2011 Lexus HS250h brake sensor

189
2-3. Operating the lights and windshield wipers
2
When driving
Press the “ENTER” switch to
change to OFF.
The “AFS OFF” indicator will come
on.
Each pressing of the switch turns
AFS on and off.
Press the menu switch to change to
the normal display.
■Daytime running light system
●To make your vehicle more visible to othe r drivers, the headlights turn on auto-
matically (at a reduced intensity) whenever the hybrid system is started and the
parking brake is released. Daytime running lights are not designed for use at
night.
For the U.S.A.: Daytime running lights can be turned off by operating the switch.
●Compared to turning on th e headlights, the daytime running light system offers
greater durability and consumes less electricity, so it can help improve fuel
economy.
■Headlight control sensor
The sensor may not function properly if an
object is placed on the sensor, or anything
that blocks the sensor is affixed to the wind-
shield.
Doing so interferes with the sensor detecting
the level of ambient light and may cause the
automatic headlight system to malfunction.

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2-4. Using other driving systems
Driving in vehicle-to-vehicle distance control mode This mode employs a sensor to detect the presence of vehicles up to
approximately 400 ft. (120 m) ahead and to judge the distance between
your vehicle and those the vehicle ahead of you.
Note that vehicle-to-vehicle distance will close in when traveling on long
downhill slopes.
Example of constant speed cruising
When there are no vehicles ahead
The vehicle travels at the speed set by the driver. The desired vehicle-to-vehi-
cle distance can also be set by operat ing the vehicle-to-vehicle distance con-
trol.
Example of deceleration cruising
When the vehicle ahead is driving slower than the set speed
When a vehicle is detected running ahead of you, the system automatically
decelerates your vehicle. When a grea ter reduction in vehicle speed is nec-
essary, the system applies the brakes. A warning tone warns you when the
system cannot decelerate sufficiently to prevent your vehicle from closing in
on the vehicle ahead.

219
2-4. Using other driving systems
2
When driving
CAUTION
■Situations unsuitable for dynamic radar cruise control
Do not use dynamic radar cruise control in any of the following situations.
Doing so may result in inappropriate sp eed control and could cause an accident
resulting in death or serious injury.
●In heavy traffic
●On roads with sharp bends
●On winding roads
●On slippery roads, such as thos e covered with rain, ice and 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 expressways
●When weather conditions are bad enough that they may prevent the sensors
from functioning correctly (fog, sn ow, sandstorm, heavy rain, etc.)
●When an approach warning buzzer is heard often
■When the sensor may not be correctly detecting the vehicle ahead
Apply the brakes as necessary when any of the following types of vehicles are in
front of you.
As the sensor may not be able to correctly detect these types of vehicles, the
approach warning (P. 213) will not be activated, and a fatal or serious accident
may result.
●Vehicles that cut in suddenly
●Vehicles traveling at low speeds
●Vehicles that are not moving
●Vehicles with small rear ends (tra ilers with no load on board etc.)
●Motorcycles traveling in the same lane

220
2-4. Using other driving systems
CAUTION
■Conditions under which the vehicle-to-vehicle distance control may not function
correctly
Apply the brakes as necessary in the following conditions as the radar sensor may
not be able to correctly detect vehicles ahead, and a fatal or serious accident may
result:
●When water or snow thrown up by the surrounding vehicles hinders the function-
ing of the sensor
●When your vehicle is pointing upwards (c aused by a heavy load in the trunk etc.)
●When the road curves or when the lanes are narrow
●When steering wheel operation or your position in the lane is unstable
●When the vehicle ahead of you decelerates suddenly
■Handling the radar sensor
Observe the following to ensure the cruise control system can function effectively.
Otherwise, the system may not function correctly and could result in an accident.
●Keep the sensor and front grille cover clean at all times.
Clean the sensor and front grille cover with a soft cloth so you do not mark or
damage them.
●Do not subject the sensor or surrounding area to a strong impact.
If the sensor moves even slightly off position, the system may malfunction. If the
sensor or surrounding area is subject to a strong impact, always have the area
inspected and adjusted by a Lexus dealer.
●Do not disassemble the sensor.
●Do not attach accessories or stickers to the sensor, grille cover or surrounding
area.
●Do not modify or paint the sensor and grille cover.
●Do not replace them with non-genuine parts.

236
2-4. Using other driving systems
Pre-Collision System
: If equipped
When the radar sensor detects possibilit y of a frontal collision, the pre-col-
lision system such as the brakes and seat belts are automatically engaged
to lessen impact and injuries to occupants as well as vehicle damage.
■Pre-collision seat belts (front seat belts only)
If the pre-collision sensor detects that a collision is unavoidable, the pre-
collision system will retract the seat belt before the collision occurs.
The same will happen if the driver makes an emergency braking or loses
control of the vehicle. ( P. 7 5 )
However, when the VSC system is disabled, the system will not operate in
the event of skidding.
■ Pre-collision brake assist
When there is a high possibility of a frontal collision, the system applies
greater braking force in relation to how strongly the brake pedal is
depressed.
■Pre-collision braking
When there is a high possibility of a frontal collision, the system warns the
driver using a warning light, warning display* and buzzer. If the system
determines that a collision is unavoidable, the brakes are automatically
applied to reduce the collision speed. Pre-collision braking can be dis-
abled using the pre-collision braking off switch.
*: When the pre-collision braking system activates, “BRAKE!” will appear on the multi-information display and head-up display (if equipped), and
the warning light will begin flashing rapidly. ( P. 5 1 4 )
■Driver monitor system (if equipped)
When the system determines that there is a possibility of a frontal collision,
and the driver is not facing forward, PCS warnings are given in advance to
warn the driver. If the driver continue s to be not facing forward, and a high
possibility of a frontal collision is dete cted, PCS informs the driver of high
possibility of a frontal collision by perf orming slight braking to provide a
physically warning (pre-collision alert braking). ( P. 2 3 8 )

