ECU MERCEDES-BENZ C-CLASS CABRIOLET 2021 Owners Manual

&
WARNING Risk of accident due tocon‐
necting devices tothe diagnostics con‐
nection
If yo u connect devices tothe diagnostics
connection of theve hicle, the function of
ve hicle sy stems and operating saf ety may be
impaired. #
For saf etyre asons, werecommend that
yo u on lyuse and connect products
appr ovedby yo ur Mercedes-Benz
service centre. &
WARNING Risk of accident due to
objects in the driver's foot we ll
Objects in the driver's foot we ll may impede
pedal tr avel or block a depressed pedal.
This jeopardises the operating and road
saf ety of theve hicle. #
Stow all objects in theve hicle securely
so that they cannot getinto the driver's
fo ot we ll. #
Alw aysfit th efloor mats securely and
as prescribed in order toensure that th
ere is alw ays suf ficient room forthe
pedals. #
Do not use loose floor mats and do not
place floor mats on top of one ano ther. *
NO
TEBattery discharging from using
devices connected tothe diagnostics
connection Using devices at
the diagnostics connection
drains the batter y. #
Check thech arge leve l of the batter y. #
Ifth ech arge leve l is lo w,charge the
batter y,e.g. bydriving a considerable
dis tance. Please also no
tethe information about the12 V
battery and short-dis tance trips in the "Driving
and Parking" chap ter (/ page142). Connecting and using ano
ther device with the
diagnostics connection can ha vethefo llowing
ef fects:
R malfunctions in theve hicle sy stem
R permanent damage tovehicle components
Please referto thewa rranty term s and condi‐
tions forth is matter. 30
General no tes

Depending on
theve hicle equipment, this
includes thefo llowing data, forex ample:
R multimedia data, such as music, films or pho‐
to sfo r playback in an integrated multimedia
sy stem
R address book data for use in connection with
an integrated hands-free sy stem or an inte‐
grated navigation sy stem
R entered navigation destinations
R data about the use of Internet services
These data for con venience and inf otainment
functions may be sa ved locally in theve hicle or
th ey may be located on a device which you ha ve
connected totheve hicle, such as a smartphone,
USB flash drive or MP3 pla yer.If yo u ha ve
entered these data yourself, you can dele tethem
at any time.
This data is transmit ted from theve hicle tothird
parties only at your requ est. This applies, in par‐
ticular, when you use online services in accord‐
ance with the settings that you ha veselected. Smartphone integ
ration (e.g. Android Autoor
Apple CarPlay ®
)
If yo ur vehicle is accordingly equipped, you can
connect your smartphone or ano ther mobile end
device totheve hicle. You can then control them
by means of the control elements integrated in
th eve hicle. Images and audio from the smart‐
phone can be output via the multimedia sy stem.
Cer tain information is simultaneously transfer‐
re dto yo ur smartphone. Depending on the type
and integration, this includes position data, day/
night mode and other general vehicle statuses.
Fo r more information please consult the Owner's
Manual of theve hicle/inf otainment sy stem.
This integration allo ws the use of selected
smartphone apps, such as navigation or music
pla yer apps. There is no fur ther interaction
between the smartphone and theve hicle; in par‐
ticular, vehicle data is not directly accessible.
The type of additional data processing is de ter‐
mined bythe pr ovider of the app being used.
Which settings you can make, if an y,depends on
th e specific app and the operating sy stem of
yo ur smartphone. Online services
Wire
less network connection
If yo ur vehicle has a wireless network connec‐
tion, it enables data tobe exc hanged between
yo ur vehicle and additional sy stems. The wire‐
less network connection is made possible bythe
ve hicle's own transmitter and recei ver or by a
mobile end device that you ha vebrought into the
ve hicle, forex ample, a smartphone. Online func‐
tions can be used via the wireless network con‐
nection. This includes online services and appli‐
cations/apps pr ovided to yo uby the manufac‐
turer or by other pr oviders.
Manu factu rer's se rvices
Re garding the manufacturer's online services,
th e individual functions are described bythe
manufacturer in a suita ble place,forex ample, in
th e Owner's Manual or on the manufacturer's
we bsite, where there leva nt da taprotection
information is also given. Personal data may be
used forth e pr ovision of online services. Data
are exchanged via a secure connection, such as
th e manufacturer's designated IT sy stems. Any
personal data which are collected, processed General no
tes35

