Toyota Prius Plug-in Hybrid (2023 year). Manual in english - page 24

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5-5. 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. 390)

●

If the operation conditions (



P. 391) 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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5-5. 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. 247)

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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.

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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5-5. 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. 220)

●

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. 212)

• 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.

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

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5-5. Using the driving support systems

●

No-overtaking road signs

●

Other road signs

*

: For vehicles with navigation system

●

Speed limit with supplemental mark

*

1

*

1

: Displayed simultaneously with speed limit.

*

2

: Contents not recognized.

*

3

: If the turn signal indicator is not operated when changing lanes, the mark

does not display.

No overtaking begins

No overtaking ends

No-entry

*

Stop

End of prohibition

Wet

Exit ramp on right

*

3

Rain

Exit ramp on left

*

3

Ice

Time

Supplemental mark
exists

*

2

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In the following situations, the RSA system will notify the driver.

●

When the vehicle speed exceeds the speed notification threshold of
the speed limit sign displayed, the sign display will be emphasized
and a buzzer will sound.

●

When the RSA system recognizes a no-entry sign and detects that
the vehicle has entered a no-entry area based on the map informa-
tion of the navigation system, the no-entry sign flashes and a
buzzer will sound. (For vehicles with navigation system)

●

If it is detected that your vehicle is overtaking when a no overtaking
sign is displayed on the multi-information display, the displayed sign
will flash and a buzzer will sound.

Depending on the situation, traffic environment (traffic direction,
speed unit) may be detected incorrectly and a notification function
may not operate properly.

■

Setting procedure



P. 247

■

Automatic turn-off of RSA sign display

One or more signs automatically turn off in the following situations.

●

No sign has been recognized for a certain distance.

●

The road changes due to a left or right turn, etc.

■

Conditions in which the function may not operate or detect correctly

In the following situations, RSA does not operate normally and may not rec-
ognize signs, display the incorrect sign, etc. However, this does not indicate a
malfunction.

●

The front camera is misaligned due to a strong impact being applied to the
sensor, etc.

●

Dirt, snow, stickers, etc. are on the windshield near the front camera.

●

In inclement weather such as heavy rain, fog, snow or sand storms

●

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

●

The sign is dirty, faded, tilted or bent.

●

The contrast of electronic sign is low.

●

All or part of the sign is hidden by the leaves of a tree, a pole, etc.

●

The sign is only visible to the front camera for a short amount of time.

●

The driving scene (turning, lane change, etc.) is judged incorrectly.

●

If a sign not appropriate for the currently traveled lane, but the sign exists
directly after a freeway branches, or in an adjacent lane just before merging.

Notification function

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5-5. Using the driving support systems

●

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 traveling on the main road.

●

Roundabout exit road speed signs may be detected and displayed (if posi-
tioned in sight of the front camera) while traveling on a roundabout.

●

The front of the vehicle is raised or lowered due to the carried load

●

The surrounding brightness is not sufficient or changes suddenly.

●

When a sign intended for trucks, etc. is recognized.

●

The vehicle is driven in a country with a different direction of traffic.

●

The navigation system map data is outdated.

●

The navigation system is not operating.

●

The speed information displayed on the meter and on the navigation 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 was displayed
on the main display or multi-information display, the same sign displays again
when the power switch is turned to ON mode.

■

If “RSA Malfunction Visit Your Dealer” is shown

The system may be malfunctioning. Have the vehicle inspected by any autho-
rized Toyota retailer or Toyota authorized repairer, or any reliable repairer.

■

Customization

Some functions can be customized. (Customizable features: 



P. 726)

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Dynamic radar cruise control



with full-speed 

range

In vehicle-to-vehicle distance control mode, the vehicle automatically
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 control with full-speed range on free-
ways and highways.

●

Vehicle-to-vehicle distance control mode (



P. 405)

●

Constant speed control mode (



P. 412)

Vehicle-to-vehicle distance
switch
Indicators
Multi-information display
Set speed
Cruise control switch

Summary of functions

System Components

1

2
3
4
5

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5-5. Using the driving support systems

WARNING

■

Before using dynamic radar cruise control with full-speed range

●

Driving safely is the sole responsibility of the driver. Do not rely solely on
the system, and drive safely by always paying careful attention to your sur-
roundings.

●

The dynamic radar cruise control with full-speed range provides driving
assistance to reduce the driver’s burden. However, there are limitations to
the assistance provided. 
Read the following conditions carefully. Do not overly rely on this system
and always drive carefully.
• When the sensor may not be correctly detecting the vehicle ahead:



P. 416

• Conditions under which the vehicle-to-vehicle distance control mode

may not function correctly:



P. 417

●

Set the speed appropriately depending on the speed limit, traffic flow, road
conditions, weather conditions, etc. The driver is responsible for checking
the set speed.

●

Even when the system is functioning normally, the condition of the preced-
ing vehicle as detected by the system may differ from the condition
observed by the driver. Therefore, the driver must always remain alert,
assess the danger of each situation and drive safely. Relying solely on this
system or assuming the system ensures safety while driving can lead to
an accident, resulting in death or serious injury.

●

Switch the dynamic radar cruise control with full-speed range setting to off
using the “ON-OFF” button when not in use.

