brake LEXUS UX250H 2019 Workshop Manual

2514-5. Using the driving support systems
4
Driving
• If a sensor is covered with ice, snow, dirt, etc. (when cleared, the system will return
to normal)
• If heavy rain or water strikes a sensor
• When driving in incl ement weather such
as fog, snow or a sandstorm
●Other ultrasonic wave sources
• When vehicle horns, vehicle detectors,
motorcycle engines, air brakes of large
vehicles, the clearance sonar of other
vehicles or other devices which produce
ultrasonic waves are near the vehicle
• If a sticker or an el ectronic component,
such as a backlit license plate (especially
fluorescent type), fog lights, fender pole
or wireless antenna is installed near a
sensor
●Changes in the vehicle posture
• If the vehicle is significantly tilted
• If the front of the vehicle is raised or low-
ered due to the carried load
• If the orientation of a sensor has been
changed due to a collision or other
impact
■Situations in which the Parking Support
Brake function (stati c objects) may not
operate properly
In some situations, such as the following, this
function may not operate properly.
●Weather
• When a sensor or the area around a sen- sor is extremely hot or cold
• When strong winds are blowing • If a sensor is covered with ice, snow, dirt,
etc. (when cleared, the system will return
to normal)
• If heavy rain or water strikes a sensor
• When driving in incl ement weather such
as fog, snow or a sandstorm
●Vehicle surroundings
• When an object that cannot be detected
is between the vehicle and a detected
object
• If an object such as a vehicle, motorcycle,
bicycle or pedestrian cuts in front of the
vehicle or runs out from the side of the
vehicle
●Other ultrasonic waves sources
• When vehicle horns, vehicle detectors,
motorcycle engines, air brakes of large
vehicles, the clearance sonar of other
vehicles or other de vices which produce
ultrasonic waves are near the vehicle
• If a sticker or an electronic component, such as a backlit license plate (especially
fluorescent type), fog lights, fender pole
or wireless antenna is installed near a
sensor
●Changes in the vehicle posture
• If the vehicle is significantly tilted
• If the front of the vehicle is raised or low-
ered due to the carried load
• If the orientation of a sensor has been
changed due to a collision or other
impact

2524-5. Using the driving support systems
*: If equipped
This function will operate in situations
such as the following if a vehicle is
detected in the traveling direction of
the vehicle.
■When reversing, a vehicle is
approaching and the brake pedal is
not depressed, or is depressed late
 P.228
■The Parking Support Brake function
(rear-crossing vehicles) will operate
when
The function will operate when the PKSB
OFF indicator is not illuminated or flashing
(  P.75, 76) and all of the following condi-
tions are met:
●Hybrid system output restriction control
• The Parking Support Brake is enabled.
• The vehicle speed is 10 mph (15 km/h) or less.
• Vehicles are approaching from the right or left at the rear of the vehicle at a travel-
ing speed of more than approximately 5
mph (8 km/h)
• The shift lever is in R.
• The Parking Support Brake determines
that a stronger than normal brake opera-
tion is necessary to avoid a collision with
Parking Support Brake func-
tion (rear-crossing vehicles)*
If a rear radar sensor detects a vehi-
cle approaching from the right or
left at the rear of the vehicle and the
system determines that the possi-
bility of a collision is high, this func-
tion will perform brake control to
reduce the likelihood of an impact
with the approaching vehicle.
Examples of function operation
Types of sensors
WARNING
■To ensure the Parking Support Brake
(rear-crossing vehicles) can operate
properly
Observe the following precautions
regarding the rear radar sensors
(  P.228). Failure to do so may cause a
sensor to not operate properly, and may
cause an accident.
●Do not modify, disassemble or paint
the sensors.
●Do not replace a rear radar sensor
with a part other than a genuine part.
●Do not damage the rear radar sensors,
and always keep the radar sensors and
their surrounding area on the bumper
clean.
■To prevent a rear radar sensor from
malfunctioning
●If the area around a rear radar sensor
is subjected to an impact, the system
may not operate properly due to a
sensor malfunction. Have the vehicle
inspected by your Lexus dealer.
●Observe the rear radar sensor han-
dling precautions. ( P.228)

