check HYUNDAI SONATA 2021 Repair Manual

6-24
Parking brake warning light
Check the parking brake
warning light by placing the
ignition switch to the ON
position (do not start the
engine).
This light will be illuminated when the
parking brake is applied with the ignition
switch in the START or ON position.
If the parking brake warning light
remains on after the parking brake
is released while engine is running,
there may be a malfunction in the
brake system. Immediate attention is
necessary.
If at all possible, cease driving the vehicle
immediately. If that is not possible,
use extreme caution while operating
the vehicle and only continue to drive
the vehicle until you can reach a safe
location.
Emergency braking
If there is a problem with the brake
pedal while driving, emergency braking
is possible by pulling up and holding
the EPB switch. Braking is possible only
while you are holding the EPB switch.
However, braking distance will be longer
than normal.
WARNING
Do not operate the parking brake while
the vehicle is moving except in an
emergency situation. It could damage
the brake system and lead to a severe
accident.
Information
During emergency braking, the parking
brake warning light will illuminate to
indicate that the system is operating.
NOTICE
If you continuously notice a noise or
burning smell when the EPB is used
for emergency braking, have system
checked by an authorized HYUNDAI
dealer.
When the EPB (Electronic Parking Brake)
does not release
If the EPB does not release normally,
contact an authorized HYUNDAI dealer
by loading the vehicle on a flatbed tow
truck and have the system checked.
Auto Hold
The Auto Hold maintains the vehicle in a
standstill even though the brake pedal is
not depressed after the driver brings the
vehicle to a complete stop by depressing
the brake pedal.
To apply :
ODN8069015
1. With the driv er's door and engine
hood closed, depress the brake
pedal and then press the [AUTO
HOLD] switch. The white AUTO HOLD
indicator will come on and the system
will be in the standby position.
••CLUSTER
While Driving

6-26
In these cases, the parking brake
warning light comes on, the AUTO
HOLD indicator changes from green
to white, and a warning sound and a
message will appear to inform you that
EPB has been automatically engaged.
Before driving off again, press foot
brake pedal, check the surrounding
area near your vehicle and release
parking brake manually with the EPB
switch.
• While operating Auto Hold, you may
hear mechanical noise. However, it is
normal operating noise.
NOTICE
If the AUTO HOLD indicator changes
to yellow, the Auto Hold is not working
properly. Contact an authorized
HYUNDAI dealer.
WARNING
• Depress the accelerator pedal slowly
when you start the vehicle.
• For your safety, cancel the Auto Hold
when you drive downhill, back up the
vehicle or park the vehicle.
NOTICE
If there is a malfunction with the
driver's door or engine hood open
detection system, the Auto Hold may
not work properly.
Contact an authorized HYUNDAI dealer.
Warning messages
OTM058187L
Parking brake automatically engaged
When the EPB is applied from Auto Hold,
a warning will sound and a message will
appear.
OIK057079N
AUTO HOLD turning Off!
Press brake pedal
When the conversion from Auto Hold to
EPB is not working properly a warning
will sound and a message will appear.
When this message is displayed, the Auto
Hold and EPB may not operate. For your
safety, depress the brake pedal.
While Driving

06
6-29
Electronic Stability Control (ESC)
ODN8069018
The Electronic Stability Control (ESC)
system helps to stabilize the vehicle
during cornering maneuvers. ESC checks
where you are steering and where the
vehicle is actually going. ESC applies
braking pressure to any one of the
vehicle's brakes and intervenes in the
engine management system to assist the
driver with keeping the vehicle on the
intended path. It is not a substitute for
safe driving practices. Always adjust your
speed and driving to the road conditions.
WARNING
Never drive too fast for the road
conditions or too quickly when
cornering. The ESC system will not
prevent accidents.
Excessive speed in turns, abrupt
maneuvers, and hydroplaning on wet
surfaces can result in severe accidents.
ESC operation
ESC ON condition
When the ignition switch is in the
ON position, the ESC and the ESC
OFF indicator lights illuminate for
approximately three seconds. After both
lights go off, the ESC is enabled.
When operating
When the ESC is in operation,
the ESC indicator light blinks:
• When you apply your brakes under
conditions which may lock the wheels,
you may hear sounds from the brakes,
or feel a corresponding sensation in
the brake pedal. This is normal and it
means your ESC is active.
• When the ESC activates, the engine
may not respond to the accelerator as
it does under routine conditions.
• If the Cruise Control was in use when
the ESC activates, the Cruise Control
automatically disengages. The Cruise
Control can be reengaged when the
road conditions allow. See "Cruise
Control System" later in this chapter.
(if equipped)
• When moving out of the mud or
driving on a slippery road, the engine
RPM (revolutions per minute) may
not increase even if you press the
accelerator pedal deeply. This is to
maintain the stability and traction of
the vehicle and does not indicate a
problem.

