2021 TOYOTA PRIUS Owners Manual (in English)

PRIUS_OM_OM47E09U_(U)
2974-5. Using the driving support systems
4
Driving
■Pre-collision warning
When the system determines
that the possibility of a frontal
collision is high, a buzzer will
sound and a warning message
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 colli-
sion is high, the system applies greater braking force in relat ion to
how strongly the brake pedal is depressed.
■Pre-collision braking
If the system determines that the possibility of a frontal collision is
extremely high, the brakes are automatically applied to help avoid
the collision or reduce th e impact of the collision.
System functions

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PRIUS_OM_OM47E09U_(U)
4-5. Using the driving support systems
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 o perations
under any circumstances. This system will not prevent collision s or lessen
collision damage or injury in every situation. Do not overly re ly on this sys-
tem. Failure to do so may lead to an accident, resulting in dea th or serious
injury.
● Although this system is designed to help avoid a collision or h elp reduce
the impact of the collision, its effectiveness may change according to vari-
ous conditions, therefore the system may not always be able to achieve
the same level of performance.
Read the following conditions carefully. Do not overly rely on this system
and always drive carefully.
• Conditions under which the system may operate even if there is no pos-
sibility of a collision: P. 302
• Conditions under which the system may not operate properly: P. 304
● Do not attempt to test the operation of the pre-collision syste m yourself.
Depending on the objects used for testing (dummies, cardboard o bjects
imitating detectable objects, etc.), the system may not operate properly,
possibly leading to an accident.
■ Pre-collision braking
● When the pre-collision braking function is operating, a large a mount of
braking force will be applied.
● If the vehicle is stopped by the operation of the pre-collision braking func-
tion, the pre-collision braking function operation will be canceled after
approximately 2 seconds. Depress the brake pedal as necessary.
● The pre-collision braking function may not operate if certain o perations are
performed by the driver. If the accelerator pedal is being depressed
strongly or the steering wheel is being turned, the system may determine
that the driver is taking evasive action and possibly prevent t he pre-colli-
sion braking function from operating.
● In some situations, while the pre-collision braking function is operating,
operation of the function may be canceled if the accelerator pedal is
depressed strongly or the steering wheel is turned and the syst em deter-
mines that the driver is taking evasive action.
● If the brake pedal is being depressed, the system may determine that the
driver is taking evasive action and possibly delay the operation timing of
the pre-collision braking function.

PRIUS_OM_OM47E09U_(U)
2994-5. Using the driving support systems
4
Driving
WARNING
■When to disable the pre-collision system
In the following situations, disable the system, as it may not operate prop-
erly, possibly leading to an accident resulting in death or ser ious injury:
● When the vehicle is being towed
● When your vehicle is towing another vehicle
● When transporting the vehicle via truck, boat, train or similar means of
transportation
● When the vehicle is raised on a lift with the hybrid system on and the tires
are allowed to rotate freely
● When inspecting the vehicle using a drum tester such as a chass is dyna-
mometer or speedometer tester, or when using an on vehicle whee l bal-
ancer
● When a strong impact is applied to the front bumper or front gr ille, due to
an accident or other reasons
● If the vehicle cannot be driven in a stable manner, such as when the vehi-
cle has been in an accident or is malfunctioning
● When the vehicle is driven in a sporty manner or off-road
● When the tires are not properly inflated
● When the tires are very worn
● When tires of a size other than specified 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 sens or or front
camera is temporarily installed to the vehicle

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PRIUS_OM_OM47E09U_(U)
4-5. Using the driving support systems
■Enabling/disabling th e pre-collision system
The pre-collision system can be enabled/disabled on ( P. 151)
of the multi-information display.
The system is automatically enabled each time the power switch is
turned to ON mode.
If the system is disabled, the
PCS warning light will turn on
and a message will be dis-
played on the multi-information
display.
■Changing the pre-colli sion warning timing
The pre-collision warning ti ming can be changed on ( P. 151)
of the multi-information display.
The warning timing setting is retained when the power switch is turned
off.
However, if the pre-collision system is disabled and re-enabled , the
operation timing will return to the default setting (middle).
Early
Middle
This is the default setting.
Late
Changing settings of the pre-collision system
1
2
3

PRIUS_OM_OM47E09U_(U)
3014-5. Using the driving support systems
4
Driving
■Operational conditions
The pre-collision system is enabled and the system determines that the pos-
sibility of a frontal collision with a detected object is high.
Each function is operational at the following speed
●Pre-collision warning
● Pre-collision brake assist
● Pre-collision braking
The system may not operate in the following situations:
● If a 12-volt battery terminal has been disconnected and reconnected and
then the vehicle has not been driven for a certain amount of ti me
● If the shift position is in R
● When the VSC OFF indicator is illuminated (only the pre-collisi on warning
function will be operational)
Detectable objectsVehicle speedRelative speed between your vehicle and object
VehiclesApprox. 7 to 110 mph
(10 to 180 km/h)Approx. 7 to 110 mph
(10 to 180 km/h)
Bicyclists and pedestri-
ansApprox. 7 to 50 mph
(10 to 80 km/h)Approx. 7 to 50 mph
(10 to 80 km/h)
Detectable objectsVehicle speedRelative speed between your vehicle and object
VehiclesApprox. 20 to 110 mph
(30 to 180 km/h)Approx. 20 to 110 mph
(30 to 180 km/h)
Bicyclists and pedestri-
ansApprox. 20 to 50 mph
(30 to 80 km/h)Approx. 20 to 50 mph
(30 to 80 km/h)
Detectable objectsVehicle speedRelative speed between your vehicle and object
VehiclesApprox. 7 to 110 mph
(10 to 180 km/h)Approx. 7 to 110 mph
(10 to 180 km/h)
Bicyclists and pedestri-
ansApprox. 7 to 50 mph
(10 to 80 km/h)Approx. 7 to 50 mph
(10 to 80 km/h)

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PRIUS_OM_OM47E09U_(U)
4-5. Using the driving support systems
■Object detection function
■ Cancelation of the pre-collision braking
If either of the following occur while the pre-collision brakin g 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 determ ine 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 o bjects,
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. 304)
The illustration shows an image of detect-
able objects.
• When approaching a detectableobject in an adjacent lane or on the
roadside, such as when changing the
course of travel or driving on a wind-
ing road

PRIUS_OM_OM47E09U_(U)
3034-5. Using the driving support systems
4
Driving
• 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, et c.
• 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 whe n 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 b arrier, 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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PRIUS_OM_OM47E09U_(U)
4-5. Using the driving support systems
• 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 syst em 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 sudde n 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 o r 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, et c.
• When a very bright light ahead, such as the sun or the headlig hts 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