MERCEDES-BENZ C-CLASS CABRIOLET 2021 Service Manual

te
m wa rning lamp lights up. It goes out no later
th an a few seconds af terth eve hicle is star ted.
The components of there stra int sy stem are then
functional. Malfunctioning
restra int sy stem A malfunction has occur
red in there stra int sys‐
te m if:
R the6 restra int sy stem warning lamp does
not light up when the ignition is switched on
R the6 restra int sy stem warning lamp
lights up continuously or repeatedly during a
journey &
WARNING Risk of inju rydue tomalfunc‐
tions in there stra int sy stem
Components in there stra int sy stem may be
activated unintentionally or not deploy as
intended in an accident. #
Have there stra int sy stem checked and
re paired immediately at a qualified spe‐
cialist workshop. Fu
nction of there stra int sy stem in an acci‐
dent How
there stra int sy stem works is de term ined by
th e se verity of the impact de tected and the type
of accident anticipated:
R Frontal impact
R Rear impact
R Side impact
R Rollover
The activation thre sholds forth e components of
th ere stra int sy stem are de term ined based on
th eev aluation of the sensor values measured at
va rious points in theve hicle. This process is pre-
em ptive in nature. The triggering/deployment of
th e components of there stra int sy stem must
ta ke place in good time at thest art of the colli‐
sion.
Fa ctors whi chcan only be seen and measu red
af te r a collision has occur red do not play a deci‐
sive role in the deployment of an airbag. Nordo
th ey prov ide an indication of airbag deployment.
The vehicle may be deformed significantly with‐
out an airbag being deplo yed. This is the case if only parts which are
relatively easily deformed
are af fected and thera te ofvehicle deceleration
is not high. Con versely, an airbag may be
deplo yedev en though theve hicle suf fers only
minor deformation. If very rigid vehicle parts
such as longitudinal members are hit, this may
re sult in suf ficiently high le vels of vehicle decel‐
eration.
Depending on the de tected deployment situa‐
tion, the components of there stra int sy stem can
be activated or deplo yed independently of each
ot her:
R Seat belt tensioner: frontal impact, rear
impact, side impact, rollo ver
R Driver's airbag, front passenger airbag: fron‐
talimpact
R Knee airbag: frontal impact
R Side airbag: side impact
R Head airbag: side impact, rollo ver,frontal
impact
The front passenger airbag can only be depl oyed
in an accident if thePA SSENGER AIR BAG OFF
indicator lamp is off. If the front passenger seat 38
Occupant saf ety

is occupied, make sure, bo
thbefore and during
th e journe y,that thest atus of the front
passenger airbag is cor rect (/ page 49). &
WARNING Risk of bu rns from hot airbag
components
The airbag parts are hot af ter an airbag has
been depl oyed. #
Do not touch the airbag parts. #
Have a deplo yed airbag replaced at a
qu alified specialist workshop as soon
as possible. Mercedes-Benz
recommends that you ha vethe
ve hicle towe dto aqu alified specialist workshop
af te r an accident. Take this into account, partic‐
ularly if a seat belt tensioner is trig gered or an
airbag deplo yed.
If th e seat belt tensioners are trig gered or an air‐
bag is deplo yed, you will hear a bang, and a
small amount of powder may also be released:
R The bang will not generally af fect your hear‐
ing. R
Ingeneral, the powder released is not haz‐
ardous tohealth but may cause short-term
breathing dif ficulties topersons suf fering
from as thma or other pulmonary conditions.
Pr ov ided it is safe todo so, lea vetheve hicle
immediately or open the window in order to
pr eve nt brea thing dif ficulties. Seat belts
Pr
otection pr ovided bythe seat belt Alw
aysfast enyour seat belt co rrectly before
st arting a journe y.A seat belt can only pr ovide
th e best le vel of pr otection if it is worncor rectly. &
WARNING Risk of inju ryor death due to
incor rectly fastened seat belt
If th e seat belt is not worncor rectly, it can‐
not per form its intended pr otective function.
In addition, an incor rectly fastened seat belt
can also cause injuries, forex ample, in the
ev ent of an accident or when braking or
ch anging direction sudden ly. #
Alwa ys ensure that all vehicle occu‐
pants ha vetheir seat belts fastened
cor rectly and are sitting prope rly. Alw
ays obser vethe instructions about the cor‐
re ct driver's seat position and adjusting the seat
(/ page 95).
In order forth e cor rectly wornseat belt topro‐
vide the intended le vel of pr otection, each vehi‐
cle occupant must obser vethefo llowing infor‐
mation:
R The seat belt must not be twis ted and must
fi t tightly and snu gly across the body.
R The seat belt must be routed across the
centre of the shoulder and as low down
across the hips as possible.
R The shoulder section of the seat belt should
not touch your ne cknor be routed under
yo ur arm or behind your bac k.
R Avoid wearing bulky clo thing, e.g. a winter
coat.
R Push the lap belt down as far as possible
across your hips and pull tight with the shoul‐ Occupant saf
ety39