2534-5. Using the driving support systems
4
Driving
an approaching vehicle.
●Brake control
• Hybrid system output restriction control is operating.
• The Parking Support Brake determines
that an emergency brake operation is
necessary to avoid a collision with an
approaching vehicle.
■The Parking Support Brake function
(rear-crossing vehicles) will stop operat-
ing when
The function will stop operating if any of the
following conditions are met:
●Hybrid system output restriction control
• The Parking Support Brake is disabled.
• The collision becomes avoidable with normal brake operation.
• A vehicle is no longer approaching from the right or left at the rear of the vehicle.
●Brake control
• The Parking Support Brake is disabled.
• Approximately 2 seconds have elapsed
since the vehicle was stopped by brake
control.
• The brake pedal is depressed after the vehicle is stopped by brake control.
• A vehicle is no longer approaching from
the right or left at the rear of the vehicle.
■Detection area of the Parking Support
Brake function (rear-crossing vehicles)
The detection area of the Parking Support
Brake function (rear-crossing vehicles) dif-
fers from the detection area of the RCTA
function ( P.240). Therefore, even if the
RCTA function detects a vehicle and pro-
vides an alert, the Parking Support Brake
function (rear-crossing vehicles) may not
start operating.
■Conditions under which the Parking
Support Brake function (rear-crossing
vehicles) will not detect a vehicle
The Parking Support Brake function (rear-
crossing vehicles) is not designed to detect
the following types of vehicles and/or
objects:
●Vehicles approaching from directly
behind
●Vehicles backing up in a parking space
next to your vehicle
●Vehicles that the sensors cannot detect
due to obstructions
●Vehicles which suddenly accelerate or
decelerate near your vehicle
●Guardrails, walls, signs, parked vehicles
and similar stationary objects*
●Small motorcycles, bicycles, pedestrians,
etc.*
●Vehicles moving away from your vehicle
●Vehicles approaching from the parking
spaces next to your vehicle*
●Objects which are extremely close to a
radar sensor*
●Vehicles which are approaching from the
right or left at the rear of the vehicle at a
traveling speed of less than approxi-
mately 5 mph (8 km/h)
●Vehicles which are approaching from the
right or left at the rear of the vehicle at a
traveling speed of more than approxi-
mately 15 mph (24 km/h)
*: Depending on the conditions, detection
of a vehicle and/or object may occur.
■RCTA buzzer
Regardless of whether th e RCTA function is
enabled or not ( P.239), if the Parking
Support Brake function is enabled
(  P.244) and brake control is performed,
a buzzer will sound to notify the driver.
■Situations in which the system may
operate even though there is no possi-
bility of a collision
In some situations such as the following, the
Parking Support Brake function (rear-
crossing vehicles) may operate even
though there is no possibility of a collision.
●When the parking space faces a street

2544-5. Using the driving support systems
and vehicles are being driven on the
street
●When a detected vehicle turns while
approaching the vehicle
●When a vehicle passes by the side of your
vehicle
●When the distance between your vehicle
and metal objects, such as a guardrail,
wall, sign, or parked vehicle, which may
reflect electrical waves toward the rear of
the vehicle, is short
●When there are spinning objects near
your vehicle such as the fan of an air con-
ditioning unit
●When water is splashed or sprayed toward the rear bumper, such as from a
sprinkler
■Situations in which the Parking Support
Brake function (rear-crossing vehicles)
may not operate properly
In some situations, such as the following, the
radar sensors may not detect an object and
this function may not operate properly
●Stationary objects
●When a sensor or the area around a sen-
sor is extremely hot or cold
●If the rear bumper is covered with ice,
snow, dirt, etc.
●When it is raining he avily or water strikes
the vehicle
●When the detection area of a radar sen-
sor is obstructed by an adjacent vehicle
●If the vehicle is significantly tilted
●When equipment that may obstruct a
sensor is installed, such as a towing eye-
let, bumper protector (an additional trim
strip, etc.), bicycle carrier, or snow plow
●If the suspension has been modified or
tires of a size othe r than specified are
installed
●If the front of the vehicle is raised or low-
ered due to the carried load
●If a sticker or an el ectronic component,
such as a backlit license plate (especially
fluorescent type), fog lights, fender pole
or wireless antenna is installed near a
radar sensor
●If the orientation of a radar sensor has
been changed
●When multiple vehicl es are approaching
with only a small gap between each vehi-
cle
●If a vehicle is approaching the rear of
your vehicle rapidly
●Situations in which the radar sensor may
not detect a vehicle
• When a vehicle approaches from the right or left at the rear of the vehicle while
you are turning while backing up
• When turning while backing up