6-30
ESC OFF condition
To cancel ESC operation:
• State 1
Press the ESC OFF button briefly. The
ESC OFF indicator light and message
"Traction Control disabled" will
illuminate. In this state, the traction
control function of ESC (engine
management) is disabled, but the
brake control function of ESC (braking
management) still operates.
• State 2
Press and hold the ESC OFF button
continuously for more than 3 seconds.
The ESC OFF indicator light and message
"Traction and Stability Control disabled"
illuminates and a warning chime sounds.
In this state, both the traction control
function of ESC (engine management)
and the brake control function of ESC
(braking management) are disabled.
If the ignition switch is placed to the
LOCK/OFF position when ESC is off, ESC
remains off. Upon restarting the engine,
the ESC will automatically turn on again.Indicator lights
■ ESC indicator light (blinks)
■ ESC OFF indicator light (comes on)
When the ignition switch is placed to
the ON position, the ESC indicator light
illuminates, then goes off if the ESC
system is operating normally.
The ESC indicator light blinks whenever
the ESC is operating.
If ESC indicator light stays on, your
vehicle may have a malfunction with
the ESC system. When this warning light
illuminates have your vehicle checked by
an authorized HYUNDAI dealer as soon
as possible.
The ESC OFF indicator light comes on
when the ESC is turned off.
WARNING
When the ESC is blinking, this indicates
the ESC is active:
Drive slowly and NEVER attempt to
accelerate. NEVER turn the ESC off
while the ESC indicator light is blinking
or you may lose control of the vehicle
resulting in an accident.
NOTICE
Driving with wheels and tires with
different sizes may cause the ESC
system to malfunction. Before replacing
tires, make sure all four tires and wheels
are the same size. Never drive the
vehicle with different sized wheels and
tires installed.
While Driving

06
6-31
ESC OFF usage
When Driving
The ESC OFF mode should only be used
briefly to help free the vehicle if stuck in
snow by temporarily stopping operation
of the ESC to maintain wheel torque.
To turn ESC off while driving, press the
ESC OFF button while driving on a flat
road surface.
NOTICE
To prevent damage to the transmission:
• Do not allow wheel(s) of one axle to
spin excessively while the ESC, ABS,
and parking brake warning lights
are displayed. The repairs would not
be covered by the vehicle warranty.
Reduce engine power and do not
spin the wheel(s) excessively while
these lights are displayed.
• When operating the vehicle on
a dynamometer, make sure the
ESC is turned off (ESC OFF light
illuminated).
Information
Turning the ESC off does not affect ABS
or standard brake system operation.
Vehicle Stability Management
(VSM)
The Vehicle Stability Management (VSM)
is a function of the Electronic Stability
Control (ESC) system. It helps ensure the
vehicle stays stable when accelerating
or braking suddenly on wet, slippery and
rough roads where traction over the four
tires can suddenly become uneven.
WARNING
Take the following precautions when
using the Vehicle Stability Management
(VSM):
• ALWAYS check the speed and the
distance to the vehicle ahead. The
VSM is not a substitute for safe
driving practices.
• Never drive too fast for the road
conditions. The VSM system will not
prevent accidents. Excessive speed
in bad weather, slippery and uneven
roads can result in severe accidents.
VSM operation
VSM ON condition
The VSM operates when:
The Electronic Stability Control (ESC) is
on.
When operating
When you apply your brakes under
conditions which may activate the ESC,
you may hear sounds from the brakes,
or feel a corresponding sensation in the
brake pedal. This is normal and it means
your VSM is active.
NOTICE
The VSM does not operate when:
• Driving on a banked road such as
gradient or incline.
• Driving rearward.
• ESC OFF indicator light is on.
• EPS (Electric Power Steering)
warning light (
) is on or blinks.