der section of
the belt. Ne verro ute the lap
belt across your abdomen.
Pregnant women must also take particular
care with this.
R Neverro ute the seat belt across sharp, poin‐
te d, abrasive or fragile objects.
R Only one person should use each seat belt at
any one time. Ne ver allow babies and chil‐
dren totrave l sitting on the lap of ano ther
ve hicle occupant.
R Never secure objects with a seat belt if the
seat belt is also being used byone of the
ve hicle's occupants. Alw ays obser vethe
instructions for loading theve hicle when
securing objects, luggage or loads
(/ page 110).
Also ensure that no objects, e.g. a cushion,
are ever placed between a person and the
seat.
If ch ildren are tra velling in theve hicle, be sure to
obser vethe instructions and saf ety no tes on
"Children in theve hicle" (/ page54). Limitations of
the pr otection pr ovided bythe
seat belt &
WARNING Risk of inju ryor death due to
incor rect seat position
The seat belt will not of ferth e intended le vel
of pr otection if you ha venot mo vedth e seat
backrest toan almost vertical position.
In particular, you may slip under the seatbelt
and injure yourself. #
Adjust the seat proper lybefore begin‐
ning your journe y. #
Alw ays ensure that the seat backrest is
in an almost vertical position and that
th e shoulder section of your seat belt is
ro uted across the cent reofyour shoul‐
der. &
WARNING Risk of inju ryor death due to
an extended seat belt extender while the
ve hicle is in motion
If th e seat belt does not sit cor rectly on the
body, it cann otper form its intended pr otec‐
tive function. #
Alw ays ensure that the seat belt
ex tender is retracted while theve hicle
is in motion. If
th e seat belt extender does not retract au to‐
matically, it can be retracted manually. Todo so,
press the seat belt extender ba ckasfar as it will
go before starting theve hicle. Pressing the seat
belt extender ba ckinto place requ ires forc e. &
WARNING Risk of inju ryor death when
additional restra int sy stems are not used
fo r persons with a smaller stature
Pe rsons under 1.50 m tall cannot wearthe
seat belt cor rectly wi thout a suitable addi‐
tional restra int sy stem. 40
Occupant saf ety

#
Alw ays secure persons under 1.50 m
ta ll in a suitable restra int sy stem. &
WARNING Risk of inju ryor death due to
damaged or modified seat belts
Seat belts cann otprov ide pr otection in the
fo llowing situations:
R the seat belt is damaged, has been modi‐
fi ed, is extremely di rty, bleached or dyed
R the seat belt buckle is damaged or
ex treme lydirty
R modifications ha vebeen made tothe seat
belt tensioner, seat belt anchorage or
seat belt retractor
Seat belts may su stain non-visible damage in
an accident, e.g. due toglass splin ters.
Modified or damaged seat belts could tear or
fa il in theev ent of an accident, forex ample.
Modified seat belt tensioners could acciden‐
ta lly trigger or failto function as intended. #
Never modify the seat belt sy stem, for
ex ample the seat belt, seat belt buckle, seat belt
tensioner, seat belt anchorage
and seat belt retractor. #
Makesure that the seat belts are
undamaged, not wornand clean. #
Alw ays ha vethe seat belts checked
immediately af ter an accident at a
qu alified specialist workshop. Mercedes-Benz
recommends that you use seat
belts which ha vebeen appr ovedfo ryo ur vehicle
by Mercedes-Benz. &
WARNING Risk of inju ryor death from
deplo yedpy rotech nic seat belt tension‐
ers
Py rotech nic seat belt tensioners that ha ve
been deplo yed are no longer operational and
are unable toper form their intended pr otec‐
tive function. #
Therefore, ha vedeplo yedpy rotech nic
seat belt tensioners immedia tely
re placed at a qualified specialist work‐
shop. Mercedes-Benz
recommends that you ha vethe
ve hicle towe dto aqu alified specialist workshop
af te r an accident.
* NO
TEDama gecaused bytrapping the
seat belt If an unused seat belt is not fully
retracted, it
may become trapped in the door or in the
seat mechanism. #
Alw ays ensure that an unused seat belt
is fully retracted. Ex
tending/r etra cting the seat belt extender When
the door is closed, the seat belt extender
ex tends.
Yo u can also extend the seat-belt extender by
using theõ seat-belt extender button in the
centre console.
The õ seat belt extender button may also be
located in the switch panel abo vethe light
switch in Mercedes-AMG vehicles. #
Switch on the ignition. Occupant saf
ety41

