Toyota Prius (2023 year). Manual in english - page 19

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4-5. Using the driving support systems

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, “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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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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4-5. 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 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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■

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 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-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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4-5. Using the driving support systems

■

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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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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4-5. Using the driving support systems

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.

Indications on combination meter

1

2

3

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*

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

a curb

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.



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.

4

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4-5. Using the driving support systems

■

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 50 km/h (32 mph) or more.

*

1

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

*

2

. (When a white

[yellow] line or course

*

2

 is recognized on only one side, the system will

operate only for the recognized side.)

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



P. 322)

*

1

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

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

*

2

: 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. 127)

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



P. 321)

●

Vehicle sway warning function
This function operates when all of the following conditions are met.

• Setting for 

 (“Lane Sway Warning Status”) in 

 of the multi-

information display is set to “On”. (



P. 127)

• Vehicle speed is approximately 50 km/h (32 mph) or more.
• Width of traffic lane is approximately 3 m (9.8 ft.) or more.
• No system malfunctions are detected. (



P. 322)

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●

Lane centering function
This function operates when all of the following conditions are met.
• LTA is turned on.
• Setting for 

 (“LTA Steering Assist Mode”) and 

 (“LTA

Center Trace On/Off”) in 

 of the multi-information display are set to

“On”. (



P. 127)

• This function recognizes white (yellow) lane lines or the position of a pre-

ceding vehicle (except when the preceding vehicle is small, such as a
motorcycle).

• The dynamic radar cruise control with full-speed range is operating in

vehicle-to-vehicle distance control mode.

• Width of traffic lane is approximately 3 to 4 m (10 to 13 ft.).
• Turn signal lever is not operated.
• Vehicle is not being driven around a sharp curve.
• No system malfunctions are detected. (



P. 322)

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

changing lanes.

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



P. 321)

• The vehicle is being driven in the center of a lane.
• Steering assist function is not operating.

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4-5. Using the driving support systems

■

Temporary cancelation of functions

●

When operation conditions are no longer met, a function may be temporarily
canceled. However, when the operation conditions are met again, operation
of the function is automatically restored. (



P. 318)

●

If the operation conditions (



P. 319) are no longer met while the lane cen-

tering function is operating, the buzzer may sound to indicate that the func-
tion has been temporarily canceled.

■

Steering assist function/lane centering function

●

Depending on the vehicle speed, lane departure situation, road conditions,
etc., the driver may not feel the function is operating or the function may not
operate at all.

●

The steering control of the function is overridden by the driver’s steering
wheel operation.

●

Do not attempt to test the operation of the steering assist function.

■

Lane departure alert function

●

The warning buzzer may be difficult to hear due to external noise, audio
playback, etc.

●

If the edge of the course

*

 is not clear or straight, the lane departure alert

function may not operate.

●

Do not attempt to test the operation of the lane departure alert function.

*

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

a curb

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■

Hands off steering wheel warning

●

When the system determines that the driver is driving without holding the
steering wheel while the system is operating
If the driver continues to keep their hands off of the steering wheel, the
buzzer sounds, the driver is warned and the function is temporarily can-
celed. This warning also operates in the same way when the driver continu-
ously operates the steering wheel only a small amount.

●

When the system determines that the vehicle may deviate from the lane
while driving around a curve while the lane centering function is operating
Depending on the vehicle condition and road conditions, the warning may
not operate. Also, if the system determines that the vehicle is driving
around a curve, warnings will occur earlier than during straight-lane driving.

●

When the system determines that the driver is driving without holding the
steering wheel while the steering wheel assist of the steering assist function
is operating.
If the driver continues to keep their hands off of the steering wheel and the
steering wheel assist is operating, the buzzer sounds and the driver is
warned. Each time the buzzer sounds, the continuing time of the buzzer
becomes longer.

