ECU MERCEDES-BENZ C-CLASS COUPE 2021 Repair Manual

R
Mercedes-Benz emer gency call sy stem (auto‐
matic emer gency call and SOS button)
The Mercedes-Benz Cu stomer Centre and the
Mercedes-Benz emer gency call centre are availa‐
ble foryo u around the cloc k.
The me button and the SOS button can be found
on theve hicle's overhead control panel
(/ page 320).
Yo u can also call the Mercedes-Benz Cus tomer
Centre using the multimedia sy stem
(/ page 321).
Please no tethat Mercedes me connect is a
Mercedes-Benz service. In emer gencies, firs t call
th e national emer gency services using the
st andard national emer gency service telephone
numbers. In emer gencies, you can also use the
Mercedes-Benz emer gency call sy stem
(/ page 326).
Obser vethe conditions of use for Mercedes me
connect and other services. These can be
obtained in the Mercedes me Portal: https://
me.secure.mercedes-benz.com
Fu rther information about Mercedes me con‐
nect, the pr ovided service scope and operation: https://moba.i.daimler.com/mar
kets/ece-r ow/
baix/cars/connectme/en_GB/#emotions/
St artseite.html
Information on Mercedes me connect Acci‐
dent and Breakdown Management
The Accident and Breakdown Management can
include thefo llowing functions:
R Supplement tothe Mercedes-Benz emer‐
ge ncy call sy stem (/ page 326)
If necessar y,the conta ct person at the
Mercedes-Benz emer gency call centre for‐
wa rdsth e call toMercedes me connect Acci‐
dent and Breakdown Management. Forw ard‐
ing the call is ho wever not possible in all
countries.
R Breakdown assi stance byate ch nician on
location and/or theto wing away oftheve hi‐
cle tothe nearest Mercedes-Benz service
cent re
Yo u may be charge dfo rth ese services.
More information about Mercedes me connect
services can be obtained in the Mercedes me
Po rtal: https://me.secure.mercedes-benz.com Data trans
ferre d during Mercedes me con‐
nect call se rvices
The data transfer red during a Mercedes me con‐
nect call depends on:
R The reason for initiation of the call
R The service that is selec ted in thevo ice con‐
trol sy stem
R The activated Mercedes me connect services
Which data is transfer redfo rth e services can be
tak en from the cur rently valid term s of use.
These can be obtained in the Mercedes me por‐
tal : https://me.secu re.mercedes-benz.com Mercedes-Benz eme
rgency call sy stem Information on
the Mercedes-Benz emer‐
ge ncy call sy stem
The Mercedes-Benz emer gency call sy stem only
functions in areas where mobile phone co verage
is available from the mobile phone network pro‐
viders. Insuf ficient network co verage from the
mobile phone network pr oviders may result in an
emer gency call not being transmitted. Multimedia sy
stem 325

Setting up
thewa rning triangle #
Fold side reflectors 1upwards toform a tri‐
angle and attach at theto p using upper
press-stud 2. #
Fold legs 3down and out tothe side. Fi
rs t-aid kit (soft-sided) overview Fir
st-aid kit (so ftsided) 1is in the boot in the
left-hand or right-hand stowage net, depending
on the model. Re
moving the fire extinguisher &
WARNING Risk of accident due toan
incor rectly secu redfire extinguisher in
th e driver's foot we ll
A fire extinguisher may impede pedal tr avel
or block a depressed pedal.
This jeopardises the operating and road
saf ety of theve hicle.
The fire extinguisher can be flung around and
injure the driver or other vehicle occupants. #
Alw aysst ore and secure thefire extin‐
guisher in the brac ket. #
Do not remo vethefire extinguisher
while driving. Breakdown assi
stance 377