#
Press theõ seat belt extender button.
The seat belt extender extends.
The seat belt extender retracts again in thefo l‐
lowing cases:
R the seat belt tongue is engaged in the seat
belt buckle
R the seat belt tongue is not engaged in the
seat belt buckle within 60 seconds
If yo u press theõ seat belt extender but‐
to n again in this case, the seat belt extender
will extend again.
R there spective door is opened
R youfo ld the seat backrest forw ards
R nobody is sitting in the front passenger seat
If yo u press theõ seat belt extender but‐
to n again in this case, the seat belt extender
will no longer extend.
The seat belt extender mu stalw ays be retracted
while theve hicle is in motion. Fa
stening seat belts If
th e seat belt is pulled quickly or sharpl y,the
seat belt retractor lo cks. The seat belt stra p can‐
not be pulled out any fur ther. #
Alw ays engage seat belt tongue 2ofthe
seat belt into seat belt buckle 1ofthe cor‐
re sponding seat. Ve
hicles with automatic front passen ger air‐
bag shu toff:
* NO
TEDeployment of the seat belt ten‐
sioner and side impact airbag when the
front passenger seat is unoccupied If
th e seat belt tongue is engaged in the seat
belt buckle of the unoccupied front
passenger seat, the seat belt tensioner and
th e side impact airbag may also deploy in the
ev ent of an accident along with other sys‐
te ms. #
Only one person should use each seat
belt at any one time. Ve
hicles without automatic front passen ger
airbag shu toff:
* NO
TEDeployment of the seat belt ten‐
sioner when the front passenger seat is
unoccupied If
th e seat belt tongue is engaged in the seat
belt buckle of the unoccupied front
passenger seat, the seat belt tensioner may 42
Occupant sa fety

also deploy in
theev ent of an accident along
with other sy stems. #
Only one person should use each seat
belt at any one time. Seat belt adjustment function
Ve
hicles with PRE-SAFE ®
:af te r a front seat
belt has been fastened, the automatic seat belt
adjustment may apply a cer tain tigh tening forc e.
Do not hold the seat belt tight lywhile it is
adjusting.
Yo u can activate and deactivate the seat belt
adjustment function using the multimedia sys‐
te m (/ page 43). Ac
tivating/deactivating seat belt adjustment
via the multimedia sy stem Multimedia sy
stem:
4 Vehicle 5
î Vehicle settings
5 Belt adjustment #
Activate Oor deacti vate ª the function. Re
leasing seat belts #
Press there lease button in the seat belt
buckle and guide the seat belt back with the
seat belt tongue. Seat belt
warning function for the driver and
front passen ger The
ü seat belt warning lamp in the instru‐
ment display is a reminder that all vehicle occu‐
pants must weartheir seat belts cor rectly.
In addition, a warning tone may sound.
As soon as the driver and front passenger fasten
th eir seat belts, the seat belt warning goes out. Fu
nction of there ar seat belt status display The
rear seat belt status display is on lyavailable
fo r cer tain countries. When
the ignition is switched on, there ar seat
belt status display informs youfo r a cer tain
amount of time which rear seat belt is not fas‐
te ned.
Yo u can immediately dismiss there ar seat belt
st atus display using the back button on the left-
hand side of thesteering wheel (/ page 228).
If a vehicle occupant unfas tens a seat belt in the
re ar while theve hicle is motion, there ar seat
belt status display appears again.
In addition, a warning tone may sound. In this
case, there ar seat belt status display cannot be
hidden using the back button on the left-hand
side of thesteering wheel. Occupant saf
ety43