■

Vehicle sway warning function

In the following situations, a warning mes-
sage urging the driver to hold the steering
wheel and the symbol shown in the illus-
tration are displayed on the multi-informa-
tion display to warn the driver. The
warning stops when the system deter-
mines that the driver holds the steering
wheel. Always keep your hands on the
steering wheel when using this system,
regardless of warnings.

When the system determines that the
vehicle is swaying while the vehicle sway
warning function is operating, a buzzer
sounds and a warning message urging
the driver to rest and the symbol shown in
the illustration are simultaneously dis-
played on the multi-information display.
Depending on the vehicle and road condi-
tions, the warning may not operate.

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4-5. Using the driving support systems

■

Warning message

If the following warning message is displayed on the multi-information display
and the LTA indicator illuminates in orange, follow the appropriate trouble-
shooting procedure. Also, if a different warning message is displayed, follow
the instructions displayed on the screen.

●

“LTA Malfunction Visit Your Dealer” 
The system may not be operating properly. Have the vehicle inspected by
any authorized Toyota retailer or Toyota authorized repairer, or any reliable
repairer.

●

“LTA Unavailable” 
The system is temporarily canceled due to a malfunction in a sensor other
than the front camera. Turn the LTA system off, wait for a little while, and
then turn the LTA system back on.

●

“LTA Unavailable at Current Speed” 
The function cannot be used as the vehicle speed exceeds the LTA opera-
tion range. Drive slower.

■

Customization

Function settings can be changed.
(Customizable features:



P. 153)

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RSA (Road Sign Assist)



The RSA system recognizes spe-
cific road signs using the front
camera and/or navigation system
(when speed limit information is
available) to provide information
to the driver via the display.

If the system judges that the vehicle is being driven over the speed
limit, performing prohibited actions, etc., according to the recognized
road signs, it notifies the driver through a visual notification and notifi-
cation buzzer.



: If equipped

Summary of function

WARNING

■

Before using the RSA

Do not rely solely upon the RSA system. RSA is a system which supports
the driver by providing information, but it is not a replacement for a driver’s
own vision and awareness. Drive safely by always paying careful attention
to the traffic rules.

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4-5. Using the driving support systems

When the front camera recognizes a sign and/or information of a sign
is available from the navigation system, the sign will be displayed on
the main display or multi-information display.

●

When the driving assist system
information is selected in multi-
information display, a maximum
of 2 signs can be displayed on
the multi-information display.
(



P. 127)

●

When a tab other than the driv-
ing assist system information is
selected, the following types of
road signs will be displayed on
the main display. (



P. 117)

• Speed limit begins/ends sign
• Speed limit related informa-

tion sign (Motorway,
Expressway, Urban area,
Residential area)

• End of prohibition sign
• No-entry sign

*

 (when notification is necessary)

• Speed limit with supplemental sign (Ramp way only)

*

: For vehicles with navigation system

If signs other than speed limit signs are recognized, they will be displayed
in an overlapping stack under the current speed limit sign.

Indication on the main display or multi-information display

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The following types of road signs, including electronic signs and blink-
ing signs, are displayed.

A non-official (not meeting the Vienna Convention) or a recently introduced
traffic sign may not be displayed.

●

Speed limit road signs

*

*

: No speed limit information 

 is displayed when speed limit sign or

speed limit related sign information is not available.

●

Speed limit related information

*

1, 2

*

1

: Displayed when a sign is recognized but speed limit information for the

road is not available from the navigation system

*

2

: No speed limit information 

 is displayed when speed limit sign or

speed limit related sign information is not available.

●

No-overtaking road signs

Supported types of road signs

Speed limit begins/
Maximum speed zone
begins

Speed limit ends/Maxi-
mum speed zone ends

Motorway entrance

Urban area ending

Motorway exit

Urban area beginning

Expressway entrance

Urban area ending

Expressway exit

Residential area begin-
ning

Urban area beginning

Residential area end-
ing

No overtaking begins

No overtaking ends