warning light MERCEDES-BENZ A-CLASS HATCHBACK 2021 Service Manual

F
F
unction of B
unction of B AS
AS &
W
WARNING
ARNING Risk of an accident caused by a
malfunction in BAS(Brake Assist System)
If BAS is malfunctioning, the braking distance
in an emer gency braking situation is
increased. #
Dep ress the brake pedal with full forc e in
emer gency braking situations. ABS pre-
ve nts the wheels from locking. The Brake Assist System (BAS) supports
your
emer gency braking situation with additional brake
fo rc e.
If yo u depress the brake pedal quickl y,BAS is
activated:
R BAS automatically boosts the brake pressure.
R BAS can shor tenth e braking distance.
R ABS pr events the wheels from locking.
The brakes will function as usual once youre lease
th e brake pedal. BASis deactivated. F
F
unctions of ESP
unctions of ESP ®
® &
W
W ARNING
ARNING Risk of skidding if ESP ®
is
deactivated
If yo u deactivate ESP ®
, ESP ®
cannot car ryout
ve hicle stabilisation. #
ESP ®
should only be deactivated in the
fo llowing situations. *
N
NOOTE
TE Mercedes-AMG vehicles #
Obser vethe no tes in the Supplement.
Yo u could otherwise failto recognise
dangers. The Electronic
Stability Prog ram (ESP ®
) can moni-
to r and impr ove driving stability and traction in
th efo llowing situations within ph ysical limits:
R When pulling away on wet or slippery car riage-
ways.
R When braking. If
th eve hicle deviates from the direction desired
by the driver, ESP ®
can stabilise theve hicle by
inter vening in thefo llowing ways:
R One or more wheels are braked.
R The engine output is adap ted according tothe
situation.
ESP ®
is deacti vated if theå ESP®
OFF warn-
ing lamp lights up continuously in the instrument
cluster.
Obser vethefo llowing points when ESP ®
is deacti-
va ted:
R Driving stability will no longer be impr oved.
R The drive wheels could spin.
R ETS/4ETS traction control is still active.
% When ESP ®
is deactivated, you are still assis-
te dby ESP ®
when braking.
If th e÷ ESP®
wa rning lamp 0ashes in the
inst rument cluster, one or se veral wheels has
re ached its grip limit:
R Adapt the driving style tosuit the pr evailing
ro ad and weather conditions. 222 222
Driving and parking

R
Do not deactivate ESP ®
under any circumstan-
ces.
R Only depress the accelerator pedal as far as is
necessar y.
It may be best todeactivate ESP ®
in thefo llowing
situations:
R When using snow chains.
R In deep sno w.
R On sand or grav el.
% Spinning the wheels results in a cutting
action, which enhances traction.
If th e÷ ESP®
wa rning lamp lights up continu-
ousl y,ESP ®
is not available due toa malfunction.
Obser vethefo llowing information:
R Warning and indicator lamps (/ page 476)
R Display message s (/page 409)
ET
ET S/4ET
S/4ET S (Electr
S (Electr onicTr
onic Traction Syst
action Syst em)
em)
ETS/4ETS traction cont rol is part of ESP ®
and
makes it possible topull away and accelerate on a
slippery car riag ewa y. ETS/4ETS can impr
ovetheve hicle's traction by
inter vening in thefo llowing ways:
R The drive wheels are braked individually if they
spin.
R More drive torque is tr ansferredto the wheel
or wheels with traction.
In0uence
In0uence of dr
of driv
ive pr
e pr ogr
ograms on ESP
ams on ESP ®
®
The drive prog rams enable ESP ®
to adapt todif-
fe re nt we ather and road conditions as well as the
driver's prefer red driving style. Depending on the
selected drive prog ram, the appropriate ESP ®
mode will be activated. You can select the drive
prog rams using theDY NAMIC SELECT switch
(/ page 179). F
F
unction of ESP
unction of ESP ®
®
Cr
Cr osswind Assist
osswind Assist ESP
®
Crosswind Assist de tects sudden gusts of
side wind and helps the driver tokeep theve hicle
in the lane:
R ESP ®
Crosswind Assist is active at vehicle
speeds between appr ox. 75 km/h and
200 km/h when driving straight ahead or cor-
nering slightl y. R
The vehicle is stabilised bymeans of individual
brake application on one side. F F
unction of ESP
unction of ESP ®
®
tr
trailer st
ailer st abilisation
abilisation &
W WARNING ARNING Risk of accident in poor road
and weather conditions
In poor road and weather conditions, the
trailer stabilisation cannot pr event lur ching of
th eve hicle/trailer combination. Trailers with a
high cent reofgrav ity may tip over before
ESP ®
de tects this. #
Always adapt your driving style tosuit
th e cur rent road and weather conditions. When driving with a trailer, ESP
®
can stabilise
yo ur vehicle if the trailer begins toswer vefrom
side toside:
R ESP ®
trailer stabilisation is active abo ve
speeds of 65 km/h.