Airbags
Overview of airbags
1
Knee airbag
2 Driver's airbag
3 Front passenger airbag
4 Head airbag
5 Side airbag
The ins tallation location of an airbag is identified
by the AIRB AGsymbol.
When enabled, an airbag can pr ovide additional
pr otection forth ere spective vehicle occupant. Pot
ential pr otection pr ovided byeach airbag:
R Knee airbag: thigh, knee and lo wer leg
R Driver's airbag, front passenger airbag: head
and ribcage
R Head airbag: head
R Side airbag: ribcage, also pelvis for front seat
occupants
* NO
TEMercedes-AMG vehicles #
Obser vethe no tes in the Supplement.
Yo u could otherwise failto recognise
dangers. &
WARNING Risk of inju ryor death if the
co-driver airbag is enabled
If th e co-driver airbag is enabled, a child on
th e co-driver seat may be stru ck bythe co-
driver airbag during an accident.
NEVER use a rear wa rd-facing child restra int
sy stem on a seat with an ENABLED FRONT
AIRB AG; DEAT H or SERIOUS INJU RYtothe
CH ILD can occur. When
fitting a child restra int sy stem tothe front
passenger seat, obser vetheve hicle-specific
information (/ page 69). Also, alw ays obser ve
th e no tes on rear wa rd-facing or forw ard-facing
ch ild restra int sy stems on the front passenger
seat.
Information on automatic front passenger
airbag shutoff
The front passenger airbag can only be deplo yed
in an accident if thePA SSENGER AIR BAG OFF
indicator lamp is off. If the front passenger seat
is occupied, make sure, bo thbefore and during
th e journe y,that thest atus of the front
passenger airbag is cor rect (/ page 49).
* NO
TEDeployment of components of the
re stra int sy stem when the front
passenger seat is unoccupied In an accident,
the components of the
re stra int sy stem may deploy unnecessarily
on the front passenger side if:
R There are heavy objects on the front
passenger seat. 44
Occupant saf ety

R
The seat belt tongue is engaged in the
seat belt buckle of the front passenger
seat and the front passenger seat is
unoccupied. #
Stow objects in a suitable place. #
Only one person should use each seat
belt at any one time. Depending on
the de tected accident situation,
th e head airbag on the front passenger side may
deplo y.The airbag is deplo yedre ga rdless of
whe ther the front passenger seat is occupied. Pr
otective capacity of the airbags Depending on
the accident situation, an airbag
may supplement the pr otection of fere dby a cor‐
re ctly fastened seat belt. &
WARNING Risk of inju ryor death due to
an incor rect seat position
If yo u deviate from the cor rect seat position,
th e airbag cann otper form its intended pro‐
te ctive function. Each
vehicle occupant must make sure of the
fo llowing:
R Fasten seat belts cor rectl y.Pregnant
wo men must take particular care to
ensure that the lap belt ne ver lies across
th e abdomen.
R Adopt the cor rect seat position and keep
as faraw ay as possible from the airbags.
R Obser vethefo llowing information. #
Alw ays make sure that there are no
objects between the airbag and vehicle
occupant. To
avo idtherisks resulting from the deployment
of an airbag, each vehicle occupant must
obser vethefo llowing information in particular:
R Before starting your journe y,adjust your seat
co rrectly; the driver's seat and front
passenger seat should be mo ved as far back
as possible.
When doing so, alw ays obser vethe informa‐
tion on the cor rect driver's seat position
(/ page 95). R
Only hold thesteering wheel bythesteering
wheel rim. This allows the airbag tobe fully
deplo yed.
R Alw ays lean against the seat backrest when
th eve hicle is in motion. Do not lean forw ards
or against the door or side windo w.You may
ot herwise be in the deployment area of the
airbags.
R The occupants must alw ayske ep their feet
on thefloor. Do not put your feet on the
cockpit, forex ample. Your feet may other‐
wise be in the deployment area of the airbag.
R Ifch ildren are tra velling in theve hicle,
obser vethe additional no tes (/ page54).
R Alwa ys stow and secure objects cor rectl y.
Objects in theve hicle interior may pr event an
airbag from functioning cor rectl y.Each vehicle
occupant must alw ays make sure of thefo llow‐
ing in particular:
R There are no people, animals or objects
between theve hicle occupants and an air‐
bag. Occupant saf
ety45