Re
stra int sy stem Pr
otection pr ovided bythere stra int sy stem The
restra int sy stem includes thefo llowing com‐
ponents:
R Seat belt sy stem
R Airbags
R Child restra int sy stem
R Child seat securing sy stems
The restra int sy stem can help pr eventtheve hi‐
cle occupants from coming into contact with
parts of theve hicle interior in theev ent of an
accident. In theev ent of an accident, the
re stra int sy stem can also reduce thefo rc es to
which theve hicle occupants are subjected.
A seat belt can only pr ovide the best le vel of pro‐
te ction if it is worncor rectl y.Depending on the
de tected accident situation, seat belt tensioners
and/or airbags supplement the pr otection
of fere dby a cor rectly wornseat belt. Seat belt
te nsioners and/or airbags are not depl oyed in
eve ryaccident. In order
forth ere stra int sy stem toprov ide the
intended le vel of pr otection, each vehicle occu‐
pant must obser vethefo llowing information:
R Fasten seat belts cor rectl y.
R Sit in an almost up right seat position with
th eir back against the seat backrest.
R Sit with their feet resting on thefloor, if pos‐
sible.
R Alw ays secure persons under 1.50 m tall in
an additional restra int sy stem suitable for
Mercedes-Benz vehicles.
Ho wever,no sy stem available today can com‐
ple tely elimin ate injuries and fata lities in every
accident situation. In particular, the seat belt
and airbag generally do not pr otect against
objects penetrating theve hicle from the outside.
It is also not possible tocompl etely rule out the
ri sk of injury caused bythe airbag deploying. Re
duced restra int sy stem pr otection &
WARNING Risk of inju ryor death due to
modifications tothere stra int sy stem
Ve hicle occupants may no longer be pr otec‐
te d as intended if alterations are made tothe
re stra int sy stem. #
Never alter the parts of there stra int
sy stem. #
Neverta mp er with the wiring or any
electronic component parts or their
software. If it is necessary
tomodify theve hicle toaccom‐
modate a person with disabilities, con tact a
qu alified specialist workshop.
Mercedes-Benz recommends that you use driv‐
ing aids which ha vebeen appr ovedfo ryo ur vehi‐
cle byMercedes-Benz. Re
stra int sy stem functionality When
the ignition is switched on, a self-test is
per form ed, during which the6 restra int sys‐ Occupant saf
ety37

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

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

&
WARNING Risk of inju ryor death when
using a rear wa rd-facing child restra int
sy stem while the front passenger airbag
is enabled
If yo u secure a child in a rear wa rd-facing
ch ild restra int sy stem on the front passenger
seat and thePA SSENGER AIR BAG OFF indi‐
cator lamp is off, the front passenger airbag
can deploy in theev ent of an accident.
The child could be stru ck bythe airbag.
Alw ays ensure that the front passenger air‐
bag is disabled. The PASSENGER AIR BAG
OFF indicator lamp must be lit.
NEVER use a rear wa rd-facing child restra int
sy stem on a seat with an ENABLED FRONT
AIRB AG. This can result in the DEAT H of or
SERIOUS INJU RYtotheCH ILD. When
fitting a child restra int sy stem tothe front
passenger seat, obser vetheve hicle-specific
information (/ page 69).
Depending on thech ild restra int sy stem and the
st ature of thech ild, thePA SSENGER AIR BAG
OFF indicator lamp may be off. In this case, do not
fit th ere ar wa rd-facing child restra int sy stem
to the front passenger seat.
Ins tead, fit th ere ar wa rd-facing child restra int
sy stem toa suitable rear seat.
Af terfitting a forw ard-facing child restra int
sy stem tothe front passenger seat: depend‐
ing on thech ild restra int sy stem and thest ature
of thech ild, PASSENGER AIR BAG OFF may be lit
continuously or be off. Alw ays obser vethefo l‐
lowing information. &
WARNING Risk of inju ryor death due to
incor rect positioning of thefo rw ard-
fa cing child restra int sy stem
If yo u secure a child in a forw ard-facing child
re stra int sy stem on the front passenger seat
th at is positioned too close tothe cockpit, in
th eev ent of an accident, thech ild could:
R come into con tact wi thparts of theve hi‐
cle's interior if thePA SSENGER AIR BAG
OFF indicator lamp is lit, forex ample
R bestru ck bythe airbag if thePA SSENGER
AIR BAG OFF indicator lamp is off #
Alw ays mo vethe front passenger seat
as far back as possible and fully retract
th e seat cushion length adjustment.
While doing so, alw ays make sure that
th e shoulder belt stra p is cor rectly
ro uted from the seat belt outlet of the
ve hicle tothe shoulder belt guide on
th ech ild restra int sy stem. The shoulder
belt stra p must be routed forw ards and
down wards from the seat belt outlet. If
necessar y,adjust the front passenger
seat accordingly. #
Alw ays comply with thech ild restra int
sy stem manufacturer's ins tallation
instructions. When
fitting a child restra int sy stem tothe front
passenger seat, obser vetheve hicle-specific
information (/ page 69).
If a person is sitting on the front passenger
seat: PASSENGER AIR BAG OFF may be lit con‐
tinuously or be off, depending on the person's
st ature. 50
Occupant saf ety