If
th e indicator/warning lamps in the instrument
clus ter do not light up at low temp eratures, it is
ve ry likely that the dischar ged battery has fro‐
zen. In this case you may neither jump-s tart the
ve hicle nor charge the batter y.
The service life of a battery that has been
th awe d may be dramatically shor tened. The
st arting characteristics may be impaired, espe‐
cially at low temp eratures.
It is recommended that you ha veathaw ed bat‐
te ry checked at a qualified specialist workshop.
All vehicles
* NO
TEDama gecaused bynumerous or
ex tended attem ptsto start the engine Nume
rous or extended attem ptsto start the
engine may damage the catalytic con verter
due tonon-combu sted fuel. #
Avoid numerous and extended attem pts
to start the engine. Obser
vethefo llowing points during starting
assis tance and when charging the battery:
R Only use undamaged jump lead/charging
cables with a suf ficient cross-section and
insula tedte rm inal clamps.
R Non- insulated parts of thete rm inal clamps
must not come into con tact wi thother me tal
parts while the jump lead/charging cable is
connected tothe battery/jump-s tart connec‐
tion point.
R The jump lead/charging cable must not
come into contact wi thany parts which may
mo vewhen the engine is running.
R Alw ays make sure that nei ther you nor the
battery is elect rostatically charge d.
R Keep away from fire and naked flames.
R Do not lean overth e batter y.
Obser vethe additional following points when
ch arging the battery:
R Only use battery charge rs tested and
appr oved for Mercedes-Benz.
R Read the battery charge r's operating instruc‐
tions before charging the batter y. Obser
vethe additional following points during
st arting assis tance:
R Starting assis tance may only be pr ovided
using vehicles, batteries or other jump start
devices with a nominal voltage of 12V.
R The vehicles must not touch.
R Vehicles with a petrol engine: jump-start
th eve hicle only when the engine and exhaust
sy stem are cold. St
arting assi stance and charging the12 V
battery Preparing
starting assi stance/charging #
Secure theve hicle byapplying the electric
parking brake. #
Automatic transmission: shiftthe trans‐
mission toposition j. #
Manual transmission: shiftthe transmis‐
sion toneutral. #
Switch off the ignition and all electrical con‐
sumers. #
Open the bonn et. 388
Breakdown assis tance

&
WARNING Risk of accident due tolimi‐
te d saf ety-re lated functions during the
to wing process
Saf ety-re lated functions are limited or no lon‐
ge rav ailable in thefo llowing situations:
R the ignition is switched off.
R the brake sy stem or po werst eering sys‐
te m is malfunctioning.
R the energy supply or the on-board electri‐
cal sy stem is malfunctioning.
When your vehicle is then towe daw ay, signif‐
icantly more ef fort may be requ ired tosteer
and brake than is no rmally requ ired. #
Use a tow bar. #
Make sure that thesteering wheel can
mo vefreely before towing theve hicle
aw ay. *
NO
TEDama gedue toexcessive tracti ve
po wer If
yo u pull away sharpl y,the tractive po wer
may be too high and theve hicles could be
damaged. #
Pull away slowly and smoo thly. Loading the
vehicle for transport #
Obser vethe no tes on towing away
( / page 391). #
Connect theto w bar totheto wing eye in
order toload theve hicle.
% You can also attach theto w bar tothe trailer
hitch. #
Vehicles with automatic transmission:
shift the automatic transmission toposition
i.
% Ve
hicles with automatic transmission:
th e automatic transmission may be loc ked in
position jintheeve nt of dama getothe
electrical sy stem. Toshift toi , pr ovide the on-board electrical sy
stem with po wer
( / page 388). #
Load theve hicle onto the transpor ter. #
Vehicles with automatic transmission:
shift the automatic transmission toposition
j. #
Use the electric parking brake tosecure the
ve hicle against rolling away. #
Only secure theve hicle bythe wheels.
Ve hicles with ADS PLUS (Adaptive Damping
Sy stem PLUS) &
WARNING Risk of an accident when
transporting vehicles with Adaptive
Damping Sy stem PLUS
When transporting vehicles with Adaptive
Damping Sy stem PLUS, theve hicle/trailer
combination may begin torock andstart to
skid. #
When transporting, ensure that:
R theve hicle has been loaded onto
th e transpor ter cor rectly Breakdown assis
tance 393