R Slight swerving is reduced bymeans of a tar-
ge ted, individual brake application on one
side. Driving and parking
223
223

R
Intheev ent of se vere swerving, the engine
output is also reduced and all wheels are
braked.
ESP ®
trailer stabilisation may be impaired or may
not function if:
R The trailer is not connected cor rectly or is not
de tected proper lyby theve hicle. A
A
ctiv
ctiv ating/deactiv
ating/deactiv ating ESP
ating ESP®
®
(Electr
(Electr onicSt
onic Stability
ability
Pr
Pr ogr
ogr am)
am) Multimedia system:
4 © 5
Settings 5
Quick access
% ESP®
can only be activated/deactivated using
qu ick access when at least one other function
is available in quick access. ESP ®
can other-
wise be found in theAssistance menu.
* N
NO OTE
TE Mercedes-AMG vehicles #
Obser vethe no tes in the Supplement.
Yo u could otherwise failto recognise
dangers. #
Select ESP. #
Select Onorå Off.
% If ESP ®
is deactivated and drive prog ram
Î was pr eviously selected, drive prog ram
A is automatically activated the next time
th e engine is star ted.
ESP ®
is deactivated if theå ESP®
OFF warn-
ing lamp lights up continuously in the inst rument
cluster.
Obser vethe information on warning lamps and
display message s which may be shown in the
inst rument cluster. F F
unction of EBD
unction of EBD Electronic Breakforce Distribution (EBD) is
char-
acterised bythefo llowing:
R Monitoring and regulating the brake pressure
on there ar wheels.
R Impr oved driving stability when braking, espe-
cially on bends. F
F
unction of S
unction of S TEER C
TEER CONTR
ONTROL
OL ST
EER CONTROL assists youby transmitting a
noticeable steering forc eto the steering wheel in
th e direction requ ired forve hicle stabilisation.
This steering recommendation is given in thefo l-
lowing situations:
R both right wheels or bo thleT wheels are on a
we t or slippery road sur face when you brake
R theve hicle starts toskid
Syst
Syst em limits
em limits
ST EER CONTROL may be impaired or may not
function in thefo llowing situations:
R ESP ®
is deactivated.
R ESP ®
is malfunctioning.
R The steering is malfunctioning.
If ESP ®
is malfunctioning, you will be assisted fur-
th er by the electric po wer steering. 224
224
Driving and parking

R
V
Vehicles wit
ehicles wit h aut
h automatic tr
omatic tr ansmission:
ansmission: the
transmission is shiTed toposition j.
R The vehicle is secured with the electric par k-
ing brake.
In thefo llowing situations, theve hicle is held by
transmission position jand/or bythe electric
parking brake:
R The seat belt is unfastened and the driver's
door is opened.
R The vehicle is switched o..
R There is a system malfunction.
R The po wer supply is insu1cient.
V
V ehicles wit ehicles wit h manual tr
h manual tr ansmission
ansmission
The Brake immediately message may also appear
in the Instrument Displa y:#
Immediately depress the brake pedal /rmly
until thewa rning message disappears.
The HOLD function is deactivated.
A horn sounds at regular inter vals if, despite the
Brake immediately message,you switch o. the
ve hicle, remo veyour seat belt and open the driv-
er's door. If you attem pttolock theve hicle, the horn
tone becomes louder. The vehicle cann otbe
loc ked until you ha vedeactivated the HOLD func-
tion.
