illuminated, the front passenger front air 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 independent of the 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
For further information, see "Air bag display
messages" ( Y page 209).GWARNING
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.
Occupant safety43SafetyZ

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 A child 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
45 indicator lamp is illuminated,
indicating that the front-passenger front air
bag is deactivated. Should the 45
indicator lamp not illuminate or go out while
the restraint is installed, please check
installation. Periodically check the
45 indicator lamp while driving to
make sure that the 45 indicatorlamp is illuminated. If the 45
indicator lamp goes out or remains out, do
not transport a child on the front-passenger
seat until the system has been repaired.
A child 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
also has to deploy.
The OCS may have detected that the seat:
R was empty or occupied by a person with a
weight of up to or less than that of a typical
12-month-old child seated in a standard
child restraint
R was occupied by a small individual, such as
a young teenager or a small adult
R was occupied by a child in a child restraint
system, whose weight is greater than that
of a typical 12-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.44Occupant safetySafety

If the SmartKey has been removed from the
ignition lock or is in position 0, indicator lamp
45 : does not light up.
GWARNING
If the red 6 SRS warning lamp in the
instrument cluster and the 45
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-Benz Center.
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 45 indicator lamp illuminates
when you:
R turn the SmartKey to position 1 or 2 in the
ignition lock
R on vehicles with KEYLESS-GO, press the
Start/Stop button once or twice
If an adult occupant is properly sitting on the
passenger seat and the OCS classifies the
occupant as an adult, the 45 indicator
lamp illuminates and goes out again after
approximately 6 seconds.
If the seat is not occupied and the OCS
classifies the front passenger seat as being
unoccupied, the 45 indicator lamp
will illuminate and not go out.
GWARNING
If the 4 5 indicator 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, see "Problems with the
Occupant Classification System"
( Y page 46).
GWARNING
Never place anything between seat cushion
and child seat (e.g. a pillow), since it reduces
the effectiveness of the OCS. The underside
and rear side child restraint system must be
placed entirely on the seat cushion and the
backrest of the front-passenger seat
backrest.
If necessary, adjust the tilt of the passenger
seat backrest.
An incorrectly mounted child seat could cause
injuries to the child in case of an accident,
instead of increasing protection for the child.
Follow the manufacturer's instructions for
installation of child restraint systems.
Occupant safety45SafetyZ

Problems with the occupant classification systemProblemPossible causes/consequences and M SolutionsThe 45
indicator lamp
illuminates and
remains illuminated.
The person on the
front-passenger seat:
R has the weight of a
typical adult
R has been determined
by the system not to
be a child.The OCS is malfunctioning.XHave the OCS checked as soon as possible at an authorized
Mercedes-Benz Center.XObserve the additional display messages in the multifunction
display ( Y page 209).GWARNING
If the 45 indicator lamp illuminates and remains illuminated when the weight of a typical
adult or someone larger than a small individual has been detected on the passenger seat, do not
allow any occupant to use the passenger seat until the system has been repaired.
ProblemPossible causes/consequences and M SolutionsThe 45
indicator lamp does not
illuminate and/or does
not remain illuminated.
The front-passenger
seat is:
R unoccupied
R occupied with a
weight up to or less
than a typical 12-
month-old child in a
standard child
restraint systemThe OCS is malfunctioning.XMake sure there is nothing between the seat cushion and the
child seat.XCheck the installation of the child restraint system.XMake sure that no objects are applying additional weight onto
the seat.XIf the 45 indicator lamp does not illuminate, have the
OCS checked as soon as possible at an authorized Mercedes-
Benz Center. Do not transport a child on the front-passenger
seat as long as the OCS is not functioning.XObserve the additional display messages in the multifunction
display ( Y page 209).GWARNING
If the 45 indicator lamp does not illuminate or remains out with the weight of a typical
12-month-old child in a standard child restraint or less, or is unoccupied, on the front-passenger
seat, do not transport a child on the front-passenger seat until the system has been repaired.
46Occupant safetySafety