2564-5. Using the driving support systems
the “Eco” indicator comes on.
3Sport mode
Assists acceleration response by con-
trolling the hybrid system and steering.
Suitable for when precise handling is desir-
able, for example when driving on moun-
tain roads.
When not in Sport mode, if the driving
mode select switch is turned backward, the
“Sport” indicator comes on and the Hybrid
System Indicator changes to the tachome-
ter. ( P.78, 82)
■Operation of the air conditioning sys-
tem in Eco drive mode
Eco drive mode controls the heating/cool-
ing operations and fan speed of the air con-
ditioning system to enhance fuel efficiency.
To improve air condit ioning performance,
perform the following operations:
●Turn off eco air conditioning mode
(  P.278)
●Adjust the fan speed ( P.276, 279)
●Turn off Eco drive mode
■Automatic deactivation of Sport mode
If the power switch is turned off after driving
in Sport mode, the driving mode will be
changed to Normal mode.
■Driving mode pop-up display (vehicles
with 10.3-inch display model)
When the driving mode is changed, the
selected driving mode will be temporarily
displayed on the side display. ( P.273)
■ECB (Electronically Controlled
Brake System)
The electronically controlled system
generates braking force correspond-
ing to the brake operation
■ABS (Anti-lock Brake System)
Helps to prevent wheel lock when the
brakes are applied suddenly, or if the
brakes are applied while driving on a
slippery road surface
■Brake assist
Generates an increased level of brak-
ing force after the brake pedal is
depressed when the system detects a
panic stop situation
■VSC (Vehicle Stability Control)
Helps the driver to control skidding
when swerving sudden ly or turning on
slippery road surfaces
■Enhanced VSC (Enhanced Vehi-
cle Stability Control)
Provides cooperative control of the
ABS, TRAC, VSC and EPS.
Driving assist systems
To keep driving safety and perfor-
mance, the following systems oper-
ate automatically in response to
various driving situations. Be aware,
however, that these systems are
supplementary and should not be
relied upon too heavily when oper-
ating the vehicle.
Summary of the driving assist
systems

2574-5. Using the driving support systems
4
Driving
Helps to maintain directional stability
when swerving on slippery road sur-
faces by controlling steering perfor-
mance.
■Secondary Collision Brake
When the airbag sensor detects a colli-
sion, the brakes and brake lights are
automatically controlled to reduce the
vehicle speed and that helps reduce
the possibility of further damage due to
a secondary collision
■TRAC (Traction Control)
Helps to maintain drive power and pre-
vent the drive wheels from spinning
when starting the vehicle or accelerat-
ing on slippery roads
■Active Cornering Assist (ACA)
Helps to prevent the vehicle from drift-
ing to the outer side by performing
inner wheel brake control when
attempting to accelerate during cor-
nering
■Hill-start assist control
Helps to reduce the backward move-
ment of the vehicle when starting on an
uphill
■EPS (Electric Power Steering)
Employs an electric motor to reduce
the amount of effort needed to turn the
steering wheel
■E-Four (AWD models)
Electronic On-Demand AWD system.
Automatically switches from front-
wheel drive to all-wheel drive (AWD)
according to the driving conditions,
helping to ensure reliable handling and stability. Examples of
conditions where
the system will switch to AWD are
when cornering, going uphill, starting
off or accelerating, and when the road
surface is slippery due to snow, rain,
etc.
■When the TRAC/VSC/ABS systems are
operating
The slip indicator light will flash while the
TRAC/VSC/ABS systems are operating.
■Disabling the TRAC system
If the vehicle gets stuck in mud, dirt or snow,
the TRAC system may reduce power from
the hybrid system to the wheels. Pressing
the switch to turn the system off may
make it easier for you to rock the vehicle in
order to free it.
To turn the TRAC system off, quickly press
and release the switch.
The “Traction Co ntrol Turned Off” will be
shown on the multi-information display.
Press the switch again to turn the sys-
tem back on.
■Disabling both TRAC and VSC systems
To turn the TRAC and VSC systems off,