% Once you ha veswitched o. theve hicle, you
cannot restart it until you ha vedeactivated
th e HOLD function. F
F
unction of Hill St
unction of Hill Star
art Assist
t Assist Hill
Start Assist holds theve hicle for a short time
when pulling away on a hill under thefo llowing
conditions:
R V
Vehicles wit
ehicles wit h aut
h automatic tr
omatic tr ansmission:
ansmission: the
transmission is in position hork.
R The electric parking brake is released.
This gives you enough time tomo veyour foot
from the brake pedal tothe accelerator pedal and
depress it before theve hicle begins torollaw ay. &
W
WARNI NG
ARNI NGRisk of accident and injury due
to theve hicle rolling away
ATer a sho rttime, Hill Start Assist no lon ger
holds theve hicle. #
SwiTly mo veyour foot from the brake
pedal tothe accelerator pedal. Do not
lea vetheve hicle when it is being held by
Hill Start Assist. F
F
unction of A
unction of A dap
daptiv
tive Br
e Br ak
ake Lights
e Lights Ad
aptive Brake Lights warnfollowing tra1c in an
emer gency braking situation with thefo llowing
actions:
R By 0ashing the brake lamps
R By activating the hazard warning lights
If th eve hicle is braked sharply from speeds abo ve
50 km/h, the brake lamps 0ash rapidl y.This pro-
vides tra1c tr avelling behind you with an even
more noticeable warning.
If th eve hicle is tr avelling at speeds of more than
70 km/h at the beginning of the brake applica-
tion, the hazard warning lights switch on once the
ve hicle is stationar y.When you pull away again,
th e hazard warning lights will switch o. automati-
cally at appr oximately 10 km/h. You can also 226
226
Driving and parking

switch o.
the hazard warning lights using the haz-
ard warning button. S
S
t
tar
ar t-o.
t-o. assist
assist F
F
unction of t
unction of t he
hest
star
ar t-o.
t-o. assist
assist
The start-o. assist enables optimal vehicle accel-
eration from a standstill. Forth is, a suitably high-
gr ip road sur face is requ ired, the tyres and vehicle
must also be in good condition.
Do not activate the start-o. assist on public
ro ads.
Be sure toobser vethe saf ety no tes and informa-
tion on ESP ®
(/ page 222).
A
A ctiv ctiv ating t
ating t he
hest
starar t-o.
t-o. assist
assist &
W WARNING ARNING Risk of skidding and having an
accident from wheels spinning
When you use start-o. assist, individual
wheels could spin and you could lose control
of theve hicle.
If ESP ®
is deactivated, there is a risk of skid-
ding and accident! #
Make sure that no persons or obs tacles
are in the close vicinity of your vehicle. #
Deactivating ESP ®
(/ page 224). #
Movethe steering wheel tothe straight-ahead
position. #
Depress the brake pedal /rmly with your leT
fo ot and keep it depressed. #
Engage theh drive position (/ page 185). #
Select the sportiest available drive prog ram
B orC(/ page 179). #
Rapidly depress the accelerator pedal full y. #
Take your foot o. the brake, but keep the
accelerator pedal depressed.
The vehicle pulls away at maximum accelera-
tion. #
Switch on ESP ®
once the acceleration proce-
dure is comple te. ESP ®
will otherwise not be
able tostabilise theve hicle if theve hicle
starts toskid or a wheel starts tospin.
Cancelling t Cancelling t he
hest
star
ar t-o.
t-o. assist
assist #
Remo veyour foot from the accelerator pedal. #
Reactivate the ESP ®
. A
A
TTENTION ASSIST
TTENTION ASSIST F
F
unction of A
unction of A TTENTION ASSIST
TTENTION ASSIST
AT TENTION ASSIST assists you on long, mono to-
nous journe ys, e.g. on mo torw ays and trunk
ro ads. If ATTENTION ASSIST de tects indicators of
fa tigue or increasing lapses in concentration on
th e part of the driver, it suggests taking a break.
AT TENTION ASSIST is only an aid. It cannot
alw ays de tect fatigue or lapses in concentration in
time. The system is not a substitute for a well-res-
te d and attentive driver. On long journe ys,ta ke
re gular breaks in good time that allow for ade-
qu ate recuperation.
