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Toyota Prius Prime (2022 year). Manual in english - page 24

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5-5. Using the driving support systems

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■

Object detection function

■

Cancelation of the pre-collision braking

If either of the following occur while the pre-collision braking function is oper-
ating, it will be canceled:

●

The accelerator pedal is depressed strongly.

●

The steering wheel is turned sharply or abruptly.

■

Conditions under which the system may operate even if there is no pos-
sibility of a collision

●

In some situations such as the following, the system may determine that
there is a possibility of a frontal collision and operate.
• When passing a detectable object, etc.
• When changing lanes while overtaking a detectable object, etc.

• When rapidly closing on a detectable object, etc.
• When approaching objects on the roadside, such as detectable objects,

guardrails, utility poles, trees, or walls

The  system  detects  objects  based  on
their  size,  profile,  motion,  etc.  However,
an object may not be detected depending
on  the  surrounding  brightness  and  the
motion,  posture,  and  angle  of  the
detected  object,  preventing  the  system
from operating properly. (



P. 387)

The illustration shows an image of detect-
able objects.

• When approaching a detectable

object in an adjacent lane or on the
roadside, such as when changing the
course of travel or driving on a wind-
ing road

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5-5. Using the driving support systems

• When there are patterns or paint in front of your vehicle that may be mis-

taken for a detectable object

• When the front of your vehicle is hit by water, snow, dust, etc.

• When a detectable object approaches very close and then stops before

entering the path of your vehicle

• If the front of your vehicle is raised or lowered, such as when on an

uneven or undulating road surface

• When driving on a road surrounded by a structure, such as in a tunnel or

on an iron bridge

• When there is a metal object (manhole cover, steel plate, etc.), steps, or a

protrusion in front of your vehicle

• When approaching an electric toll gate barrier, parking area barrier, or

other barrier that opens and closes

• When using an automatic car wash

• When there is a detectable object or

other object by the roadside at the
entrance of a curve

• When overtaking a detectable object

that is changing lanes or making a
right/left turn

• When passing a detectable object in

an oncoming lane that is stopped to
make a right/left turn

• When passing under an object (road

sign, billboard, etc.)

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5-5. Using the driving support systems

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• 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, broadcasting 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, preventing 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 swerv-

ing, acceleration or deceleration)

• When your vehicle approaches a detectable object rapidly

• 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 detectable object is hidden by an object, such as large

baggage, an umbrella, or guardrail

• When multiple detectable 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 object appears to be nearly the same color or bright-

ness 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 headlights of

oncoming traffic, shines directly into the front camera

• When approaching the side or front of a vehicle ahead
• If a vehicle ahead is a motorcycle

• When driving through or under

objects that may contact your vehicle,
such as thick grass, tree branches, or
a banner

• When a detectable object is not

directly in front of your vehicle

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5-5. Using the driving support systems

• If a vehicle ahead is narrow, such as a personal mobility vehicle
• If a preceding vehicle has a small rear end, such as an unloaded truck

• 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 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

approximately 3.2 ft. (1 m) or taller than approximately 6.5 ft. (2 m)

• If a pedestrian/bicyclist is wearing oversized clothing (a rain coat, long

skirt, etc.), making their silhouette obscure

• If a pedestrian is bending forward or squatting or bicyclist is bending for-

ward

• If a pedestrian/bicyclist is moving fast
• If a pedestrian is pushing a stroller, wheelchair, bicycle or other vehicle
• When driving in inclement 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 surrounding brightness changes sud-

denly, 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 making 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 a preceding vehicle has a low rear

end, such as a low bed trailer

• If a vehicle ahead has extremely high

ground clearance

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5-5. Using the driving support systems

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• If the wheels are misaligned
• If a wiper blade is blocking the front camera
• The vehicle is being driven at extremely high speeds
• When driving on a hill
• If the radar sensor or front camera is misaligned

●

In some situations such 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 sur-

face

■

If VSC is disabled

●

If VSC is disabled (



P. 498), the pre-collision brake assist and pre-collision

braking 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.

