high LEXUS UX250H 2019 Service Manual

1924-5. Using the driving support systems
4-5.Using the driving support systems
■PCS (Pre-Collision System)
 P.198
■LTA (Lane Tracing Assist)
 P.205
■Automatic High Beam
 P.180
■RSA (Road Sign Assist) (if
equipped)
 P.214
■Dynamic radar cruise control with
full-speed range
 P.216 Two types of sensors, located behind
the front grille and windshield, detect
information necessary to operate the
drive assist systems.
Radar sensor
Front camera
Lexus Safety System+2.0
The Lexus Safety System+2.0 con-
sists of the following drive assist sys-
tems and contributes to a safe and
comfortable driving experience:
Driving assist system
WARNING
■Lexus Safety System+2.0
The Lexus Safety System+2.0 is
designed to operate under the assump-
tion that the driver wi ll drive safely, and is
designed to help reduce the impact to
the occupants and the vehicle in the case
of a collision or assist the driver in normal
driving conditions.
As there is a limit to the degree of recog-
nition accuracy and control performance
that this system can provide, do not
overly rely on this system. The driver is
always responsible for paying attention
to the vehicle’s surro undings and driving
safely.
Sensors
WARNING
■To avoid malfunction of the radar sen-
sor
Observe the following precautions.
Otherwise, the radar sensor may not
operate properly, possibly leading to an
accident resulting in death or serious
injury.
A
B

1974-5. Using the driving support systems
4
Driving
●In the following situations, if the situation has changed (or the vehicle has been driven for
some time) and the normal operating conditions are detected, the message will disappear
and the system will become operational.
If the message does not disappea r, contact your Lexus dealer.
When the temperature around the radar sensor is outside of the operational range, such as
when the vehicle is in the sun or in an extremely cold environment
When the front camera cannot detect objects in fr ont of the vehicle, such as when driving in
the dark, snow, or fog, or when bright lights are shining into the front camera
When the temperature around the front
camera is outside of the operational range,
such as when the vehicle is in the sun or in an
extremely cold environment
If the front camera is hot, such as after the
vehicle had been parked in the sun, use the
air conditioning system to decrease the tem-
perature around the front camera.
If a sunshade was used when the vehicle was
parked, depending on its type, the sunlight
reflected from the surface of the sunshade
may cause the temperature of the front cam-
era to become excessively high.
If the front camera is cold, such after the
vehicle is parked in an extremely cold envi-
ronment, use the air conditioning system to
increase the temperature around the front
camera.
The area in front of the front camera is
obstructed, such as when the hood is open
or a sticker is attached to the part of the
windshield in front of the front camera.
Close the hood, remove the sticker, etc. to
clear the obstruction.
SituationActions

1984-5. Using the driving support systems
The system can detect the following:
Vehicles
 Bicyclists
 Pedestrians
■Pre-collision warning
When the system determines that the
possibility of a frontal collision is high, a
buzzer will sound and a warning mes-
sage will be displayed on the multi-
information display to urge the driver to take evasive action.
■Pre-collision brake assist
When the system determines that the
possibility of a frontal collision is high,
the system applies greater braking
force in relation to how strongly the
brake pedal is depressed.
■Pre-collision braking
If the system determines that the possi-
bility of a frontal collision is extremely
high, the brakes are automatically
applied to help avoid the collision or
reduce the impact of the collision.
PCS (Pre-Collision System)
The pre-collision system uses a
radar sensor and front camera to
detect objects ( P.198) in front of
the vehicle. When the system
determines that the possibility of a
frontal collision with an object is
high, a warning operates to urge
the driver to take evasive action
and the potential brake pressure is
increased to help the driver avoid
the collision. If the system deter-
mines that the possibility of a frontal
collision with an object is extremely
high, the brakes are automatically
applied to help avoid the collision or
help reduce the impact of the colli-
sion.
The pre-collision system can be dis-
abled/enabled and the warning tim-
ing can be changed. ( P.200)
Detectable objects
System functions
WARNING
■Limitations of the pre-collision system
●The driver is solely responsible for safe
driving. Always drive safely, taking
care to observe your surroundings. Do
not use the pre-collision system
instead of normal braking operations
under any circumstances. This system
will not prevent collisions or lessen col-
lision damage or injury in every situa-
tion. Do not overly rely on this system.
Failure to do so may lead to an acci-
dent, resulting in death or serious
injury.

