2009 Lexus IS250 brakes

178
2-4. Using other driving systems
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 co ntrol of speed and could cause serious or
fatal accident.
●In heavy traffic
●On roads with sharp bends
●On winding roads
●On slippery roads, such as thos e covered with rain, ice or snow
●On steep downhills, or where there are sudden changes between sharp up and
down gradients
●At entrances to expressways
●When weather conditions are bad enough that they may prevent the sensors
from functioning correctly (f og, snow, sandstorm, etc.)
●Where buzzer can be heard often
■When the radar 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 prox-
imity alarm ( P. 392) will not be activated, and an 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

179
2-4. Using other driving systems
2
When driving
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 an 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 (caused 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:
●Keep the sensor and front grille clean at all times.
Clean the sensor and front grille with a so ft 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 or surrounding area.
●Do not modify or paint the sensor and grille.
■To ensure the radar sensor functions correctly
Do not do the following to the sensor or grille cover as doing so may cause the sen-
sor not to function correctly and could result in an accident.
●Stick or attach anything to them
●Leave them dirty
●Disassemble, subject them to strong shocks
●Modify or paint them
●Replace them with non-genuine parts

184
2-4. Using other driving systems
■Sensor detection information
●Certain vehicle conditions and the surrounding environment may affect the
ability of the sensor to correctly detect obstacles. Particular instances where this
may occur are listed below.
• There is dirt, snow or ice on the sensor.
• The sensor is frozen.
• The sensor is covered in any way.
• The vehicle is leaning considerably to one side.
• On an extremely bumpy road, on an incline, on gravel, or on grass.
• The vicinity of the vehicle is noisy due to vehicle horns, motorcycle engines,
air brakes of large vehicles, or other loud noises producing ultrasonic waves.
• There is another vehicle equipped with parking assist sensors in the vicinity.
• The sensor is coated with a sheet of spray or heavy rain.
• The vehicle is equipped with a fender pole or wireless antenna.
• Towing eyelets are installed.
• The bumper or sensor receives a strong impact.
• The vehicle is approaching a tall or curved curb.
• In harsh sunlight or intense cold weather
In addition to the examples above, there are instances in which, because of their
shapes, signs and other object s may be judged by the sensor to be closer than they
are.
●The shape of the obstacle may prevent th e sensor from detecting it. Pay particu-
lar attention to the following obstacles.
• Wires, fences, ropes etc.
• Cotton, snow and other materials that absorb radio waves
• Sharply-angled objects
•Low obstacles
• Tall obstacles with upper sections projec ting outwards in the direction of your
vehicle
■When the display flashes an d a message is displayed
 P. 3 9 2

186
2-4. Using other driving systems
Driving assist systems
To help enhance driving safety and performance, the following systems
operate automatically in response to various driving situations. Be aware,
however, that these systems are supplementary and should not be relied
upon too heavily when operating the vehicle.
■ABS (Anti-lock Brake System)
Helps to prevent wheel lock when the brakes are applied suddenly, or if
the brakes are applied while driving on a slippery road surface.
■Brake assist
Generates an increased level of braking force after the brake pedal is
depressed, when the system detects a panic stop situation.
■VSC (Vehicle Stability Control)
Helps the driver to control skidding when swerving suddenly or turning on
slippery road surfaces.
■ TRAC (Traction Control)
Maintains drive power and prevents th e rear wheels (2WD models) or all
wheels (AWD models) from spinning when starting the vehicle or acceler-
ating on slippery roads.
■ Hill-start assist control (vehicles with an automatic transmission)
Prevents the vehicle from rolling backwa rds when starting on an incline or
slippery slope.
■ EPS (Electric Power Steering)
Employs an electric motor to reduce the amount of effort needed to turn
the steering wheel.

187
2-4. Using other driving systems
2
When drivingWhen the VSC/TRAC/hill-start assist control systems are operating
If the vehicle is in danger of slip-
ping, rolling backwards when
starting on an incline, or if the rear
wheels (2WD) or 4 wheels
(AWD) spin, the slip indicator light
flashes to indicate that the VSC/
TRAC/hill-start assist control sys-
tems have been engaged.
A buzzer (intermittent) sounds to
indicate that VSC is operating.
The stop lights and high mounted
stoplight turn on when the hill-start
assist control system is operating.
■VDIM (Vehicle Dynamics Integrated Management)
Provides integrated control of the ABS, brake assist, TRAC, VSC, hill-start
assist control, and EPS systems.
Maintains vehicle stability when swerving on slippery road surfaces by
controlling the brakes and engine output.
■ PCS (Pre-Collision System) (if equipped)
 P. 1 9 2

192
2-4. Using other driving systems
PCS (Pre-Collision System)
Radar sensorDetects vehicles or other obsta-
cles on or near the road ahead and
determines whether a collision is
imminent based on the position,
speed, and heading of the obsta-
cles. Grille cover
Radar sensor
Safety systems such as the brakes and seat belts are automatically
engaged to lessen impact and injuries to occupants as well as vehicle dam-
age when the radar sensor detects an unavoidable frontal collision.
■Pre-collision seat belts
The seat belts are immediately retracted to provide the driver and passen-
gers with enhanced pretensioner effectiveness in a collision. ( P. 5 7 ) I n
the event of sudden braking or skiddi ng, the system will operate even if no
obstacle has been detected.
■ Pre-collision brake assist
Applies greater braking force in relation to how strongly the brake pedal is
depressed.
■Obstacles not detected
The sensor cannot detect plastic obstacles such as pylons. There may also be occa-
sions when the sensor cannot detect pedestrians, animals, bicycles, motorcycles,
trees, or snowdrifts.
: If equipped

193
2-4. Using other driving systems
2
When driving
■The pre-collision system is operational when
●Pre-crash seat belt (linked to the radar sensor)
• Vehicle speed is above 3 mph (5 km/h).
• The speed at which your vehicle is approaching the obstacle or oncomingvehicle exceeds 18 to 24 mph (30 to 40 km/h).
• The front occupants are wearing a seat belt.
●Pre-crash seat belts (linked to brake operation)
• Vehicle speed exceeds 18 mph (30 km/h).
• The system detects sudd en braking or skidding.
• The front occupants are wearing a seat belt.
●Pre-crash brake Assist
• Vehicle speed is above 18 mph (30 km/h).
• The speed at which your vehicle is approaching the obstacle or the vehicle is greater than 18 to 24 mph (30 to 40 km/h).
• The brake pedal is depressed.
■Conditions that may trigger the system even if there is no danger of 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 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.
■When there is a malfunction in the system
Warning lights and/or warning mess ages will turn on or flash. (P. 383, 392)

200
2-5. Driving information
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 coolant
• Washer fluid
● Have a service technician inspect the level and specific gravity of
battery electrolyte.
● Have the vehicle fitted with four snow tires or purchase a set of
tire chains for the rear tires.
Ensure that all tires are the specified size and the same brand, and that
chains match the size of the tires.
■ Before driving the vehicle
Perform the following according to the driving conditions.
● Do not try to forcibly open a window 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.