• If the front of the vehicle is raised or

lowered

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5-5. Using the driving support systems

LTA (Lane Tracing Assist)

While driving on a road with clear white (yellow) lane lines, the LTA
system warns the driver if the vehicle may deviate from the current
lane or course

, and also can slightly operate the steering wheel to

help avoid deviation from the lane or course

. Also, while the dynamic

radar cruise control with full-speed range is operating, this system will
operate the steering wheel to maintain the vehicle’s lane position.
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

Summary of functions

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5-5. Using the driving support systems

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WARNING

■

Before using LTA system

●

Do not rely solely upon the LTA system. 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 paying 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.

●

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 Toyota 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, contact your Toyota dealer.

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5-5. Using the driving support systems

WARNING

■

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. 400) and the pre-

ceding vehicle is swaying. (Your vehicle may sway accordingly and depart
from the lane.)

●

When the follow-up cruising display is displayed (



P. 400) and the pre-

ceding vehicle departs from its lane. (Your vehicle may follow the preced-
ing vehicle and depart from the lane.)

●

When the follow-up cruising display is displayed (



P. 400) and the pre-

ceding 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.

●

When the follow-up cruising display is
displayed (



P. 400) and the preceding

vehicle changes lanes. (Your vehicle
may follow the preceding vehicle and
also change lanes.)

●

Objects or patterns that could be mis-
taken for white (yellow) lines are pres-
ent on the side of the road (guardrails,
reflective poles, etc.).

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WARNING

●

There are shadows on the road that run parallel with, or cover, the white
(yellow) lines.

●

The vehicle is driven in an area without white (yellow) lines, such as in
front of a tollgate or checkpoint, or at an intersection, etc.

●

The white (yellow) lines are cracked, “Botts’ dots”, “Raised pavement
marker” or stones are present.

●

The white (yellow) lines cannot be seen or are difficult to see due to sand,
etc.

●

The vehicle is driven on a road surface that is wet due to rain, puddles,
etc.

●

The traffic lines are yellow (which may be more difficult to recognize than
lines that are white).

●

The white (yellow) lines cross over a curb, etc.

●

The vehicle is driven on a bright surface, such as concrete.

●

If the edge of the road is not clear or straight.

●

The vehicle is driven on a surface that is bright due to reflected light, etc.

●

Vehicle is driven where the road
diverges, merges, etc.

●

Repair marks of asphalt, white (yellow)
lines, etc. are present due to road
repair.

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5-5. Using the driving support systems

WARNING

●

The vehicle is driven in an area where the brightness changes suddenly,
such as at the entrances and exits of tunnels, etc.

●

Light from the headlights of an oncoming vehicle, the sun, etc. enters the
camera.

●

The vehicle is driven on a slope.

●

The vehicle is driven on a road which tilts left or right, or a winding road.

●

The vehicle is driven on an unpaved or rough road.

●

The traffic lane is excessively narrow or wide.

●

The vehicle is extremely tilted due to carrying heavy luggage or having
improper tire pressure.

●

The distance to the preceding vehicle is extremely short.

●

The vehicle is moving up and down a large amount due to road conditions
during driving (poor roads or road seams).

●

When driving in a tunnel or at night with the headlights off or when a head-
light is dim due to its lens being dirty or it being misaligned.

●

The vehicle is struck by a crosswind.

●

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, manufacturer, brand or tread pattern are
used.

●

When tires of a size other than specified are installed.

●

Snow tires, etc. are equipped.

●

The vehicle is being driven at extremely high speeds.

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■

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 a
warning buzzer will sound to
alert the driver.

When  the  warning  buzzer
sounds,  check  the  area  around
your vehicle and carefully  oper-
ate  the  steering  wheel  to  move
the vehicle back to the center of
the lane.

: Boundary between asphalt and the side of the road, such as grass, soil, or

a curb

Functions included in LTA system

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5-5. Using the driving support systems

■

Steering assist function

When  the  system  determines
that  the  vehicle  might  depart
from  its  lane  or  course

, the

system provides assistance as
necessary by operating the
steering

wheel

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-infor-
mation  display  and  the  function
is temporarily canceled.

