2019 LEXUS UX250H brake sensor

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

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,

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

3897-2. Steps to take in an emergency
7
When trouble arises
■Parking brake indicator
■Brake hold operated indicator (warning buzzer)
■Intuitive parking assist OFF indicator (warning buzzer)
■RCTA OFF indicator (warning buzzer)
Warning lightDetails/Actions
(flashes)(U.S.A.)
or
(flashes)
(Canada)
Indicates a malfunction in the parking brake system
 Have the vehicle inspected by your Lexus dealer immediately.
Warning lightDetails/Actions
(flashes)
Indicates a malfunction in the brake hold system
Have the vehicle inspected by your Lexus dealer immediately.
Warning lightDetails/Actions
(flashes)
When a buzzer sounds:
Indicates a malfunctio n in the intuitive parking assist function
 Have the vehicle inspected by your Lexus dealer immediately.
When a buzzer does not sound:
Indicates that the system is temporarily unavailable, possibly due to a
sensor being dirty or covered with ice, etc.
 Follow the instructions displayed on the multi-information display.
(  P.234)
Warning lightDetails/Actions
(flashes)
Indicates a malfunction in the RCTA (Rear Cross Traffic Alert) function
 Have the vehicle inspected by your Lexus dealer immediately.

3907-2. Steps to take in an emergency
■PKSB OFF indicator (warning buzzer)
■Low fuel level warning light
■Driver’s and front passenger’s seat belt reminder light (warning buzzer)*
*: Driver’s seat belt warning buzzer:
The driver’s seat belt warning buzzer sounds to al ert the driver that his or her seat belt is not
fastened. Once the power switch is turned to ON, the buzzer sounds for 6 seconds. If the
vehicle reaches a speed of 12 mph (20 km/h), the buzzer sounds once. If the seat belt is still
unfastened after 24 seco nds, the buzzer will sound intermitte ntly for 6 seconds. Then, if the
seat belt is still unfastened, the buzzer will sound in a different tone for 90 more seconds.
Front passenger’s seat belt warning buzzer:
The front passenger’s seat belt warning buzzer sounds to alert the front passenger that his
or her seat belt is not fastened. The buzzer sounds once if the vehicle reaches a speed of 12
mph (20 km/h). If the seat belt is still unfastened after 24 seconds, the buzzer will sound
intermittently for 6 seconds. Th en, if the seat belt is still unfastened, the buzzer will sound in
a different tone for 90 more seconds.
Warning lightDetails/Actions
(flashes)
When a buzzer sounds:
Indicates a malfunction in the PK SB (Parking Support Brake) system
 Have the vehicle inspected by your Lexus dealer immediately.
When a buzzer does not sound:
Indicates that the system is temporarily unavailable, possibly due to a
sensor being dirty or covered with ice, etc.
 Follow the instructions displayed on the multi-information display.
(  P.246)
Warning lightDetails/Actions
Indicates that remaining fuel is approx imately 1.6 gal. (6.0L, 1.3 Imp.gal.)
or less
 Refuel the vehicle.
Warning lightDetails/Actions
Warns the driver and/or front passe nger to fasten their seat belts
 Fasten the seat belt.
If the front passenger’s seat is occupied, the front passenger’s seat
belt also needs to be fastened to make the warning light (warning
buzzer) turn off.