&
WARNING Danger of inju ryor death due
to obstructed roll bars
If yo u lea veobjects or items of clo thing on
th e co vers of thero ll bars, thero ll bars can‐
not pr otect as intended.
Fu rthermore, the objects may endanger vehi‐
cle occupants when thero ll bars extend. #
Alw ays make sure that theth ere is
no thing in the sweep of thero ll bars. #
Alw aysstow and secure objects in the
ve hicle cor rectl y. The
roll bars are under the co vers behind the
re ar head restra ints. The roll bars are triggered
when danger of theve hicle rolling over is de tec‐
te d.
Once thero ll bars ha vebeen triggered, you can
no lon ger close a soft topth at is open. In this
case, consult the next qualified specialist work‐
shop. PRE-SAFE
®
sy stem PRE-
SAFE®
(anticipa tory occupant pr otec‐
tion) PRE-
SAFE®
is able todetect cer tain critical driv‐
ing situations and implement pre-em ptive meas‐
ures toprotect theve hicle occupants.
PRE-SAFE ®
can implement thefo llowing meas‐
ures independently of each other:
R Tightening the seat belts on the driver's seat
and front passenger seat.
R Closing the side windo ws. R
Vehicles with memory function: movethe
front passenger seat toa more favo urable
seat position.
R Vehicles with multicontour seat: increase
th e air pressure in the seat side bols ters of
th e seat backrest.
R PRE-SAFE ®
Sound: pr ovided that the multi‐
media sy stem is switched on, generates a
brief noise signal tostimulate the innate pro‐
te ctive mechanism of a person's hea ring.
* NO
TEDama gecaused byobjects in the
fo ot we ll or behind the seat The automatic adjustment of
the seat posi‐
tion may result in damage tothe seat and/or
th e object. #
Stow objects in a suitable place. Re
versing the PRE- SAFE®
sy stem measures If an accident did not occur,
the pre-em ptive
measures that we retak en are reve rsed. 52
Occupant saf ety