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2-4. Using other driving systems
Driver monitor sensor (if equipped)The driver monitor sensor detects
the direction the driver is facing.
The system determines whether
the driver is facing forward.
■The pre-collision seat belts are operational when
Pre-collision seat belts will activate in the following situations.
●Situation 1:
• Vehicle speed is greater than 19 mph (30 km/h).
• The system detects sudden braking or skidding.
• The front occupants are wearing a seat belt.
●Situation 2:
• Vehicle speed is greater than 4 mph (5 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming vehicle is greater than 19 mph (30 km/h).
• The front occupants are wearing a seat belt.
■The pre-collision systems (other than seat belts) are operational when
●Pre-collision brake assist:
• Vehicle speed is greater than 19 mph (30 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehicle running ahead of you is greater than 19 mph (30 km/h).
• The brake pedal is depressed.
●Pre-collision braking:
• The pre-collision braking off switch is not pressed.
• Vehicle speed is greater than 10 mph (15 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehicle
running ahead of you is greater than 10 mph (15 km/h).

239
2-4. Using other driving systems
2
When driving
●Pre-collision alert braking (vehicle with driver monitor system):
• The pre-collision braking off switch is not pressed.
• The system determines that the driver is not facing forward.
• Vehicle speed is greater than 10 mph (15 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehiclerunning ahead of you is grea ter than 25 mph (40 km/h).
■Conditions that may trigger the system even if there is no possibility of a collision
●When there is an object by the roadside at the entrance to a curve
●When passing an oncoming vehicle on a curve
●When driving over a narrow iron bridge
●When there is a metal object on the road surface
●When driving on an uneven road surface (nose up, nose down)
●When passing an oncoming vehicle on a left-turn
●When your vehicle rapidly closes on the vehicle in front
●When a grade separation/interchange, sign, billboard, or other structure
appears to be directly in the vehicle’s line of travel
●When climbing a steep hill causes an over head billboard or other metallic struc-
ture to appear directly in the vehicle’s line of travel
●When a railing, bar, or similar object can be seen in front of the vehicle
●When the radar sensor is out of alignment ( P. 2 4 3 )
When the system is activated in the situations described above, there is also a possi-
bility that the seat belts will retract quickly and the brakes will be applied with a force
greater than normal. When the seat belt is locked in the retracted position, stop the
vehicle in a safe place, release the seat belt and refasten it.
■Situations in which the pre-collision system does not function properly
The system may not function effectively in situations such as the following:
●On roads with sharp be nds or uneven surfaces
●On slippery roads such as th ose covered with ice or snow
●If a vehicle suddenly moves in front of your vehicle, such as at an intersection
●If a vehicle suddenly cuts in front of your vehicle, such as when overtaking
●In inclement weather such as heav y rain, fog, snow or sand storms
●When your vehicle is skidding with the VSC system off
●When the radar sensor is out of alignment ( P. 2 4 3 )

243
2-4. Using other driving systems
2
When driving
CAUTION
■When the sensor may not be correctly detecting the vehicle ahead
Apply the brakes as necessary in any of the following situations.
●When water or snow thrown up by the surrounding vehicles hinders the function-
ing of the sensor
●When your vehicle is pointing upwards (caused by a heavy load in the luggage
compartment etc.)
●Vehicles that cut in suddenly
●Vehicles with small rear ends (tra ilers with no load on board etc.)
●Motorcycles traveling in the same lane
■Handling the radar sensor
Observe the following to ensure the pre-collision system can function effectively:
●Keep the sensor and front grille cover clean at all times.
Clean the sensor and front grille cover with a soft cloth so you do not mark or
damage them.
●Do not subject the sensor or surrounding area to a strong impact.
If the sensor moves even slightly off po sition, the system may become inaccurate
or malfunction. If the sensor or surround ing area is subject to a strong impact,
always have the area inspected an d adjusted by your Lexus dealer.
●Do not disassemble the sensor.
●Do not attach accessories or stickers to the sensor, grille cover or surrounding
area.
●Do not modify or paint the sensor and grille cover.
■Determining the direction the driver is fa cing (vehicles with driver monitor sen-
sor)
The direction the driver is facing may not be determined correctly if the following
conditions exist:
●There is an object between the driver mo nitor sensor and the driver’s face, such
as when the sensor is blocked.
●A part of the driver’s face is covered.
●The sensor or the driver’s face is exposed to intense light such as sunlight.
●The driving posture is improper.