2010 Lexus HS250h sensor

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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 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.

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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.

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2-4. Using other driving systems
CAUTION
■Determining the direction the driver is facing (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 monitor 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.
■Handling the driver monitor sensor (vehicles with driver monitor sensor)
Observe the following to ensure the driver monitor sensor can function effectively. 
Failure to do so may result in a malfunction or may prevent the system from cor-
rectly determining the direction the driver is facing, resulting in an unexpected acci-
dent.
●Do not disassemble, damage, lift or pull on the sensor.
●Do not touch the sensor while driving.
●Do not wet or spill water on the sensor.
●Do not drop anything on or allow anything to hit against the sensor. Do not sub-
ject the sensor to an impact.
●Make sure that there are no scratches, dirt or stickers on the side of the sensor
that faces the driver.
●Do not place any objects in front of the side of the sensor that faces the driver or
cover the sensor.

239
2-4. Using other driving systems
2
When driving
NOTICE
■Precautions for cleaning the driver monitor sensor (vehicles with driver monitor
sensor)
●Gently wipe the sensor with a soft cloth to prevent damage.
●Wipe any excess dirt with a cloth dampened with neutral detergent, all liquids
having been wrung out of the cloth. After that, wipe again with a dry cloth.
●Do not use benzene, thinner, glass cleaners, wax, etc.

394
3-7. Other interior features
■Conditions unfavorable to correct operation
The compass may not show the correct direction in the following conditions:
●The vehicle is stopped immediately after turning.
●The vehicle is on an inclined surface.
●The vehicle is in a place where the earth’s magnetic field is subject to interfer-
ence by artificial magnetic fields (underground car park/parking lot, under a
steel tower, between buildings, roof car park/parking lot, near an intersection,
near a large vehicle, etc.).
●The vehicle has become magnetized. (There is a magnet or metal object near
the inside rear view mirror.)
●The battery has been disconnected.
●A door is open.
CAUTION
■While driving the vehicle
Do not adjust the display. Adjust the di splay only when the vehicle is stopped.
■When doing the circling calibration
Secure a wide space, and watch out for people and vehicles in the vicinity. Do not
violate any local traffic rules while performing circling calibration.
NOTICE
■To avoid compass malfunctions
Do not place magnets or any metal objects near the inside rear view mirror.
Doing this may cause the compass sensor to malfunction.
■To ensure normal operation of the compass
●Do not perform a circling calibration of the compass in a place where the earth’s
magnetic field is subject to interference by artificial magnetic fields.
●During calibration, do not operate elec tric systems (moon roof, power windows,
etc.) as they may interfere with the calibration.

490
5-1. Essential information
Event data recorder
In a crash or a near crash event
The SRS airbag sensor assembly contains the EDR. In a crash or near
crash event, this device may record some or all of the following informa-
tion:
● Engine speed
● Whether the br
ake pedal was applied or not
● V
ehicle speed
●T
o what extent the accelerator pedal was depressed
●Hybrid tr
ansmission shift position
●Whether the driv
er and front passenger wore seat belts or not
● D
river's seat position
●SRS airbag deplo
yment data
● SRS airbag s
ystem diagnostic data
● F
ront passenger’s occupant classification
The information abov e is intended to be used for the purpose of impr
ov-
ing vehicle safety performance. Unlike general da ta recorders, the EDR
does not record sound data such as conversation between passengers.
Your vehicle has computers that monitor and control certain aspects of
your vehicle. These computers assist in driving and maintaining optimal
vehicle performance.
Besides storing data usef ul for troubleshooting, there is an event data
recorder (EDR) that records data in a crash or near crash event.

496
5-2. Steps to take in an emergency
*1: Open door warning buzzer:
P. 5 0 5
*2: Driver’s and front passenger’s seat belt buzzer:
The driver’s and front passenger’s seat belt buzzer sounds to alert the driver and
front passenger that his or her seat belt is not fastened. The buzzer sounds inter-
mittently for 10 seconds after the vehicle
reaches a speed of 12 mph (20 km/h).
Then, if the seat belt is still unfastened, the buzzer will sound in a different tone
for 20 more seconds.
Tire pressure warning light
When the light comes on: 
Low tire inflation pressureAdjust the tire inflation pres-
sure.
When the light comes on after
blinking for 1 minute: 
Malfunction in the tire pres-
sure warning system
Have the system checked by
your Lexus dealer.
■SRS warning light
This warning light system monitors the airb ag
sensor assembly, front airbag sensors,
side and curtain shield airbag sensors, curtain shield and rear side airbag sensors,
driver’s seat position sensor , driver’s seat belt buckle switch, front passenger occu -
pant classification system, “AIR BAG ON” indicator light, “
AIR BAG OFF” indicator
light, front passenger’s seat belt buckle switch, seat belt pretensioner assemblies,
inflators, interconnecting wiring and power sources. ( P. 1 0 5)
■Front passenger detection sensor, passenger seat belt reminder and warning
buzzer
●If luggage is placed on the front passenger seat, the front passenger detection
sensor may cause the warning light to flash and the warning buzzer to sound
even if a passenger is not sitting in the seat.
●If a cushion is placed on the seat, the sensor may not detect a passenger, and the
warning light may not operate properly.
Warning lightWarning light/DetailsCorrection procedure