Yo u can choose between two settings:
R St
Standar
andar d:
d:normal system sensitivity.
R Sensitiv
Sensitiv e:
e:higher system sensitivity. The driver
is wa rned earlier and the attention le vel de tec-
te dby ATTENTION ASSIST is ada pted accord-
ingl y.
If dr owsiness or increasing lapses in concent ra-
tion are de tected, theATTENTION ASSIST: Take Driving and parking
227
227

Yo
u can limit the speed as follo ws:
R V
Var
ar iable:
iable: for a short-term speed restriction,
e.g. in built-up areas
R P
P er
er manent
manent :
:fo r a longer-term speed restric-
tion, e.g. in winter ty remode
Yo u can store any speed abo ve20 km/h up tothe
maximum design speed or up tothe set winter
tyre limit. You can also per form settings while the
ve hicle is stationary if theve hicle has been star-
te d.
Obser vethe no tes on driving systems and your
re sponsibility; you may otherwise failto recognise
dangers (/ page 219).
Mer
Mer cedes‑
cedes‑ AMG v
AMG vehicles:
ehicles: the limiter is available
up toa maximum speed of 250 km/h.
Displ ay
Display s in t
s in the Ins
he Instr trument Display
ument Display
R È (gre y): variable limi ter is selected but not
yet activated.
R È (0ashes grey ):va riable limi ter is temp o-
rari lypassive.
R È (gre en): variable limi ter is activated. A stored speed appears along with
theÈ dis-
pla y.The segments in the speedome ter light up,
up tothe cur rently stored speed.
If yo u depress the accelerator pedal be yond the
pressure point (kickdown), theva riable limi ter
switches topassive mode. The Limiter passive
message appears in the Instrument Display and
th eÈ display 0ashes.
The variable limi ter is reactivated in thefo llowing
situations:
R Ifth eve hicle speed drops below the stored
speed.
R Ifth e stored speed is called up.
R Ifyo u store a new speed.
Oper
Oper ating cr
ating cr uise contr
uise contr ol or t
ol or the v
he var
ariable limit
iable limit er
er &
W
WARNING
ARNING Risk of accident due tostored
speed
If yo u call up the stored speed and this is
lo we rth an your cur rent speed, theve hicle
decelerates. #
Take into account the tra1c situation
before calling up the stored speed. R
R
eq
eq uir
uir ements:
ements:
Cruise control R Cruise control is selected.
R ESP ®
must be activated, but not inter vening.
R The vehicle speed is at least 20 km/h.
R The transmission is in position h.
Va riable limi ter
R The variable limi ter is selected. 230
230
Driving and parking

de
tected bythe system. The maximum permissi-
ble speed applying toave hicle with a trailer is not
de tected bythe system.
Ad just the speed in these situations. &
W
WARNING
ARNING Risk of accident due toActive
Speed Limit Assist ada pting theve hicle's
speed
The speed adop tedby Active Speed Limit
Assist may be too high or incor rect in some
individual cases, such as:
R at speed limits below 20 km/h
R inwe t conditions or in fog
R when towing a trailer #
Ensure that the driven speed complies
with tra1c regulations. #
Adjust the driving speed tosuit cur rent
tra1c and weather conditions. F F
unction of r
unction of r out
oute-based speed adapt
e-based speed adapt ation
ation
When Active Distance Assist DISTRONIC is acti va-
te d, theve hicle speed will be adap ted accordingly
to thero ute events ahead. Depending on the drive prog
ram selected, theve hicle neg otiates a route
ev ent ahead in an economical, comfor table or
dynamic manner. When thero ute event has been
passed, theve hicle accelerates again tothe
stored speed. The set distance totheve hicle in
front, vehicles de tected ahead and speed restric-
tions ahead are take n into account.
Yo u can activate and deactivate route-based
speed adap tation in the multimedia system
(/ page 238).
The following route events are take n into account:
R Bends
R T-junctions, roundabouts and toll stations
R Turns and exits
R Tra1c jams ahead (only with Live Tra1c Infor-
mation )
% When theto ll station is reached, Active Dis-
ta nce Assist DISTRONIC ado ptsth e speed as
th e stored speed.