R
There are no objects between the seat, door
and door pillar (B-pillar).
R There are no hard objects, e.g. coat hangers,
hanging on the grab handles or coat hooks.
R There are no accessory parts, such as mobile
navigation devices, mobile phones or cup
holders, within the deployment area of an air‐
bag, e.g. on the cockpit, on the door, on the
side window or on the side trim.
In addition, no connecting cables, tensioning
st ra ps or retaining stra ps must be routed or
attached totheve hicle within the deploy‐
ment area of an airbag. Alw ays comply with
th e accessory manufacturer's ins tallation
instructions and, in particular, the no tes on
suitable places for ins tallation.
R There are no heavy, sharp-edged or fragile
objects in the poc kets of your clo thing. Store
such objects in a suitable place. Limited pr
otection pr ovided byairbags &
WARNING Risk of inju rydue tomodifi‐
cations tothe co ver of an airbag
If yo u modify the co ver of an airbag or af fix
objects such as sticke rs to it,the airbag may
no longer function cor rectl y. #
Never modify the co ver of an airbag and
do not af fix objects toit. The ins
tallation location of an airbag is identified
by the AIRB AGsymbol (/ page44). &
WARNING Risk of inju ryor death due to
th e use of unsuitable seat co vers
Due tounsuitable seat co vers,th e airbags
cann otprotect vehicle occupants as inten‐
ded.
In addition, the operation of the automatic
front passenger airbag shutoff could be
re stricted. #
You should on lyuse seat co vers that
ha ve been appr oved forth e cor respond‐
ing seats byMercedes-Benz. &
WARNING Risk of inju rydue tomalfunc‐
tioning sensors in the door
The function of the airbags can be impaired
due tomodifications or incor rect wo rkper‐
fo rm ed on the doors or door trim, or if the
doors are damaged. #
Never modify the doors or parts of the
doors. #
Alw ays ha vewo rkon the doors or door
trim car ried out at a qualified specialist
wo rkshop. &
WARNING Risk of inju rydue todeplo yed
airbag
A deplo yed airbag no longer of fers any pro‐
te ction. 46
Occupant saf ety

#
Have theve hicle towe dto aqu alified
specialist workshop in order tohave the
deplo yed airbag replaced. Ha
ve deplo yed airbags replaced immediately. St
atus of the front passenger front airbag Fu
nction of the automatic front passenger
airbag shu toff
The automatic front passenger airbag shutoff is
able todetect whe ther the front passenger seat
is occupied bya person or a child restra int sys‐
te m. The front passenger airbag is enabled or
disabled accordingly. &
WARNING Risk of inju ryor death due to
objects under the co-driver seat
Objects trapped under the co-driver seat can
inter fere with the function of the automatic
co-driver airbag shutoff or damage the sys‐
te m. #
Do not store any objects under the co-
driver seat. #
When the co-driver seat is occupied,
make sure that no objects are trapped
under the co-driver seat. When
fitting a child restra int sy stem tothe front
passenger seat, alw ays make sure of thefo llow‐
ing:
R Ensure that thech ild restra int sy stem is posi‐
tioned cor rectly (/ page 58).
R Alw ays comply with thech ild restra int sys‐
te m manufacturer's ins tallation instructions.
R Never place objects (e.g. cushions) under or
behind thech ild restra int sy stem.
R Fully retract the seat cushion length adjust‐
ment.
R The entire base of thech ild restra int sy stem
must alw aysre st on the sitting sur face of the
front passenger seat.
R The backrest of thefo rw ard-facing child
re stra int sy stem must, as far as possible, be
re sting on the seat backrest of the front
passenger seat. R
The child restra int sy stem must not touch the
ro of or be put under stra in by the head
re stra ints. Adjust the seat backrest inclina‐
tion and the head restra int setting accord‐
ing ly. &
WARNING Risk of inju ryor death due to
objects between the seat sur face and
th ech ild restra int sy stem
Objects between the sitting sur face and the
ch ild restra int sy stem could af fect the func‐
tion of the automatic co-driver airbag shut‐
off. #
Do not place any objects between the
sitting sur face and thech ild restra int
sy stem. #
The entire base of thech ild restra int
sy stem must alw aysre st on the sitting
sur face of the co-driver seat. #
The backrest of thefo rw ard-facing child
re stra int sy stem must, as far as possi‐
ble, be resting on the seat backrest of
th e co-driver seat. Occupant saf
ety47