R
theve hicle is secured at all four
wheels with suitable tensioning
st ra ps
R the maximum permissible speed of
60 km/h is not exceeded when
transporting *
NO
TEDama getotheve hicle from secur‐
ing it incor rectly #
After loading, theve hicle must be
secured on all four wheels. Otherwise,
th eve hicle could be damaged. #
A minimum dis tance of 20 cm up wards
and 10cm down wards must be kept to
th e transport platform. #
Secure theve hicle on all four wheels af ter
loading. 4MATIC
vehicles/ vehicles with automatic
transmission #
Make sure that the front and rear axles come
to rest on the same transpor tation vehicle.
* NO
TEDama getothe driv etra in due to
incor rect positioning #
Do not position theve hicle abo vethe
connection point of the transport vehi‐
cle. To
wing eyesto rage location To
wing eye1 is in a brac ket under there ar
shelf. 394
Breakdown assis tance

amperage,
the electric line could be overloa‐
ded.
This could result in a fire. #
Alw aysre place faulty fuses with speci‐
fi ed new fuses conta iningthe cor rect
amperage. *
NO
TEDama gedue toincor rect fuses Electrical components or sy
stems may be
damaged byincor rect fuses, or their func‐
tionality may be significant lyimpaired. #
Only use fuses that ha vebeen appr oved
by Mercedes-Benz and which ha vethe
cor rect fuse rating. Blown fuses mu
stbe replaced with fuses of the
same rating, which you can recognise bythe col‐
our and the label. The fuse ratings and fu rther
information tobe obser ved can be found in the
fuse assignment diagram.
Fu se assignment diag ram: onthe fuse box in
th e boot (/ page 398). *
NO
TEDama geor malfunctions caused
by moisture Moisture may cause dama
getothe electrical
sy stem or cause it tomalfunction. #
When the fuse box is open, make sure
th at no moisture can enter the fuse
box. #
When closing the fuse box, make sure
th at the seal of the lid is positioned cor‐
re ctly on the fuse box. If
th e newly inser ted fuse also blo ws, ha vethe
cause traced and rectified at a qualified special‐
ist workshop.
Ensure thefo llowing before replacing a fuse:
R The vehicle is secured against rolling away.
R All electrical consumers are switched off.
R The ignition is switched off.
The electrical fuses are located in various fuse
bo xes:
R Fuse box in the engine compartment on the
driver's side (/ page 396) R
Fuse box on the driver's side of the cockpit
(/ page 397)
R Fuse box in the front passenger foot we ll
(/ page 398)
R Fuse box in the boot on theright-hand side
of theve hicle, when vie wed in the direction
of tr avel (/ page 398) Opening and closing
the fuse box in the
engine compa rtment Requ
irements:
R A dry clo thand a sc rewdriver are available.
Obse rveth e no tes on electrical fuses
(/ page 395).
Opening &
WARNING Risk of inju ryfrom using the
windscreen wipers while the engine bon‐
net is open
When the engine bonn etis open, and the
windscreen wipers are set in motion, you can
be trapped bythe wiper linkage. 396
Breakdown assis tance

shop. The new wheel must ha
vethe
cor rect dimensions. %
The emergency spa rewheel is secured in the
emer gency spa rewheel bag in the boot.
Obser vethefo llowing no tes on fitting an emer‐
ge ncy spa rewheel:
R Check the tyre pressure of the emer gency
spa rewheel fitted. Co rrect the pressure as
necessar y.
R The maximum permissible speed with an
emer gency spa rewheel fitted is 80 km/h.
R Do not fit th e emer gency spa rewheel with
sn ow ch ains.
R Replace the emer gency spa rewheel af ter six
ye ars at the latest, rega rdless of wear.
% Ve
hicles with a tyre pressure loss warn‐
ing sy stem: if an emer gency spa rewheel is
fi tted, the tyre pressure loss warning sy stem
cann otfunction reliabl y.Only restart the sys‐
te m again when the emer gency spa rewheel
has been replaced with a new wheel. Ve
hicles with a tyre pressure monitoring
sy stem: if an emer gency spa rewheel is fit‐
te d, the tyre pressure monitoring sy stem
cann otfunction reliabl y.Fo r a few minutes
af te r an emer gency spa rewheel is fitted, the
sy stem may still display the tyre pressure of
th ere mo ved wheel. Only restart the sy stem
again when the emer gency spa rewheel has
been replaced with a new wheel.
Be sure toalso obse rveth efo llowing fur ther
re lated subjects:
R Notes on tyre pressure (/ page 400)
R Tyre pressure table (/ page 401)
R Notes on fitting tyres (/ page 404) Wheels and tyres
415