6-32
WARNING
If ESC indicator light () or EPS
warning light () stays on or blinks,
your vehicle may have a malfunction
with the VSM system. When the
warning light illuminates, have your
vehicle checked by an authorized
HYUNDAI dealer as soon as possible.
Driving with wheels and tires with
different sizes may cause the ESC system
to malfunction. Before replacing tires,
make sure all four tires and wheels are
the same size. Never drive the vehicle
with different sized tires and wheels
installed.
Hill-Start Assist Control (HAC)
The Hill-Start Assist Control (HAC)
helps prevent the vehicle from rolling
backwards when starting a vehicle from
a stop on a hill. The system operates the
brakes automatically for approximately
2 seconds and releases the brake after 2
seconds or when the accelerator pedal is
depressed.
WARNING
Always be ready to depress the
accelerator pedal when starting off on
a incline. The HAC activates only for
approximately 2 seconds.
NOTICE
• The HAC does not operate when
the shift button is in P (Park) or N
(Neutral)
• The HAC activates even though the
ESC (Electronic Stability Control) is
off but does not activate when the
ESC has malfunctioned.
Good Braking Practices
WARNING
Whenever leaving the vehicle or
parking, always come to a complete
stop and continue to depress the brake
pedal. Move the shift button into P
(Park) position, then apply the parking
brake, and place the ignition switch in
the LOCK/OFF position.
Vehicles parked with the parking brake
not applied or not fully engaged may
roll inadvertently and may cause injury
to the driver and others. ALWAYS apply
the parking brake before exiting the
vehicle.
Wet brakes can be dangerous! The
brakes may get wet if the vehicle is
driven through standing water or if it
is washed. Your vehicle will not stop as
quickly if the brakes are wet. Wet brakes
may cause the vehicle to pull to one side.
To dry the brakes, apply the brakes
lightly until the braking action returns to
normal, taking care to keep the vehicle
under control at all times. If the braking
action does not return to normal, stop
as soon as it is safe to do so and call
an authorized HYUNDAI dealer for
assistance.
DO NOT drive with your foot resting on
the brake pedal. Even light, but constant
pedal pressure can result in the brakes
overheating, brake wear, and possibly
even brake failure.
If a tire goes flat while you are driving,
apply the brakes gently and keep the
vehicle pointed straight ahead while you
slow down. When you are moving slowly
enough for it to be safe to do so, pull off
the road and stop in a safe location.
Keep your foot firmly on the brake pedal
when the vehicle is stopped to prevent
the vehicle from rolling forward.
While Driving

06
6-33
The Idle Stop and Go (ISG) system
automatically and temporarily shuts
down the engine when the vehicle
is stopped and idling to improve fuel
efficiency and reduce exhaust gas
emissions. (i.e. red stop light, stop sign,
and traffic jam).
The engine is automatically started upon
satisfying the starting conditions.
The ISG system is always active, when
the engine is running.
Information
When the engine is automatically started
by the ISG system, some warning
lights (i.e. ABS, ESC, ESC OFF, EPS,
and parking brake warning light) may
illuminate for a few seconds due to the
low battery voltage. However, it does
not indicate a malfunction with the ISG
system.
To Activate the ISG System
Prerequisite for activation
The ISG system operates in the following
situations.
• The driver's seatbelt is fastened
• The driver's door and hood are closed
• The brake vacuum pressure is
adequate
• The battery sensor is activated and
the battery is sufficiently charged
• Outside temperature is not too low or
too high
• The vehicle is driven over a constant
speed and stops
• The climate control system satisfies
the conditions
• The vehicle is sufficiently warmed up
• The incline is gradual
• The steering wheel is turned less than
180 degrees and then the vehicle
stops
Information
• The ISG system is not
activated, when the
prerequisites to activate
the ISG system are
unsatisfied. In this case,
the ISG OFF button indicator
illuminates, and the auto stop indicator
(
) illuminates in yellow on the
instrument cluster.
• When the above indicator remains
illuminated on the instrument cluster,
have the IGS system checked by an
authorized HYUNDAI dealer.
Auto stop
To stop the engine in idle stop mode
1.

Decr
ease the vehicle speed to 0 mph.
2.

Depr
ess the brake pedal with the shift
button in D (Drive) or N (Neutral).
The auto stop indicator (
) illuminates
in green on the instrument cluster, when
the engine stops.
Information
The driving speed must reach at least 3
mph (5 km/h) after an idle stop to stop the
engine in idle stop mode again.
In auto stop mode, when the driver
opens the hood, the ISG system will be
deactivated.
ISG (Idle Stop and Go) SyStem ( I f equ I pped)

