2010 Lexus HS250h brake sensor

186
2-3. Operating the lights and windshield wipers
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 norma
l display.
■Daytime running light system (if equipped)
To make your vehicle more visible to othe r dr
ivers, the headlights turn on automati-
cally (at a reduced intensity) whenever the hy
brid system is started and the parking
brake is released. Daytime running ligh ts are not designed for use at night.
For the U.S.A.: Daytime running lights can be turned off by operating the switch.
■Headlight control sensor
■Automatic light off system
●When the headlights come on: The headligh ts and tail lights turn off 30 seconds
after a door is opened and closed if the “POWER” switch is turned to ACCES -
SORY mode or turned off. (The lights turn off immediately if on the key is
pressed after all the doors are locked.)
●When only the tail lights come on: The tail lights turn off automatically if the
“POWER” switch is turned to ACCESSORY mode or turned off and the
driver’s door is opened.
To turn the lights on again, turn the “POWER” s
witch to ON mode, or turn the light
switch off once and then back to or .
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.

209
2-4. Using other driving systems
2
When driving
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 operating 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
s
ystem cannot decelerate sufficiently to prevent your vehicle from closing in
on the vehicle ahead.

215
2-4. Using other driving systems
2
When driving
CAUTION
●Assisting the driver to judge proper following distance 
The dynamic radar cruise control determ ines whether the following distance
between the driver’s own vehicle and a designated vehicle travelling ahead is
appropriate or not. It is not capable of making any other type of judgement.
Therefore, it is absolutely necessary for the driver to remain vigilant and to deter-
mine whether or not there is a possibil ity of danger in any given situation.
●Assisting the driver to operate the vehicle 
The dynamic radar cruise control has no capability to prevent or avoid a collision
with a vehicle travelling ahead. Therefore, if there is ever any danger, the driver
must take immediate and direct control of the vehicle and act appropriately in
order to ensure the safety of all involved.
■To avoid inadvertent cruise control activation
Switch the cruise control off using the “ON-OFF” button when not in use.
■Situations unsuitable for dynamic radar cruise control
Do not use dynamic radar cruise contro l 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 vehi-
cles, the approach warning (P. 210) will not be activated, and a fatal or serious
accident may result.

216
2-4. Using other driving systems
CAUTION
●Vehicles that cut in suddenly
●Vehicles traveling at low speeds
●Vehicles that are not moving
●Vehicles with small rear ends (trailers with no load on board etc.)
●Motorcycles traveling in the same lane
■Conditions under which the vehicle-to-vehicle distance control may not function
correctly
Apply the brakes as necessary in the foll owing 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.

232
2-4. Using other driving systems
Pre-Collision System
: If equipped
When the radar sensor detects an unavoidable frontal collision, safety sys-
tems 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 roll up the seat belt before the collision occurs. 
The same will happen if the driver makes an emergency braking or loses
contr
ol of the vehicle. ( P. 74 )
However, when the TRAC/VSC systems are disabled, the system will not
oper
ate 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 button.
■ Driver monitor system (if equipped)
When the system determines that ther e is a possibility of a collision, and
the driver is not facing forward, PC S warnings are given in advance to
warn the driver. If the driver contin ues to be not facing forward, and a
probable collision is detected, PCS in forms the driver of danger by per-
forming slight braking to provide a physically warning (pre-collision alert
br
aking). ( P. 2 3 5)

234
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 system is operational when
●Pre-collision warning
• Vehicle speed is greater than about 9 mph (15 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming v
ehicle is greater than about 9 mph (15 km/h).
●Pre-collision seat belts (linked to brake operation)
• Vehicle speed is greater than about 18 mph (30 km/h).
• The system detects sudd en
braking or skidding.
• The front occupants are wearing a seat belt.
●Pre-collision seat belts (linked to the radar sensor)
• Vehicle speed is greater than about 3 mph (5 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming v
ehicle is greater than about 18 mph (30 km/h).
• The front occupants are wearing a seat belt.
●Pre-collision brake assist:
• Vehicle speed is greater than about 18 mph (30 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehicle running
ahead of you is greate r than about 18 mph (30 km/h).
• The brake pedal is depressed.

235
2-4. Using other driving systems
2
When driving
●Pre-collision braking:
• The pre-collision braking off button is not pressed.
• Vehicle speed is greater than about 9 mph (15 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehicle running ahead of you is greater than about 9 mph (15 km/h).
●Pre-collision alert braking (vehicle with driver monitor system):
• The pre-collision braking off button is not pressed.
• The system determines that the driver is not facing forward.
• Vehicle speed is greater than about 9 mph (15 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehicle running ahead of you is greate r than about 24 mph (40 km/h).
■Conditions that may trigger the system even if there is no danger 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
●When passing an oncoming vehicle on a left-turn
●When your vehicle rapidly closes on the vehicle in front
When the system is activated in the situations described above, there is also a possi-
bility that the seat belts will roll up 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.
■Obstacles not detected
The sensor cannot detect plastic obstacles such as traffic cones. There may also be
occasions when the sensor cannot detect pedestrians, animals, bicycles, motorcy-
cles, trees, or snowdrifts.
■When there is a malfunction in the system
Warning lights and/or warning messages will turn on or flash. ( P. 493, 502, 505)

237
2-4. Using other driving systems
2
When driving
CAUTION
■Limitations of the pre-collision system
Do not overly rely on the pre-collision system. Always drive safely, taking care to
observe your surroundings and checking for any obstacles or other road hazards.
■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 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 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.