Also, the speed is reduced if the turn signal indi-
cator tochange lanes is switched on and one of
th efo llowing situations is de tected:
R Turning o. at junctions R
Driving on slowing-down lanes
R Driving on lanes adjacent toslowing-down
lanes
The driver is responsible forch oosing theright
speed and observing other road users. This
applies in particular tojunctions, roundabouts and
tra1c lights, as route-based speed adap tation
does not brake theve hicle toa standstill.
When route guidance is active, the /rst speed
adjustment is car ried out automaticall y.Ifth e turn
signal indicator is switched on, the selected route
is con/rmed and fur ther speed adjustment is acti-
va ted.
Speed adap tation is cancelled in thefo llowing
cases:
R Ifth e turn signal indicator is switched o.
before thero ute event.
R Ifth e driver depresses the accelerator or
brake pedal during the process.
Syst
Syst em limits em limits
Ro ute-based speed adap tation does not take right
of wa yre gulations into account. The driver is Driving and parking
237
237

S
S
t
tatus displa
atus displa y of A
y of Activ
ctiveSt
e St eer
eer ing Assis
ing Assist in t t in the
he
Ins
Instr trument Display
ument Display
R Ø (gre y): acti vated and passive
R Ø (gre en): activated and active
R Ø (red): system limits de tected
R Ø (white, red hands): "hands on the steer-
ing wheel" prom pt
% During the transition from active topassive
status, theØ symbol is shown as enlar ged
and 0ashing. Once the system is passive, the
Ø symbol is shown as grey inthe Instru-
ment Displa y.
% Depending on the selected vehicle settings,
Ac tive Steering Assist may be una vailable.
St
St eer
eer ing and t
ing and t ouc
ouch det
h det ection
ection
The driver is requ ired tokeep their hands on the
stee ring wheel at all times and be able tointer-
ve ne at any time tocor rect the course of theve hi-
cle and keep it in lane. The driver must expect a
ch ange from active topassive mode or vice versa
at any time. If
th e system de tects that the driver has not
steered theve hicle for a considerable period of
time or has remo vedth eir hands from the steering
wheel, display 1appears. If the driver still does
not steer theve hicle, a warning tone sounds in
addition tothe visual warning message.
If th e driver does not react tothewa rning for a
considerable period, the system can initiate an
emer gency stop (/ page 240).
The warning is not issued or is stopped when the
driver gives con/ rmation tothe system:
R The driver steers theve hicle. R
Depending on t
Depending on t he country
he country:
:th e driver presses
a steering wheel button or operates Touch
Control
If Ac tive Steering Assist de tects that a system
limit has been reached, a visual warning is issued
and a warning tone sounds.
Obser vethe no tes on driving systems and your
re sponsibility; you may otherwise failto recognise
dangers (/ page 219).
Syst
Syst em limits
em limits
Ac tive Steering Assist has a limited steering tor-
qu efo r lateral guidance. In some cases, the steer-
ing inter vention is not su1cient tokeep theve hi-
cle in the lane or todrive thro ugh exits.
The system may be impaired or may not function
in thefo llowing instances:
R There is poor visibility, e.g. due tosno w,rain,
fo g, heavy spr ay,gr eatly varying light condi-
tions or strong shadow s onthe car riag ewa y.
R There is glare, e.g. from oncoming tra1c,
di re ct sunlight or re0ections.
R Insu1cient road illumination. Driving and parking
239 239

to
ne sounds in addition tothe visual warning mes-
sage.
If th e driver still does not respond tothewa rning,
th eBeginning emergency stop message appears
in the Instrument Displa y.Ifth e driver still does
not respond, Active Distance Assist DISTRONIC
re duces the speed. The vehicle is decelerated in
stages toa standstill.
Depending on the countr y,at speeds below
60 km/h the hazard warning lights switch on
automaticall y.
When theve hicle is stationar y,thefo llowing
actions are car ried out:
R The vehicle is secured with the electric par k-
ing brake.
R Active Distance Assist DISTRONIC is ended.
R The vehicle is unloc ked.
R If possible, an emer gency call is placed tothe
Mercedes-Benz eme rgency call centre.