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WARNING

■

Cautions regarding the driving assist systems

Observe the following precautions, as there are limitations to the assistance
provided by the system.
Failure to do so may cause an accident resulting in death or serious injury.

●

Assisting the driver to measure following distance
The dynamic radar cruise control with full-speed range is only intended to
help the driver in determining the following distance between the driver’s
own vehicle and a designated vehicle traveling ahead. It is not a mecha-
nism that allows careless or inattentive driving, and it is not a system that
can assist the driver in low-visibility conditions. It is still necessary for
driver to pay close attention to the vehicle’s surroundings.

●

Assisting the driver to judge proper following distance
The dynamic radar cruise control with full-speed range determines
whether the following distance between the driver’s own vehicle and a
designated vehicle traveling ahead is within a set range. It is not capable
of making any other type of judgement. Therefore, it is absolutely neces-
sary for the driver to remain vigilant and to determine whether or not there
is a possibility of danger in any given situation.

●

Assisting the driver to operate the vehicle
The dynamic radar cruise control with full-speed range does not include
functions which will prevent or avoid collisions with vehicles ahead of your
vehicle. Therefore, if there is ever any possibility of danger, the driver must
take immediate and direct control of the vehicle and act appropriately in
order to ensure the safety of all involved.

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WARNING

■

Situations unsuitable for dynamic radar cruise control with full-speed
range

Do not use dynamic radar cruise control with full-speed range in any of the
following situations.
Doing so may result in inappropriate speed control and could cause an acci-
dent resulting in death or serious injury.

●

Roads where there are pedestrians, cyclists, etc.

●

In heavy traffic

●

On roads with sharp bends

●

On winding roads

●

On slippery roads, such as those covered with rain, ice or snow

●

On steep downhills, or where there are sudden changes between sharp up
and down gradients 
Vehicle speed may exceed the set speed when driving down a steep hill.

●

At entrances to freeways and highways

●

When weather conditions are bad enough that they may prevent the sen-
sors from detecting correctly (fog, snow, sandstorm, heavy rain, etc.)

●

When there is rain, snow, etc. on the front surface of the radar or front
camera

●

In traffic conditions that require frequent repeated acceleration and decel-
eration

●

During emergency towing

●

When an approach warning buzzer is heard often

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This mode employs a radar to detect the presence of vehicles up to
approximately 100 m (328 ft.) ahead, determines the current vehicle-
to-vehicle following distance, and operates to maintain a suitable fol-
lowing distance from the vehicle ahead. The desired vehicle-to-vehi-
cle distance can also be set by operating the vehicle-to-vehicle
distance switch.

When driving on downhill slopes, the vehicle-to-vehicle distance may
become shorter.

Driving in vehicle-to-vehicle distance control mode

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Example of constant speed cruising
When there are no vehicles ahead

The vehicle travels at the speed set by the driver.

Example of deceleration cruising and follow-up cruising
When a preceding vehicle driving slower than the set speed
appears

When a vehicle is detected running ahead of you, the system automatically
decelerates your vehicle. When a greater reduction in vehicle speed is
necessary, the system applies the brakes (the stop lights will come on at
this time). The system will respond to changes in the speed of the vehicle
ahead in order to maintain the vehicle-to-vehicle distance set by the driver.
Approach warning warns you when the system cannot decelerate suffi-
ciently to prevent your vehicle from closing in on the vehicle ahead.
When the vehicle ahead of you stops, your vehicle will also stop (vehicle is
stopped by system control). After the vehicle ahead starts off, pushing the
cruise control lever up or depressing the accelerator pedal (start-off opera-
tion) will resume follow-up cruising. If the start-off operation is not per-
formed, system control continues to keep your vehicle stopped.
When the turn signal lever is operated and your vehicle moves to an over-
taking lane while driving at 80 km/h (50 mph) or more, the vehicle will
accelerate to help to overtake a passing vehicle.
The system’s identification of what is an overtaking lane may be deter-
mined solely based on the location of the steering wheel in the vehicle (left
side driver position versus right side driver position.) If the vehicle is driven
to a region where the overtaking lane is on a different side from where the
vehicle is normally driven, the vehicle may accelerate when the turn signal
lever is operated in the opposite direction to the overtaking lane (e.g., if the
driver normally operates the vehicle in a region where the overtaking lane
is to the right but then drives to a region where the overtaking lane is to the
left, the vehicle may accelerate when the right turn signal is activated).

Example of acceleration 
When there are no longer any preceding vehicles driving slower
than the set speed

The system accelerates until the set speed is reached. The system then
returns to constant speed cruising.

1

2

3

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Press the “ON-OFF” button to
activate the cruise control.

Dynamic radar cruise control indi-
cator will come on and a message
will be displayed on the multi-infor-
mation display.
Press the button again to deacti-
vate the cruise control.
If the “ON-OFF” button is pressed
and held for 1.5 seconds or more,
the system turns on in constant
speed control mode. (



P. 412)

Accelerate or decelerate, with
accelerator pedal operation, to
the desired vehicle speed (at or
above approximately 30 km/h
[20 mph]) and push the lever
down to set the speed.

Cruise control “SET” indicator will
come on.
The vehicle speed at the moment
the lever is released becomes the
set speed.

Setting the vehicle speed (vehicle-to-vehicle distance control
mode)

1

2