: Boundary between asphalt and the side of the road, such as grass, soil, or

a curb

■

Vehicle sway warning function

When  the  vehicle  is  swaying
within  a  lane,  the  warning
buzzer  will  sound  and  a  mes-
sage  will  be  displayed  on  the
multi-information display to alert
the driver.

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■

Lane centering function

This  function  is  linked  with
dynamic  radar  cruise  control
with  full-speed  range  and  pro-
vides  the  required  assistance
by operating the steering wheel
to keep the vehicle in its current
lane.

When dynamic radar cruise con-
trol  with  full-speed  range  is  not
operating,  the  lane  centering
function does not operate.
In  situations  where  the  white
(yellow) lane lines are difficult to
see  or  are  not  visible,  such  as
when  in  a  traffic  jam,  this  func-
tion will operate to help follow a
preceding vehicle by monitoring
the  position  of  the  preceding
vehicle.
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-information display and the function
is temporarily canceled.

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5-5. Using the driving support systems

Press the LTA switch to turn the
LTA system on.

The LTA indicator illuminates and a
message is displayed on the multi-
information display.
Press the LTA switch again to turn
the LTA system off.
When the LTA system is turned on
or off, operation of the LTA system
continues in the same condition
the next time the hybrid system is
started.

Turning LTA system on

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5-5. Using the driving support systems

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LTA indicator
The illumination condition of the
indicator  informs  the  driver  of
the system operation status.
Illuminated  in  green:  LTA  sys-
tem is operating.
Flashing  in  orange:  Lane
departure alert function is oper-
ating.
Steering  control  indicator  and  operation  display  of  steering  wheel
operation support
When that steering wheel assistance of the steering assist function
or lane centering function is operating, the indicator illuminates and
the operation display on the multi-information display is turned on.
Lane departure alert function display
Displayed  when  the  multi-information  display  is  switched  to  the
driving assist system information screen.

: Boundary between asphalt and the side of the road, such as grass, soil, or

a curb

Indications on combination meter



Inside of displayed lines is
white



Inside of displayed lines is
black

Indicates that the system is recog-
nizing white (yellow) lines or a
course

When

the

vehicle

departs  from  its  lane,  the  white
line  displayed  on  the  side  the
vehicle  departs  from  flashes
orange.

Indicates that the system is not
able to recognize white (yellow)
lines or a course

or is temporar-

ily canceled.

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5-5. Using the driving support systems

Follow-up cruising display

Displayed when the multi-information display is switched to the driving
assist system information screen.
Indicates that steering assist of the lane centering function is operating by
monitoring the position of a preceding vehicle.
When the follow-up cruising display is displayed, if the preceding vehicle
moves, your vehicle may move in the same way. Always pay careful atten-
tion to your surroundings and operate the steering wheel as necessary to
correct the path of the vehicle and ensure safety.

■

Operation conditions of each function

●

Lane departure alert function
This function operates when all of the following conditions are met.
• LTA is turned on.
• Vehicle speed is approximately 32 mph (50 km/h) or more.

• System recognizes white (yellow) lane lines or a course

. (When a white

[yellow] line or course

is recognized on only one side, the system will

operate only for the recognized side.)

• Width of traffic lane is approximately 9.8 ft. (3 m) or more.
• Turn signal lever is not operated.
• Vehicle is not being driven around a sharp curve.
• No system malfunctions are detected. (



P. 404)

: The function operates even if the vehicle speed is less than approxi-

mately 32 mph (50 km/h) when the lane centering function is operating.

: Boundary between asphalt and the side of the road, such as grass, soil,

or a curb

●

Steering assist function
This function operates when all of the following conditions are met in addi-
tion to the operation conditions for the lane departure alert function.

• Setting for

(“LTA Steering Assist Mode”) in

of the multi-

information display is set to “On”. (



P. 220)

• Vehicle is not accelerated or decelerated by a fixed amount or more.
• Steering wheel is not operated with a steering force level suitable for

changing lanes.

• ABS, VSC, TRAC and PCS are not operating.
• TRAC or VSC is not turned off.
• Hands off steering wheel warning is not displayed. (



P. 403)

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