The driver can cancel the deceleration at any time
by per form ing one of thefo llowing actions:
R Steering R
Braking or accelerating
R Deactivating Active Distance Assist
DISTRONIC A A
ctiv
ctiv e Br
e Br ak
ake Assist
e Assist F
F
unction of A
unction of A ctiv
ctive Br
e Br ak
ake Assist
e Assist
Ac tive Brake Assist consists of thefo llowing func-
tions:
R Distance warning function
R Autonomous braking function
R Situation-dependent braking assistance
R V
Vehicles wit
ehicles wit h Dr
h Driving Assist
iving Assist ance P
ance Pack
ackag
age:
e: Eva-
sive Steering Assist and cornering function
Ac tive Brake Assist can help youto minimise the
ri sk of a collision with vehicles, cyclists or pedes-
trians or toreduce the e.ects of such a collision.
If Ac tive Brake Assist has de tected a risk of colli-
sion, a warning tone sounds and theL dis-
ta nce warning lamp lights up in the inst rument
cluster. V V
ehicles wit ehicles wit h PRE-S
h PRE-SAFE
AFE®
®
:
:depending on the coun-
tr y, an additional haptic warning occurs in the
fo rm of slight, repeated tensioning of the seat
belt.
If yo u do not react tothewa rning, autonomous
braking can be initiated in critical situations.
In especially critical situations, Active Brake Assist
can initiate autonomous braking directl y.In this
case, thewa rning lamp and warning tone occur
simultaneously with the braking application.
If yo u apply the brake yourself in a critical situa-
tion or apply the brake during autonomous brak-
ing, situation-dependent braking assistance
occurs. The brake pressure increases up tomaxi-
mum full-s top braking if necessar y.
Obser vethe no tes on driving systems and your
re sponsibility; you may otherwise failto recognise
dangers (/ page 219). Driving and parking
241 241

If autonomous braking or situation-dependent
braking assis
tance has occur red, display 1
appears in the Instrument Display and then auto-
matically goes out aTer a short time.
If th e autonomous braking function or the situa-
tion-dependent braking assistance is triggered,
additional pr eventive measures for occupant pro-
te ction (PRE- SAFE®
) may also be initiated. &
W WARNING ARNING Risk of an accident caused by
limited de tection per form ance of Active
Brake Assist
Ac tive Brake Assist cannot alw ays clear lyiden-
tify objects and complex tra1c situations. In such cases,
Active Brake Assist might:
R Give a warning or brake without reason
R Not give a warning or not brake
Ac tive Brake Assist is only an aid. The driver is
re sponsible for maintaining a su1ciently safe
distance totheve hicle in front, vehicle speed
and for braking in good time. #
Always pay careful attention tothe tra1c
situation; do not relyonActive Brake
Assist alone. #
Be prepa redto brake or swer veif neces-
sar y. Also obser
vethe system limits of Active Brake
Assist.
The individual subfunctions ar The individual subfunctions ar eav
e av ailable in v
ailable in v ar
ari-
i-
ous speed r
ous speed r ang
anges:
es:
The dis tance warning function can issue a warn-
ing in thefo llowing situations:
R From appr oximately 30 km/h, if over se veral
seconds the distance maintained totheve hi-
cle tr avelling in front is insu1cient forthe driven speed,
theL distance warning lamp
lights up in the inst rument clus ter.
R From appr oximately 7 km/h, if your vehicle is
critically close toave hicle, cyclist or pedes-
trian, you will hear an intermittent warning
to ne and theL distance warning lamp
lights up in the inst rument clus ter.
V
V ehicles wit
ehicles wit h PRE-S
h PRE-SAFE
AFE®
®
:
:depending on the
count ry, an additional haptic warning occurs
in thefo rm of slight, repeated tensioning of
th e seat belt.
Brake immediately or take evasive action, pr ovi-
ded it is safe todo so and the tra1c situation
allo ws th is.
Dist
Dist ance w
ance w ar
arning function (v
ning function (v ehicles wit
ehicles wit hout Dr
hout Driv-
iv-
ing Assist
ing Assist ance P
ance Pack
ackag
age)
e)
The distance warning function can aid you in the
fo llowing situations with an intermittent warning
to ne and a warning lamp:
R at speeds up toappr oximately 250 km/h
when approaching vehicles ahead 242
242
Driving and parking