2018 Lexus GS450h lane assist

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LKA (Lane-Keeping Assist)∗
When driving on highways and freeways with white or yellow lines, this function
alerts the driver when the vehicle might depart from its lane and provides assis-
tance by operating the steering wheel to keep the vehicle in its lane. Further-
more, the system also provides steering assistance when dynamic radar cruise
control with full-speed range is operat ing to keep the vehicle in its lane.
The LKA system recognizes visible
white or yellow lines with the camera
sensor on the upper portion of the front
windshield.
◆Lane departure alert function
When the system determines that
the vehicle might depart from its
lane, a warning is displayed on the
multi-information display, and either
the warning buzzer sounds
or the
steering wheel vibrates to alert the
driver.
When the warning buzzer sounds or
the steering wheel vibrates, check
the surrounding road situation and
carefully operate the steering wheel
to move the vehicle back to the cen-
ter of the lane.
∗: If equipped
Summary of functions
Functions included in LKA system

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Driving
◆Steering assist function
When the system determines that
the vehicle might depart from its
lane, the system provides assistance
as necessary by operating the steer-
ing 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-
information display and the warning
buzzer sounds.
◆Vehicle sway warning function
When the vehicle is swaying or
appears as if it may depart from its
lane multiple times, the warning
buzzer sounds and a message is dis-
played on the multi-information dis-
play to alert the driver.

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◆Lane centering function
This function is linked with radar
cruise control and provides the
required assistance by operating the
steering wheel to keep the vehicle in
its current lane.
When radar cruise control is not
operating, the lane centering func-
tion does not operate.
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 warning
buzzer sounds.
WARNING
■Before using LKA system
Do not rely solely upon the LKA system. The LKA system does not automatically 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 surrounding cond itions 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 operat ions and pay careful attention may lead to
an accident, resulting in death or serious injury.

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Press the LKA switch to turn the LKA
system on.
The LKA indicator illuminates and a
message is displayed on the multi-infor-
mation display.
Press the LKA switch again to turn the
LKA system off.
When the LKA system is turned on or
off, operation of the LKA system contin-
ues in the same condition the next time
the hybrid system is started.
LKA indicator
The illumination condition of the
indicator informs the driver of the
system operation status.
Illuminated in white:
LKA system is operating.
Illuminated in green:
Steering wheel assistance of the steer-
ing assist function or lane centering
function is operating.
Flashing in orange:
Lane departure alert function is operat-
ing.
Operation display of steering wheel
operation support
Indicates that steering wheel assistance of the steering assist function or lane
centering function is operating.
Turning LKA system on
Indications on multi-information display
1
2

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Lane departure alert function display
Displayed when the multi-information display is switched to the driving assist
system information screen.
■Operation conditions of each function
●Lane departure alert function
This function operates when all of the following conditions are met.
• LKA is turned on.
• Vehicle speed is approximatel y 32 mph (50 km/h) or more.
• System recognizes white (yellow) lines.
• Width of traffic lane is approx imately 9.8 ft. (3 m) or more.
• Turn signal lever is not operated.
• Vehicle is driven on a straight road or around a gentle curve with a radius of more
than approximately 492 ft. (150 m).
• No system malfunctions are detected. ( →P. 242)
●Steering assist function
This function operates when all of the follo wing conditions are met in addition to the
operation conditions for the lane departure alert function.
• Setting for “Steering Assist” in of the multi-information display is set to “On”.
( → P. 95)
• Vehicle is not accelerated or dece lerated 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 (Pre-Collision System) are not operating.
• TRAC or VSC is not turned off.
3
Inside of displayed white lines is
whiteInside of displayed white lines is
black
Indicates that the system is recognizing
white (yellow) lines. When the vehicle
departs from its lane, the white line dis-
played on the side the vehicle departs
from flashes orange. Indicates that the system is not able to
recognize white (ye
llow) lines or is
temporarily canceled.

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●Vehicle sway warning function
This function operates when all of the following conditions are met.
• Setting for “Sway Warning” in of the multi-information display is set to “On”.
( → P. 95)
• Vehicle speed is approximatel y 32 mph (50 km/h) or more.
• Width of traffic lane is approx imately 9.8 ft. (3 m) or more.
• No system malfunctions are detected. ( →P. 242)
●Lane centering function
This function operates when all of the following conditions are met.
• LKA is turned on.
• Setting for “Steering Assist” and “Lane Center” in of the multi-information
display are set to “On”. ( →P. 95)
• System recognizes white (yellow) lines.
• Dynamic radar cruise control with full-speed range is operating.
• Width of traffic lane is approximately 8.2 to 13.5 ft. (2.5 to 4.1 m).
• Turn signal lever is not operated.
• Vehicle is driven on a straight road or around a gentle curve with a radius of more
than approximately 656 ft. (200 m).
• No system malfunctions are detected. ( →P. 242)
• Vehicle does not accele rate or decelerate 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 (Pre-Collision System) are not operating.
• TRAC or VSC is not turned off.
• Steering assist function is not operating.
■Temporary cancellation of functions
When operation conditions are no longer met, a function may be temporarily canceled.
However, when the operation conditions are met again, operat ion of the function is auto-
matically restored. ( →P. 239)
■Steering assist function/lane centering function
Depending on the vehicle speed, lane depart ure situation, road conditions, etc., the
driver may not feel the function is operating or the function may not operate at all.
■Lane departure alert function
The warning buzzer may be difficult to hear due to external noise, audio playback, etc.
Also, it may be difficult to f eel steering wheel vibrations due to the road conditions, etc.

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■Hands off steering wheel alert
When the system determines that the driver has removed the hands from the steering
wheel while the steering assist function or lane centering function is operating, a warning
message is displayed on th e multi-information display.
If the driver continues to keep the hands off of the steering wheel, a buzzer sounds, a
warning message is displayed. This alert also operates in the same way when the driver
continuously operates the steering wheel only a small amount. However, depending on
the road conditions, etc., the function may not cancel.
■White (yellow) lines are only on one side of road
The LKA system will not operate for the side on which white (yellow) lines could not be
recognized.
■Conditions in which functions may not operate properly
In the following situations, the camera sensor may not detect white (yellow) lines and var-
ious functions may not operate normally.
●There are shadows on the road that run parallel with, or cover, the white (yellow) lines.
●The vehicle is driven in an ar ea 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.
●The vehicle is driven on a surface that is bright due to reflected light, etc.
●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 where the road diverges, merges, etc.
●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 vehicle is driven around a sharp curve.
●The traffic lane is excessively narrow or wide.
●The vehicle is extremely tilted due to carry ing 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 am ount due to road conditions during driv-
ing (poor roads or road seams).

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●The headlight lenses are dirty and emit a faint amount of light at night, or the beam axis
has deviated.
●The vehicle is struck by a crosswind.
●The vehicle has just changed lanes or crossed an intersection.
●Snow tires, etc. are equipped.
■Warning message
Warning messages are used to indicate a syst em malfunction or to inform the driver of
the need for caution while driving. ( →P. 410)
■Customization
The following settings can be changed.
For how to change settings, refer to P. 494
FunctionSetting details
Lane departure alert functionAdjust alert sensitivity
Adjust alert type
Steering assist functionTurn steering wheel assistance on and off
Vehicle sway warning functionTurn function on and off
Adjust alert sensitivity
Lane centering functionTurn function on and off