2584-5. Using the driving support systems
press and hold the switch for more
than 3 seconds while the vehicle is stopped.
The VSC OFF indicator light will come on
and the “Traction Control Turned Off” will
be shown on the multi-information display.
*
Press the switch again to turn the sys-
tem back on.
*: Pre-collision brake assist and pre-colli- sion braking will also be disabled. The
PCS warning light will come on and the
message will be shown on the multi-infor-
mation display. ( P.204)
■When the message is displayed on the
multi-information display showing that
TRAC has been disabled even if the
switch has not been pressed
TRAC is temporary deactivated. If the infor-
mation continues to show, contact your
Lexus dealer.
■Operating conditions of hill-start assist
control
When the following four conditions are met,
the hill-start assist control will operate:
●The shift lever is in a position other than P
or N (when starting off forward/back-
ward on an upward incline).
●The vehicle is stopped.
●The accelerator pedal is not depressed.
●The parking brake is not engaged.
■Automatic system cancelation of hill-
start assist control
The hill-start assist control will turn off in any
of the following situations:
●The shift lever is shifted to P or N.
●The accelerator pedal is depressed.
●The parking brake is engaged.
●2 seconds at maximum elapsed after the
brake pedal is released
■Sounds and vibrations caused by the
ABS, brake assist, VSC, TRAC and hill-
start assist control systems
●A sound may be heard from the engine compartment when the brake pedal is
depressed repeatedly, when the hybrid
system is started or just after the vehicle
begins to move. This sound does not indi-
cate that a malfunction has occurred in
any of these systems.
●Any of the following conditions may
occur when the above systems are oper-
ating.
None of these indicates that a malfunc-
tion has occurred.
• Vibrations may be felt through the vehicle body and steering.
• A motor sound may be heard also after
the vehicle comes to a stop.
■ECB operating sound
ECB operating sound may be heard in the
following cases, but it does not indicate that
a malfunction has occurred.
●Operating sound heard from the engine
compartment when the brake pedal is
operated.
●Motor sound of the brake system heard
from the front part of the vehicle when
the driver’s door is opened.
●Operating sound heard from the engine
compartment when one or two minutes
passed after the stop of the hybrid sys-
tem.
■Active Cornering Assist operation
sounds and vibrations
When Active Cornering Assist is operated,
operation sounds and vibrations may be
generated from the brake system, but this is
not a malfunction.
■EPS operation sound
When the steering wheel is operated, a
motor sound (whirring sound) may be
heard. This does not indicate a malfunction.
■Automatic reactivation of TRAC and
VSC systems
After turning the TRAC and VSC systems
off, the systems will be automatically re-
enabled in the following situations:
●When the power switch is turned off
●If only the TRAC system is turned off, the
TRAC will turn on when vehicle speed
increases. If both the TRAC and VSC

2594-5. Using the driving support systems
4
Driving
systems are turned off, automatic re-
enabling will not occur when vehicle
speed increases.
■Secondary Collision Brake operating
conditions
The vehicle speed is approximately 6 mph
(10 km/h) or more and the airbag sensor
detects a collision. (The Secondary Colli-
sion Brake will not operate when the vehicle
speed is below approximately 6 mph [10
km/h].)
■Secondary Collision Brake automatic
cancellation
The Secondary Collision Brake is automati-
cally canceled in the following situations.
●The vehicle speed drops below approxi-
mately 6 mph (10 km/h)
●A certain amount of time elapses during
operation
●The accelerator pedal is depressed a
large amount
■Operating conditions of Active Corner-
ing Assist
The system operates in the following situa-
tions.
●TRAC/VSC can operate
●The system determines that the vehicle is
drifting to the outer side when attempting
to accelerate during cornering
●The brake pedal is released
■Reduced effectiveness of the EPS sys-
tem
The effectiveness of the EPS system is
reduced to prevent the system from over-
heating when there is frequent steering
input over an extended period of time. The
steering wheel may feel heavy as a result.
Should this occur, re frain from excessive
steering input or stop the vehicle and turn
the hybrid system off. The EPS system
should return to normal within 10 minutes.
■If a message about AWD system is
shown on the multi-information display
(AWD models)
If one of the following messages is shown on
the multi-information di splay, perform each
action.
●“AWD System Overheated Switching to
2WD Mode”
The AWD system is overheating. Reduce
load on the system by stopping the vehicle
for a while or driving the vehicle at a speed
of 6 mph (10 km/h) or more. If the message
disappears, it is possible to drive the vehicle
normally.
●“AWD System Overheated 2WD Mode
Engaged”
The AWD system has been canceled and
switched to the front-wheel drive due to
overheating. Reduce load on the system by
stopping the vehicle for a while or driving
the vehicle at a speed of 6 mph (10 km/h)
or more. If the message disappears, it is
possible to drive the vehicle normally.
●“AWD System Malfunction 2WD Mode
Engaged Visit Your Dealer”
The AWD system has been stopped and
switched to the front-wheel drive due to a
malfunction. Have your vehicle inspected
by your Lexus dealer immediately.
WARNING
■The ABS does not operate effectively
when
●The limits of tire gripping performance
have been exceeded (such as exces-
sively worn tires on a snow covered
road).
●The vehicle hydroplanes while driving
at high speed on wet or slick road.
■Stopping distance when the ABS is
operating may exceed that of normal
conditions
The ABS is not designed to shorten the
vehicle’s stopping distance. Always main-
tain a safe distance from the vehicle in
front of you, especially in the following
situations:
●When driving on dirt, gravel or snow-
covered roads