06
6-35
OIK057086N
The auto start is temporarily deactivated
in the following situations.
When the gear is shifted from N (Neutral)
to R (Reverse), D (Drive) or Manual
shift mode without the brake pedal
depressed. A message "Press brake pedal
for Auto Start" will appear on the LCD
display. To activate auto start, depress
the brake pedal.
To Deactivate the ISG System
• Press the ISG OFF button to
deactivate the ISG system. Then, the
ISG OFF button indicator illuminates.
• Press the ISG OFF button again to
reactivate the ISG system. Then, the
ISG OFF button indicator turns OFF.
ISG System Malfunction
The ISG system may not operate:
When there is a malfunction with the ISG
sensors or the ISG system.
The followings occur, when there is a
malfunction with the ISG system:
• The auto stop indicator (
) will blink
in yellow on the instrument cluster.
• The light on the ISG OFF button will
illuminate.
Information
• When you cannot turn OFF the ISG
OFF button indicator by pressing
the ISG OFF button, or when the
malfunction with the ISG system
persists, contact an authorized
HYUNDAI dealer.
• You can turn off the ISG OFF button
indicator by driving over 50 mph (80
km/h) for up to 2 hours with the fan
speed below the 2nd position. If the
ISG OFF button indicator remains
ON, contact an authorized HYUNDAI
dealer.
WARNING
When the engine is in auto stop mode,
the engine may restart. Before leaving
the vehicle or checking the engine
compartment, stop the engine placing
the ignition switch to the LOCK/OFF
position or remove the ignition key.

6-36
Battery Sensor Deactivation
ODN8A069204
[A] : Battery sensor
The battery sensor is deactivated, when
the battery is disconnected from the
negative pole for maintenance purpose.
In this case, the ISG system is limitedly
operated due to the battery sensor
deactivation. Thus, the driver needs
to take the following procedures to
reactivate the battery sensor after
disconnecting the battery.
Prerequisites to reactivate the
battery sensor
Switch "ON" and "OFF" the ignition one
time. Park the vehicle for a minimum of 4
hours with the hood and all doors closed.
Pay extreme caution not to connect any
accessories (i.e. navigation and black
box) to the vehicle with the engine in the
OFF status. If not, the battery sensor may
not be reactivated.
Information
The ISG system may not operate in the
following situations.
-Ther

e is a malfunction with the ISG
system.
- The battery is weak.
-The brake vacuum pr

essure is low.
If this occurs, have the ISG system
checked by an authorized HYUNDAI
dealer.
NOTICE
• Use only a genuine HYUNDAI
Absorbent Glass Mat (AGM) battery
for replacement. If not, the ISG
system may not operate normally.
• Do not recharge the Absorbent Glass
Mat (AGM) battery with a general
battery charger. It may damage or
explode the Absorbent Glass Mat
(AGM) battery.
• Do not remove the battery cap. The
battery electrolyte, which is harmful
to the human body, may leak out.
While Driving

6-44
Brake operation
• In an urgent situation, the braking
system enters into the ready status for
prompt reaction against the driver’s
depressing the brake pedal.
• FCA provides additional braking
power for optimum braking
performance, when the driver
depresses the brake pedal.
• The braking control is automatically
deactivated, when the driver sharply
depresses the accelerator pedal, or
when the driver abruptly operates the
steering wheel.
• FCA brake control is automatically
canceled, when risk factors disappear.
CAUTION
• The driver should always use
extreme caution while operating
the vehicle, whether or not there is a
warning message or alarm from FCA
system.
• After the brake control is activated,
the driver must immediately depress
the brake pedal and check the
surroundings. The brake activation
by the system lasts for about 2
seconds.
• If any other warning sound such as
seat belt warning chime is already
generated, Forward Collision-
Avoidance Assist system warning
may not sound.
• Playing the vehicle audio system at
high volume may prevent occupants
from hearing the system warning
sounds.
WARNING
The braking control cannot completely
stop the vehicle nor avoid all
collisions. The driver should hold the
responsibility to safely drive and control
the vehicle.
WARNING
The FCA system logic operates within
certain parameters, such as the
distance from the vehicle, pedestrian or
cyclist (if equipped) ahead, the speed
of the vehicle ahead, and the driver’s
vehicle speed. Certain conditions
such as inclement weather and road
conditions may affect the operation of
FCA system.
WARNING
Never deliberately drive dangerously to
activate the system.
Information
Exceptional operation of the braking assist
system
• The vehicle drives on a slope or curve.
• The vehicle drives by a pedestrian or
cyclist at the crossroads, traffic signals
or structure.
• The vehicle drives through a tunnel or
near a railroad.
• The vehicle drives where steam, smoke
or shadow is on the road.
• The vehicle drives the road tree planted
or streetlamps installed.
• There is interference by
electromagnetic waves or electric noise.
While Driving