Display messages
Possible causes/consequences and M
MSolutions &
WARNING Risk of inju ryor death when using a child restra int sy stem while the front passenger airbag is
enabled
If yo u secure a child in a child restra int sy stem on the front passenger seat and the front passenger airbag is
enabled, the front passenger airbag can deploy in theeve nt of an accident.
The child could be stru ck bythe airbag. #
Ensure, bo thbefore and during the journe y,that thest atus of the front passenger airbag is cor rect.
NEVER use a rear wa rdfacing child restra int on a seat pr otected byan ACTIVE AIRB AGin front of it, DE ATH or
SERIOUS INJU RYtotheCH ILD can occur. #
Stop theve hicle immediately in accordance with the traf fic conditions. #
Makesure that no objects are trapped under the front passenger seat. #
Check thest atus of automatic front passenger airbag actuation (/ page 49).#
If necessar y,consult a qualified specialist workshop immediatel y.
PRE-SAFE inoperative See
Owner's Manual *
The PRE‑SAFE ®
functions are malfunctioning. #
Consult a qualified specialist workshop. 436
Display messages and warning/indicator lamps

Ve
hicle Display messages
Possible causes/consequences and M
MSolutions
d Vehicle is operational
Switch off ignition before
exiting *Y
ou are leaving theve hicle in a ready-to-drive state. #
When you lea vetheve hicle, switch off the ignition, secure theve hicle against rolling away and take theke y with
yo u. #
Ifyo u do not lea vetheve hicle, switch off the electrical consumers, e.g. the seat heating. Otherwise, the12 ‑V
battery may discharge and starting the engine may be possible only with the help of a second battery (jump
st art).
ï
Check trailer hitch lock *T
he trailer hitch is not operational during a journey with a trailer. &
WARNING Risk of an accident if the ball neck is not loc ked
The trailer may become de tach ed. #
Stop theve hicle immediately in accordance with the traf fic conditions. Do not continue driving. #
Uncouple the trailer and secure it against rolling away. #
Initiate a new swivel mo vement and do not re-couple the trailer until thewa rning/indicator lamp goes out. #
Initiate a new swivel mo vement (/ page 227). #
When the display message disappears, couple up the trailer and drive on.
If th e display message does not disappear, the trailer hitch is malfunctioning and the ball neck is not loc ked. Display messages and
warning/indicator lamps 443

Display messages
Possible causes/consequences and M
MSolutions #
Do not couple up the trailer. Drive on without the trailer. No tethere duced ground clearance due tothe
unlo cked ball nec k. #
Consult a qualified specialist workshop.
*T he trailer hitch will not be operational when theve hicle is stationar y. #
Uncouple the coupled trailer and secure it against rolling away. #
Ifth e ball neck has been folded in: unlockthe ball neck (/ page 227). #
Swivel the ball neck into the end position manually and let it engage. #
Ifth e ball neck has been folded out: unlockthe ball neck (/ page 227). #
Swivel the ball neck beneath the bumper manually and let it engage.
If th e display message does not disappear, the trailer hitch is malfunctioning and the ball neck is not loc ked. #
Do not couple up the trailer. Drive on without the trailer. No tethere duced ground clearance due tothe
unlo cked ball nec k. #
Consult a qualified specialist workshop.
Ù Steering malfunction
Increased physical effort
See Owner's Manual *T
he po werst eering assis tance is malfunctioning. &
WARNING Risk of an accident due toaltered steering characteristics
If th e po wer assi stance of thesteering fails partially or comple tely, you will need touse more forc eto steer. #
If safe steering is possible, drive on carefully. 444
Displaymessa ges and warning/indicator lamps