NECK-PRO head restraints
The NECK-PRO head restraints increase
protection to the driver's and front
passenger's head and neck. To this end, the
NECK-PRO head restraints on the driver's and
front-passenger seats are moved forwards
and upwards in the event of a rear-end
collision of a certain severity. This provides
better head support.GWARNING
Do not secure any objects (e.g. coat hangers)
on the NECK-PRO head restraints. Otherwise,
the NECK-PRO head restraints may not
function properly, or in the event of a rear-end
collision may not be able offer the level of
protection they are designed to provide.
GWARNING
Seat or head restraint covers can cause a
malfunction when the NECK-PRO head
restraints are activated or when the side
impact air bags or pelvis air bags are
deployed, or they can prevent this completely.
The NECK-PRO head restraints or side impact
air bags/pelvis air bags can therefore not
provide the intended protection. Do not use
any seat or head restraint covers.
If the NECK-PRO head restraints have been
triggered in an accident, reset the NECK-PRO
head restraints on the driver’s and front-
passenger seat ( Y page 47). Otherwise, the
additional protection will not be available in
the event of another rear-end collision. You
can recognize when NECK-PRO head
restraints have been triggered by the fact that
they have moved forwards and can no longer
be adjusted.
GWARNING
For your protection, drive only with properly
positioned head restraints.
Adjust the head restraint so that it is as close
to the head as possible and the center of the
head restraint supports the back of the head
at eye level. This will reduce the potential for
injury to the head and neck in the event of an
accident or similar situation.
Resetting triggered NECK-PRO head
restraints
GWARNING
For safety reasons, have the NECK-PRO head
restraints checked at an authorized
Mercedes-Benz Center after a rear-end
collision.
GWARNING
When pushing back the NECK-PRO head
restraint cushion, make sure your fingers do
not become caught between the head
restraint cushion and the cover. Failure to
observe this could result in injuries.
i Resetting the NECK-PRO head restraints
requires a lot of strength. If you have
difficulty resetting the NECK-PRO head
restraints, have this work carried out at a
qualified specialist workshop, e.g. an
authorized Mercedes-Benz Center.
XTilt the top of the NECK-PRO head restraint
cushion forwards in the direction of
arrow :.XPush the NECK-PRO head restraint cushion
down in the direction of arrow ; as far as
it will go.Occupant safety47SafetyZ

XFirmly push the NECK-PRO head restraint
cushion back in the direction of arrow =
until the cushion engages.XRepeat this procedure for the second
NECK-PRO head restraint.
Seat belts
Important safety notes
The use of seat belts and infant and child
restraint systems is required by law in all 50
states, the District of Columbia, the U.S.
territories and all Canadian provinces.
Even where this is not the case, all vehicle
occupants should have their seat belts
fastened when the vehicle is in motion.
i For further information on infants and
children traveling in the vehicle and on
infant and child restraint systems, see
"Children in the vehicle" ( Y page 52).
GWARNING
Always fasten your seat belt before driving off.
Always make sure all of your passengers are
properly restrained. You and your passengers
should always wear seat belts.
Failure to wear and properly fasten and
position your seat belt greatly increases your
risk of injuries and their likely severity in an
accident.
If you are ever in an accident, your injuries can
be considerably more severe without your
seat belt properly buckled. Without your seat
belt buckled, you are much more likely to hit
the interior of the vehicle or be ejected from
it. You can be seriously injured or killed.
In the same crash, the possibility of injury or
death is lessened if you are properly wearing
your seat belt. The air bags can only protect
as intended if the occupants are properly
wearing their seat belts.
GWARNING
Never ride in a moving vehicle with the seat
backrest in an excessively reclined position as
this can be dangerous. You could slide under
the seat belt in a collision. If you slide under
it, the seat belt would apply force at the
abdomen or neck. That could cause serious
or even fatal injuries. The seat backrest and
seat belt provide the best restraint when the
wearer is in a position that is as upright as
possible and the seat belt is properly
positioned on the body.GWARNING
Never let more people ride in the vehicle than
there are seat belts available. Make sure
everyone riding in the vehicle is correctly
restrained with a separate seat belt. Never
use a seat belt for more than one person at a
time.
GWARNING
Damaged seat belts or seat belts that have
been subjected to stress in an accident must
be replaced and their anchoring points must
also be checked.
Only use seat belts which have been approved
by Mercedes-Benz.
Do not make any modifications to the seat
belts. This can lead to unintended activation
of the ETDs or to their failure to activate when
necessary.
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.
Have all work carried out only by qualified
technicians. Contact an authorized
Mercedes-Benz Center.
Correct use of the seat belts
GWARNING
USE SEAT BELTS PROPERLY
R Seat belts can only work when used
properly. Never wear seat belts in any other
way than as described in this section, as
48Occupant safetySafety