3937-2. Steps to take in an emergency
7
When trouble arises
bag sensor assembly, front impact sensors,
side impact sensors (front door), side
impact sensors (front), side impact sensors
(rear), driver’s seat position sensor, driver’s
seat belt buckle switch, front passenger
occupant classification system (ECU and
sensors), rear seat belt buckle switches (if
equipped), “AIR BAG ON” indicator light,
“AIR BAG OFF” indicator light, front pas-
senger’s seat belt buckle switch, seat belt
pretensioners, airbags, interconnecting wir-
ing and power sources. (P.31)
■Electric power steering system warning
light (warning buzzer)
When the 12-volt battery charge becomes
insufficient or the voltage temporarily
drops, the electric po wer steering system
warning light may come on and the warning
buzzer may sound.
■When the tire pressure warning light
comes on
Inspect the tires to check if a tire is punc-
tured.
If a tire is punctured: P.399
If none of the tires are punctured:
Turn the power switch off then turn it to ON.
Check if the tire pressure warning light
comes on or blinks.
If the tire pressure warning light blinks for
approximately 1 minute then stays on
There may be a malfunction in the tire pres-
sure warning system. Have the vehicle
inspected by your Lexus dealer immedi-
ately.
If the tire pressure warning light comes
on
1
After the temperature of the tires has
lowered sufficiently, check the inflation
pressure of each tire and adjust them to
the specified level.
2
If the warning light does not turn off
even after several minutes have
elapsed, check that the inflation pres-
sure of each tire is at the specified level
and perform initialization. ( P.351)
■The tire pressure warning light may
come on due to natural causes
The tire pressure warning light may come
on due to natural causes such as natural air leaks and tire inflation pressure changes
caused by temperature. In this case, adjust-
ing the tire inflation pressure will turn off the
warning light (after a few minutes).
■Conditions that the tire pressure warn-
ing system may not function properly
 P.348
WARNING
■If both the ABS and the brake system
warning lights remain on
Stop your vehicle in a safe place immedi-
ately and contact your Lexus dealer.
The vehicle will become extremely
unstable during braking, and the ABS
system may fail, which could cause an
accident resulting in death or serious
injury.
■When the electric power steering
system warning light comes on
When the light comes on yellow, the
assist to the power st eering is restricted.
When the light comes on red, the assist
to the power steering is lost and handling
operations of the steering wheel become
extremely heavy.
When steering wheel operations are
heavier than usual, grip the steering
wheel firmly and operate it using more
force than usual.
■If the tire pressure warning light
comes on
Be sure to observe the following precau-
tions.
Failure to do so could cause a loss of
vehicle control and result in death or
serious injury.
●Decelerate to the lowest appropriate
speed as soon as possible. Do not
drive over 50 mph (80 km/h).
●Check and adjust the tire inflation
pressure immediately.

461What to do if... (Troubleshooting)
If you cannot release the shift lever
by depressing the brake pedal with
the power switch in ON (P.168)
 It is locked automatically to prevent
theft of the vehicle. ( P.163)
 Is the window lock switch pressed?
The power window except for the
one at the driver’s seat cannot be
operated if the window lock switch
is pressed. ( P.146)
 The auto power off function will be
operated if the vehicle is left in ACC
or ON (the hybrid system is not
operating) for a period of time.
( P.164)
 The seat belt reminder light is flash-
ing
Are the driver and the front passen-
ger wearing the seat belts?
( P.390)
 The parking brake indicator is on
Is the parking brake released?
( P.172) Depending on the situation, other
types of warning buzzer may also
sound. (
P.386, 395)
 Did anyone inside the vehicle open
a door during setting the alarm?
The sensor detects it and the alarm
sounds. ( P.71)
To stop the alarm, turn the power
switch to ON or start the hybrid sys-
tem.
 Is the message displayed on the
multi-information display?
Check the message on the multi-
information display. ( P.395)
 When a warning light turns on or a
warning message is displayed, refer
to P.386, 395.
 Slow down the vehicle, drive with
extra caution, and take your vehicle
to the nearest Lexus dealer or
authorized tire dealer as soon as
The steering wheel cannot be
turned after the hybrid system is
stopped
The windows do not open or
close by operating the power
window switches
The power switch is turned off
automatically
A warning buzzer sounds during
drivingAn alarm is activated and the
horn sounds
A warning buzzer sounds when
leaving the vehicle
A warning light turns on or a
warning message is displayed
When a problem has occurred
If you have a flat tire