2004-5. Using the driving support systems
■Enabling/disabling the pre-colli-
sion system
The pre-collision system can be
enabled/disabled on ( P.87) of
the multi-information display.
The system is automatically enabled each
time the power switch is turned to ON.
If the system is disabled, the PCS warn-
ing light will turn on and a message will
be displayed on the multi-information
display.
■Changing the pre-collision warn-
ing timing
The pre-collision warning timing can
be changed on ( P.87) of the
multi-information display.
The warning timing setting is retained
when the power switch is turned off. How-
ever, if the pre-collisio n system is disabled
and re-enabled, the operation timing will
return to the default setting (middle).
1Early
2
Middle
This is the default setting.
3Late
■Operational conditions
The pre-collision system is enabled and the system determines that the possibility of a frontal
collision with a detect ed object is high.
WARNING
●When the tires are very worn
●When tires of a size other than speci-
fied are installed
●When tire chains are installed
●When a compact spare tire or an
emergency tire puncture repair kit is
used
●If equipment (snow plow, etc.) that may
obstruct the radar sensor or front cam-
era is temporarily installed to the vehi-
cle
Changing settings of the pre-col-
lision system

2034-5. Using the driving support systems
4
Driving
that may contact your vehicle, such as
thick grass, tree branches, or a banner
• When driving through steam or smoke
• When driving near an object that reflects
radio waves, such as a large truck or
guardrail
• When driving near a TV tower, broad- casting station, electric power plant, or
other location where strong radio waves
or electrical noise may be present
■Situations in which the system may not
operate properly
●In some situations such as the following,
an object may not be detected by the
radar sensor and front camera, prevent-
ing the system from operating properly:
• When a detectable object is approaching
your vehicle
• When your vehicle or a detectable object
is wobbling
• If a detectable object makes an abrupt maneuver (such as sudden swerving,
acceleration or deceleration)
• When your vehicle approaches a detect- able object rapidly
• When a detectable object is not directly
in front of your vehicle
• When a detectable object is near a wall, fence, guardrail, manhole cover, vehicle,
steel plate on the road, etc.
• When a detectable object is under a structure
•When part of a detect able object is hid-
den by an object, such as large baggage, an umbrella, or guardrail
• When multiple dete ctable objects are
close together
• If the sun or other light is shining directly on a detectable object
• When a detectable object is a shade of
white and looks extremely bright
• When a detectable ob ject appears to be
nearly the same color or brightness as its
surroundings
• If a detectable object cuts or suddenly emerges in front of your vehicle
• When the front of your vehicle is hit by water, snow, dust, etc.
• When a very bright light ahead, such as
the sun or the head lights of oncoming
traffic, shines direct ly into the front cam-
era
• When approaching the side or front of a vehicle ahead
• If a vehicle ahead is a motorcycle
• If a vehicle ahead is narrow, such as a per-
sonal mobility vehicle
• If a preceding vehicle has a small rear
end, such as an unloaded truck
• If a preceding vehicle has a low rear end, such as a low bed trailer
• If a vehicle ahead has extremely high ground clearance
• If a vehicle ahead is carrying a load which protrudes past its rear bumper
• If a vehicle ahead is irregularly shaped,
such as a tractor or side car
• If a vehicle ahead is a child sized bicycle, a bicycle that is carrying a large load, a