2604-5. Using the driving support systems
WARNING
●When driving with tire chains
●When driving over bumps in the road
●When driving over roads with potholes
or uneven surfaces
■TRAC/VSC may not operate effec-
tively when
Directional control and power may not
be achievable while driving on slippery
road surfaces, even if the TRAC/VSC
system is operating.
Drive the vehicle carefully in conditions
where stability and power may be lost.
■Active Cornering Assist does not
operate effectively when
●Do not rely solely upon Active Cor-
nering Assist. Active Cornering Assist
may not operate effectively when
accelerating down slopes or driving on
slippery road surfaces.
●When Active Cornering Assist fre-
quently operates, Active Cornering
Assist may temporarily stop operating
to ensure proper operation of the
brakes, TRAC, VSC.
■Hill-start assist control does not oper-
ate effectively when
●Do not overly rely on the hill-start
assist control. Hill-start assist control
may not operate effectively on steep
inclines and roads covered with ice.
●Unlike the parking brake, hill-start
assist control is not intended to hold
the vehicle stationary for an extended
period of time. Do not attempt to use
hill-start assist control to hold the vehi-
cle on an incline, as doing so may lead
to an accident.
■When the TRAC/ABS/VSC is acti-
vated
The slip indicator light flashes. Always
drive carefully. Re ckless driving may
cause an accident. Exercise particular
care when the indicator light flashes.
■When the TRAC/VSC systems are
turned off
Be especially careful and drive at a speed
appropriate to the road conditions. As
these are the systems to help ensure
vehicle stability and driving force, do not
turn the TRAC/VSC systems off unless
necessary.
■Secondary Collision Brake
Do not overly rely on the Secondary Col-
lision Brake. This system is designed to
help reduce the possibility of further
damage due to a secondary collision,
however, that effect changes according
to various conditions. Overly relying on
the system may result in death or serious
injury.
■Replacing tires
Make sure that all ti res are of the speci-
fied size, brand, tread pattern and total
load capacity. In addition, make sure that
the tires are inflated to the recom-
mended tire inflation pressure level.
The ABS, TRAC and VSC systems will
not function correctly if different tires are
installed on the vehicle.
Contact your Lexus dealer for further
information when replacing tires or
wheels.
■Handling of tires and the suspension
Using tires with any kind of problem or
modifying the suspensi on will affect the
driving assist systems, and may cause a
system to malfunction.

2614-6. Driving tips
4
Driving
4-6.Driving tips
When using Eco drive mode, the
torque corresponding to the accelera-
tor pedal depression amount can be
generated more smoothly than it is in
normal conditions. In addition, the
operation of the air conditioning sys-
tem (heating/cooling) will be mini-
mized, improving the fuel economy.
( P.255)
The Eco-friendly driving is possible by
keeping the indicate of Hybrid System
Indicator within Eco area. ( P.79, 84)
Shift the shift lever to D when stopped
at a traffic light, or driving in heavy traf-
fic, etc. Shift the shift lever to P when
parking. When using the N, there is no
positive effect on fuel consumption. In
the N, the gasoline engine operates
but electricity cannot be generated.
Also, when using the air conditioning
system, etc., the hybrid battery (trac-
tion battery) power is consumed. 
Drive your vehicle smoothly. Avoid
abrupt acceleration and decelera-
tion. Gradual acceleration and
deceleration will make more effec-
tive use of the electric motor (trac-
tion motor) without having to use
gasoline engine power.
 Avoid repeated acceleration.
Repeated acceleration consumes
hybrid battery (traction battery)
power, resulting in poor fuel con-
sumption. Battery power can be
restored by driving with the acceler-
ator pedal slightly released.
Make sure to operate the brakes gently
and in a timely manner. A greater
amount of electrical energy can be
regenerated when slowing down.
Repeated acceleration and decelera-
tion, as well as long waits at traffic
lights, will lead to bad fuel economy.
Check traffic reports before leaving
and avoid delays as much as possible.
When driving in a traffic jam, gently
release the brake pedal to allow the
vehicle to move forward slightly while
avoiding overuse of the accelerator
pedal. Doing so can help control
excessive gasoline consumption.
Hybrid vehicle driving tips
For economical and ecological
driving, pay attention to the follow-
ing points:
Using Eco drive mode
Use of Hybrid System Indicator
Shift lever operation
Accelerator pedal/brake pedal
operation
When braking
Delays