Yo
u will need toper form certain settings your‐
self. #
Ifth e seat belt pre-tensioning is not reduced,
mo vethe seat backrest back slightl y.
The locking mechanism releases. Fu
nction of PRE-SAFE ®
PLUS (anticipatory
occupant pr otection plus) PRE-
SAFE®
PLUS can de tect cer tain impacts,
particular lyan imminent rear impact, and take
pre-em ptive measures toprotect theve hicle
occupants. These measures cannot necessarily
pr eve nt an imminent impact.
PRE-SAFE ®
PLUS can implement thefo llowing
measures independently of each other:
R Tightening the seat belts on the driver's seat
and front passenger seat.
R Activating there ar hazard warning lights at a
higher flashing frequenc y.
R Increasing brake pressure when theve hicle
is stationar y.This brake application is cancel‐
led automatically when theve hicle pulls
aw ay. If an accident did not occur,
the pre-em ptive
measures that we retake n are reve rsed.
Sy stem limits
The sy stem will not initiate any action in thefo l‐
lowing situations:
R when reve rsing
or
R when theve hicle is towing a trailer and there
is a risk of a rear impact
The sy stem will not initiate any braking applica‐
tion in thefo llowing situations:
R whilst driving
or
R when entering or exiting a parking space
while using Active Parking Assist Safely transporting
children in theve hicle Alw
ays obser vewhen children are tr avelling
in theve hicle %
Also strictly obser vethe saf ety no tesfo rthe
specific situation. In this wa yyo u can recog‐ nise po
tential risks and avoid dangers if chil‐
dren are tr avelling in theve hicle
(/ page 54).
Be diligent
Bear in mind that negligence when securing a
ch ild in thech ild restra int sy stem may ha veseri‐
ous consequences. Alw ays be diligent in secur‐
ing a child carefully before everyjou rney.
To impr oveprotection forch ildren younger than
12 years old or under 1.50 m in height,
Mercedes-Benz recommends you obse rvethe
fo llowing information:
R Alw ays secure thech ild in a child restra int
sy stem suitable forth is Mercedes-Benz vehi‐
cle.
R The child restra int sy stem must be appropri‐
ate tothe age, weight and size of thech ild.
R The vehicle seat must be suitable forfitting a
ch ild restra int sy stem (/ page 58).
Ac cident statistics show that children secured
on there ar seats are general lysafer than chil‐
dren secured on the front seats. Forth is reason, Occupant saf
ety53

Mercedes-Benz
stronglyadvises that youfit a
ch ild restra int sy stem toare ar seat.
The generic term ch ildrestra int sy stem
The generic term child restra int sy stem is used
in this Owner's Manual. A child restra int sy stem
is, forex ample:
R a baby car seat
R are ar wa rd-facing child seat
R afo rw ard-facing child seat
R ach ild boos ter seat with a backrest and seat
belt guide
Mercedes-Benz recommends using a child
boos ter seat with a backrest.
The child restra int sy stem must be appropriate
to the age, weight and size of thech ild.
Obser velaws and legal requ irements
Alw ays obser vethe legal requirements when
using a child restra int sy stem in theve hicle.
Make sure that thech ild restra int sy stem is
appr oved in accordance with theva lid test speci‐
fi cations and guidelines. Further information can
be obtained at a qualified specialist workshop. Mercedes-Benz
recommends that you use a
Mercedes-Benz Service Centre forth is purpose.
Only use appr oved child restra int sy stems
Only child restra int sy stems that meet thefo l‐
lowing UNECE standards are permit tedfo r use in
th eve hicle:
R UN-R44
R UN-R129 (i-Size child restra int sy stems)
Information on child restra int sy stem appr oval
categories and de tails on the appr oval label on
th ech ild restra int sy stem (/ page 58). De
tecting risks, avoiding dan ger Securing sy
stems forch ild restra int sy stems
in theve hicle
Only use thefo llowing securing sy stems forch ild
re stra int sy stems:
R the ISOFIX or i-Size securing rings
R theve hicle's seat belt sy stem
R theTo pTe ther anchorages Fitting an ISOFIX or an i-Size
child restra int sys‐
te m is prefer red.
Simply attaching tothe securing rings on the
ve hicle can reduce therisk of fitting thech ild
re stra int sy stem incor rectly.
When secu ring a child with the integrated seat
belt of the ISOFIX or i-Size child restra int sys‐
te m, alw ays comply with the permissible gross
we ight forth ech ild and child restra int sy stem
(/ page 62).
Ad vantage of a rear wa rd-facing child
re stra int sy stem
It is preferable totranspo rta baby or a small
ch ild in a suitable rear wa rd-facing child restra int
sy stem. In this case, thech ild sits in the oppo‐
site direction tothe direction of tr avel and faces
ba ckwa rds.
Babies and small children ha vecompa ratively
we ak neck muscles in relation tothe size and
we ight of their head. The risk of injury tothe cer‐
vical spine during an accident can be reduced in
a re ar wa rd-facing child restra int sy stem. 54
Occupant saf ety