2044-5. Using the driving support systems
bicycle ridden by more than one person,
or a uniquely shaped bicycle (bicycle with
a child seat, tandem bicycle, etc.)
• If a pedestrian/or the riding height of a bicyclist ahead is shorter than approxi-
mately 3.2 ft. (1 m) or taller than approxi-
mately 6.5 ft. (2 m)
• If a pedestrian/bicyclist is wearing over- sized clothing (a rain coat, long skirt,
etc.), making their silhouette obscure
• If a pedestrian is bending forward or squatting or bicyclist is bending forward
• If a pedestrian/bicyclist is moving fast
• If a pedestrian is pushing a stroller, wheel- chair, bicycle or other vehicle
• When driving in incl ement weather such
as heavy rain, fog, snow or a sandstorm
• When driving through steam or smoke
• When the surrounding area is dim, such
as at dawn or dusk, or while at night or in
a tunnel, making a detectable object
appear to be nearly the same color as its
surroundings
• When driving in a place where the sur-
rounding brightness changes suddenly,
such as at the entrance or exit of a tunnel
• After the hybrid system has started the
vehicle has not been driven for a certain
amount of time
• While making a left/right turn and for a
few seconds after makin g a left/right turn
• While driving on a curve and for a few seconds after driving on a curve
• If your vehicle is skidding
• If the front of the vehicle is raised or low- ered
• If the wheels are misaligned
• If a wiper blade is blocking the front cam- era
• The vehicle is being driven at extremely high speeds
• When driving on a hill
• If the radar sensor or front camera is mis-
aligned●In some situations su ch as the following,
sufficient braking force may not be
obtained, preventing the system from
performing properly:
• If the braking functions cannot operate to their full extent, such as when the brake
parts are extremely cold, extremely hot,
or wet
• If the vehicle is not properly maintained
(brakes or tires are excessively worn,
improper tire inflation pressure, etc.)
• When the vehicle is being driven on a
gravel road or other slippery surface
■If VSC is disabled
●If VSC is disabled ( P.257), the pre-col-
lision brake assist and pre-collision brak-
ing functions are also disabled.
●The PCS warning light will turn on and
“VSC Turned OFF Pre-Collision Brake
System Unavailable” will be displayed on
the multi-information display.

2054-5. Using the driving support systems
4
Driving
LTA (Lane Tracing Assist)
When driving on highways and
freeways with white (yellow) lane
lines, this function alerts the driver
when the vehicle might depart from
its lane or course
* and provides
assistance by operating the steer-
ing wheel to keep the vehicle in its
lane or course
*. Furthermore, the
system provides steering assistance
when dynamic radar cruise control
with full-speed range is operating
to keep the vehicle in its lane.
The LTA system recognizes white
(yellow) lane lines or a course
*
using the front camera. Addition-
ally, it detects preceding vehicles
using the front camera and radar.
*: Boundary between asphalt and the side of the road, such as grass, soil, or
a curb
WARNING
■Before using LTA system
●Do not rely solely upon the LTA sys-
tem. The LTA system does not auto-
matically drive the vehicle or reduce
the amount of attention that must be
paid to the area in front of the vehicle.
The driver must always assume full
responsibility for driving safely by pay-
ing careful attention to the surround-
ing conditions and operating the
steering wheel to correct the path of
the vehicle. Also, the driver must take
adequate breaks when fatigued, such
as from driving for a long period of
time.
●Failure to perform appropriate driving
operations and pay careful attention
may lead to an accident, resulting in
death or serious injury.
●When not using the LTA system, use
the LTA switch to turn the system off.
■Situations unsuitable for LTA system
In the following situations, use the LTA
switch to turn the system off. Failure to do
so may lead to an accident, resulting in
death or serious injury.
●Vehicle is driven on a road surface
which is slippery due to rainy weather,
fallen snow, freezing, etc.
●Vehicle is driven on a snow-covered
road.
●White (yellow) lines are difficult to see
due to rain, snow, fog, dust, etc.
●Vehicle is driven in a temporary lane or
restricted lane due to construction
work.
●Vehicle is driven in a construction
zone.
●A spare tire, tire chains, etc. are
equipped.
●When the tires have been excessively
worn, or when the tire inflation pres-
sure is low.

2064-5. Using the driving support systems
WARNING
●When tires of a size other than speci-
fied are installed.
●Vehicle is driven in traffic lanes other
than that highways and freeways.
●During emergency towing
■Preventing LTA system malfunctions
and operations performed by mistake
●Do not modify the headlights or place
stickers, etc. on the surface of the
lights.
●Do not modify the suspension etc. If
the suspension etc. needs to be
replaced, contact your Lexus dealer.
●Do not install or place anything on the
hood or grille. Also, do not install a
grille guard (bull bars, kangaroo bar,
etc.).
●If your windshield needs repairs, con-
tact your Lexus dealer.
■Conditions in which functions may
not operate properly
In the following situations, the functions
may not operate properly and the vehicle
may depart from its lane. Drive safely by
always paying careful attention to your
surroundings and operate the steering
wheel to correct the path of the vehicle
without relying solely on the functions.
●When the follow-up cruising display is
displayed ( P.210) and the preceding
vehicle changes lanes. (Your vehicle
may follow the preceding vehicle and
also change lanes.)
●When the follow-up cruising display is
displayed ( P.210) and the preceding
vehicle is swaying. (Your vehicle may
sway accordingly and depart from the
lane.)
●When the follow-up cruising display is
displayed ( P.210) and the preceding
vehicle departs from its lane. (Your
vehicle may follow the preceding vehi-
cle and depart from the lane.)
●When the follow-up cruising display is
displayed ( P.210) and the preceding
vehicle is being driven extremely close
to the left/right lane line. (Your vehicle
may follow the preceding vehicle and
depart from the lane.)
●Vehicle is being driven around a sharp
curve.
●Objects or patterns that could be mis-
taken for white (yellow) lines are pres-
ent on the side of the road (guardrails,
curbs, reflective poles, etc.).

