2011 Lexus HS250h brake

238
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).

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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 )

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2-4. Using other driving systems
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.
Failure to do so may cause an accident resulting in death or serious injury.
■Cautions regarding the assist contents of the system
By means of alarms and brake control, the pre-collision system is intended to assist
the driver in avoiding collisions through the process of LOOK-JUDGE-ACT. There
are limits to the degree of assistance the system can provide, so please keep in mind
the following important points.
●Assisting the driver in watching the road
The pre-collision system is only able to detect obstacles directly in front of the
vehicle, and only within a limited range. It is not a mechanism that allows careless
or inattentive driving, and it is not a system that can assist the driver in low-visibil-
ity conditions. It is still necessary for the driver to pay close attention to the vehi-
cle’s surroundings.
●Assisting the driver in making correct judgment
When attempting to estimate the possibil ity of a frontal collision, the only data
available to the pre-collision system is that from obstacles it has detected directly
in front of the vehicle. Therefore, it is absolutely necessary for the driver to remain
vigilant and to determine whether or not th ere is a possibility of collision in any
given situation.
●Assisting the driver in taking action
The pre-collision system’s braking assist feature is designed to help reduce the
severity of a collision, and so only acts when the system has judged that a collision
is unavoidable. This system by itself is not capable of automatically avoiding a col-
lision or bringing the vehicl e to a stop safely. For this reason, when encountering a
dangerous situation the driver must take direct and immediate action in order to
ensure the safety of all involved.

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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.

247
2-5. Driving information
2
When driving
CAUTION
■Things that must not be carried in the trunk
The following things may cause a fire if loaded in the trunk:
●Receptacles containing gasoline
●Aerosol cans
■Storage precautions
Observe the following precautions.
Failing to do so may result in death or serious injury.
●Stow cargo and luggage in the trunk whenever possible.
●Do not place cargo or luggage in or on the following locations as the item may
get under the brake or accelerator pedal and prevent the pedals from being
depressed properly, block the driver’s vision, or hit the driver or passengers,
causing an accident:
• At the feet of the driver
• On the front passenger or rear seats (when stacking items)
• On the package tray
• On the instrument panel
•On the dashboard
●Secure all items in the occupant compartment, as they may shift and injure some-
one during sudden braking, sudd en swerving or an accident.
■Capacity and distribution
●Do not exceed the maximum axle weight ra ting or the total vehicle weight rating.
●Even if the total load of occupant’s weight and the cargo load is less than the total
load capacity, do not apply the load unevenly. Improper loading may cause dete-
rioration of steering or braking control which may cause death or serious injury.

249
2-5. Driving information
2
When driving
Winter driving tips
Carry out the necessary preparations and inspections before driving the
vehicle in winter. Always drive the vehicle in a manner appropriate to the
prevailing weather conditions.
■ Pre-winter preparations
●Use fluids that are appropria te to the prevailing outside tempera-
tures.
• Engine oil
• Engine/power control unit coolant
• Washer fluid
● Have the vehicle fitted with four snow tires or purchase a set of
tire chains for the front tires.
Ensure that all tires are the same size and brand, and that chains match
the size of the tires.
■ Before driving the vehicle
Perform the following accord ing to the driving conditions:
● Do not try to forcibly open a w indow or move a wiper that is fro-
zen. Pour warm water over the frozen area to melt the ice. Wipe
away the water immediately to prevent it from freezing.
● To ensure proper operation of the climate control system fan,
remove any snow that has accumu lated on the air inlet vents in
front of the windshield.
● Remove any ice that has accumul ated on the vehicle chassis.
● Periodically check for and remove any excess ice or snow that
may have accumulated in the wheel well or on the brakes.
■ When driving the vehicle
Accelerate the vehicle slowly and drive at a reduced speed suitable to the
road conditions.

250
2-5. Driving information
Selecting tire chainsUse the correct tire chain size when mounting the tire chains. Chain size
is regulated for each tire size.
Side chain:0.12 in. (3 mm) in diameter
Cross chain: 0.16 in. (4 mm) in diameter
Regulations on the use of tire chains
Regulations regarding the use of tire chains vary depending on location
and type of road. Always check local regulations before installing chains.
■When parking the vehicle
Park the vehicle and push the P po sition switch without setting the
parking brake. The parking brake may freeze up, preventing it from
being released. If necessary, bl ock the wheels to prevent inadvert-
ent sliding or creeping.
■Tire chain installation
Observe the following precautions when installing and removing chains:
●Install and remove tire chains in a safe location.
●Install tire chains on the front tires only. Do not install tire chains on the rear tires.
●Install tire chains on front tires as tightl y as possible. Retighten chains after driv-
ing 1 /4  1/2 mile (0.5  1.0 km).
●Install tire chains following the instructions provided with the tire chains.

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4-2. Maintenance
4
Maintenance and care
General maintenance
Engine compartment
Tr u n k
ItemsCheck points
Brake fluidIs the brake fluid at the correct level?(P. 4 3 7 )
CoolantIs the engine coolant at the correct
level? ( P. 4 3 4 )
Engine oilIs the engine oil at the correct level?
(P. 4 3 0 )
Exhaust systemThere should not be any fumes or
strange sounds.
Radiator/condenser
The radiator and condenser should
be free from foreign objects.
(P. 4 3 6 )
Wa s h e r f l u i dIs there sufficient washer fluid?
( P. 4 3 8 )
ItemsCheck points
12-volt batteryCheck the connections. ( P. 4 3 9 )
Listed below are the general maintenance items that should be performed
at the intervals specified in the “Warranty and Service Guide” or “Owner’s
Manual Supplement”. It is recomme nded that any problem you notice
should be brought to the attention of your Lexus dealer or qualified service
shop for advice.