2084-5. Using the driving support systems
■Lane departure alert function
When the system determines that the
vehicle might depart from its lane or
course
*, a warning is displayed on the
multi-information display, and either a
warning buzzer will sound or the steer-
ing wheel will vibrate to alert the driver.
When the warning buzzer sounds or the
steering wheel vibrates, check the area
around your vehicle and carefully operate
the steering wheel to move the vehicle
back to the center of the lane.
Vehicles with Blind Spot Monitor: When
the system determines that the vehicle
might depart from its lane and that the pos-
sibility of a collision with an overtaking
vehicle in the adjacent lane is high, the lane
departure alert will operate even if the turn
signals are operating.
*: Boundary between asphalt and the side of the road, such as grass, soil, or a curb
■Steering assist function
When the system determines that the
vehicle might depart from its lane or
course
*, the system provides assis-
tance as necessary by operating the
steering wheel in small amounts for a
short period of time to keep the vehicle
in its lane.
If the system detects that the steering
wheel has not been operated for a fixed
amount of time or the steering wheel is not
being firmly gripped, a warning is displayed
on the multi-informat ion display and the
function is temporarily canceled.
Vehicles with Blind Spot Monitor: When
the system determines that the vehicle
might depart from its lane and that the pos-
sibility of a collision with an overtaking
vehicle in the adjacent lane is high, the
steering assist function will operate even if
the turn signals are operating.
*: Boundary between asphalt and the side of the road, such as grass, soil, or a curb
WARNING
●The vehicle is affected by wind from a
vehicle driven in a nearby lane.
●The vehicle has just changed lanes or
crossed an intersection.
●Tires which differ by structure, manu-
facturer, brand or tread pattern are
used.
●Snow tires, etc. are equipped.
●The vehicle is being driven at
extremely high speeds.
Functions included in LTA system

2164-5. Using the driving support systems
currently traveled lane, such a sign exists
directly after a freeway branches, or in an
adjacent lane just before merging.
●Stickers are attached to the rear of the
preceding vehicle.
●A sign resembling a system compatible
sign is recognized.
●Side road speed signs may be detected
and displayed (if positioned in sight of the
front camera) while the vehicle is travel-
ing on the main road.
●Roundabout exit road speed signs may
be detected and displayed (if positioned
in sight of the front camera) while travel-
ing on a roundabout.
●The front of the vehicle is raised or low-
ered due to the carried load.
●The surrounding brightness is not suffi-
cient or changes suddenly.
●When a sign intended for trucks, etc. is
recognized.
●Vehicles with navigation system: The
speed information displayed on the
meter and that displayed on the naviga-
tion system may be different due to the
navigation system using map data.
■Speed limit sign display
If the power switch was last turned off while
a speed limit sign wa s displayed on the
multi-information display, the same sign dis-
plays again when the power switch is turned
to ON.
■Customization
Some functions can be customized. (Cus-
tomizable features: P.442)
■Meter display
Multi-information display
Set speed
Indicators
Dynamic radar cruise con-
trol with full-speed range
In vehicle-to-vehicle distance con-
trol mode, the ve hicle automati-
cally accelerates, decelerates and
stops to match the speed changes
of the preceding vehicle even if the
accelerator pedal is not depressed.
In constant speed control mode,
the vehicle runs at a fixed speed.
Use the dynamic radar cruise con-
trol with full-speed range on free-
ways and highways.
 Vehicle-to-vehicle distance con-
trol mode ( P.219)
 Constant speed control mode
( P.223)
System Components
A
B
C