2014 Lexus IS250 Owner's Manual

2334-5. Using the driving support systems
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This mode employs a radar sensor to detect the presence of vehicles up to
approximately 120 m (400 ft.) ahead, determines the current vehicle-to-vehicle
following distance, and operates to maintain a suitable following distance from
the vehicle ahead.
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-vehicle dis-
tance can also be set by operating the vehicle-to-vehicle distance control.
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 deceler-
ates your vehicle. When a greater reduction in vehicle speed is necessary, the system
applies the brakes. A warning tone warns you when the system cannot decelerate suf-
ficiently to prevent your vehicle from closing in on the vehicle ahead.
Example of follow-up cruising
When following a vehicle driving slower than the set speed
The system continues follow-up cruising while adjusting for changes in the speed of
the vehicle ahead in order to maintain the vehicle-to-vehicle distance set by the driver.
Example of acceleration
When there are no longer any vehicles ahead driving slower than the set
speed
The system accelerates until the set speed is reached. The system then returns to con-
stant speed cruising.
Driving in vehicle-to-vehicle distance control mode
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When your vehicle is too close to a vehicle ahead, and sufficient automatic
deceleration via the cruise control is not possible, the display will flash and the
buzzer will sound to alert the driver. An example of this would be if another driver
cuts in front of you while you are following a vehicle. Apply the brakes to ensure
an appropriate vehicle-to-vehicle distance.
■Wa r n i n g s m a y n o t o c c u r w h e n
In the following instances, there is a possibility that the warnings will not occur:
●When the speed of the vehicle ahead matches or exceeds your vehicle
speed
●When the vehicle ahead is traveling at an extremely slow speed
●Immediately after the cruise control speed was set
●At the instant the accelerator is applied
When constant speed control mode is selected, your vehicle will maintain a set
speed without controlling the vehicle-to-vehicle distance. Select this mode only
when vehicle-to-vehicle distance control mode does not function correctly due
to dirt etc.
Press the “ON/OFF” button to acti-
vate the cruise control.
Press the button again to deactivate the
cruise control.
Switch to constant speed control
mode.
(Push the lever forward and hold for
approximately 1 second.)
Constant speed control mode indicator will come on.
When in constant speed control mode, to return to vehicle-to-vehicle distance con-
trol mode, push the lever forward again and hold for approximately 1 second.
After the desired speed has been set, it is not possible to return to vehicle-to-vehicle
distance control mode.
If the engine switch is turned off and then turned to IGNITION ON mode again, the
vehicle will automatically return to vehicle-to-vehicle distance control mode.
Adjusting the speed setting: →P. 2 2 6
Canceling and resuming the speed setting: →P. 2 2 6
Approach warning
Selecting conventional constant speed control mode
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2354-5. Using the driving support systems
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■Dynamic radar cruise control can be set when
●The shift lever is in D.
●Range 4 or higher of D has been selected by using the paddle shift.
●Vehicle speed is above approximately 50 km/h (30 mph).
■Accelerating after setting the vehicle speed
The vehicle can accelerate normally. After acceleration, the set speed resumes. How-
ever, during vehicle-to-vehicle distance control mode, the vehicle speed may decrease
below the set speed in order to maintain the distance to the vehicle ahead.
■Automatic cancelation of vehicle-to-vehicle distance control
Vehicle-to-vehicle distance control driving is automatically canceled in the following situ-
ations:
●Actual vehicle speed falls below approximately 40 km/h (25 mph).
●VSC is activated.
●TRC is activated for a period of time.
●When the VSC or TRC system is turned off by pressing the VSC OFF switch.
●The sensor cannot operate correctly because it is covered in some way.
●The windshield wipers are operating at high speed (when the wipers are in AUTO
mode or the high speed wiper operation).
●When snow mode is set.
●Pre-crash braking is activated.
If vehicle-to-vehicle distance control driving is automatically canceled for any other rea-
son, there may be a malfunction in the system. Contact any authorized Lexus dealer or
repairer, or another duly qualified and equipped professional.
■Automatic cancelation of constant speed control
The cruise control will stop maintaining the vehicle speed in the following situations:
●Actual vehicle speed is more than approximately 16 km/h (10 mph) below the set vehi-
cle speed.
At this time, the memorized set speed is not retained.
●Vehicle speed falls below approximately 40 km/h (25 mph).
●VSC is activated.
●TRC is activated for a period of time.
●When the VSC or TRC system is turned off by pressing the VSC OFF switch.
●Pre-crash braking is activated.

2364-5. Using the driving support systems
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■Radar sensor and grille cover
Always keep the sensor and grille cover clean to ensure that the vehicle-to-vehicle dis-
tance control operates properly. (Some obstructions, such as snow, ice and plastic
objects, cannot be detected by the obstruction sensor.)
Dynamic radar cruise control is canceled if an obstruction is detected.
■Operation guide display
When the dynamic radar cruise control switch is operated, a guidance display is shown
on the meters for a few seconds as to how to operate the dynamic radar cruise control
switch or distance switch. (→P. 1 0 3 )
■Warning messages and buzzers for dynamic radar cruise control
Warning messages and buzzers are used to indicate a system malfunction or to inform
the driver of the need for caution while driving. (→P. 4 8 6 ) Grille cover
Radar sensor
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■Certification

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CAUTION
■Before using dynamic radar cruise control
Do not overly rely on vehicle-to-vehicle distance control.
Be aware of the set speed. If automatic deceleration/acceleration is not appropriate,
adjust the vehicle speed, as well as the distance between your vehicle and vehicles
ahead by applying the brakes etc.
■Cautions regarding the driving assist systems
Observe the following precautions.
Failure to do so may cause an accident resulting in death or serious injury.
●Assisting the driver to measure following distance
The dynamic radar cruise control is only intended to help the driver in determining
the following distance between the driver’s own vehicle and a designated vehicle
traveling ahead. It is not a mechanism that allows careless or inattentive driving, and it
is not a system that can assist the driver in low-visibility conditions. It is still necessary
for driver to pay close attention to the vehicle’s surroundings.
●Assisting the driver to judge proper following distance
The dynamic radar cruise control determines whether the following distance
between the driver’s own vehicle and a designated vehicle traveling ahead is appro-
priate 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 determine whether or not
there is a possibility 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 traveling 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 control in any of the following situations.
Doing so may result in inappropriate speed control and could cause an accident result-
ing in death or serious injury.
●In heavy traffic
●On roads with sharp bends
●On winding roads
●On slippery roads, such as those covered with rain, ice or 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, snow, sandstorm, heavy rain, etc.)
●When an approach warning buzzer is heard often
●When your vehicle is towing a trailer or during emergency towing

2404-5. Using the driving support systems
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CAUTION
■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. 234) 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 (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 cor-
rectly
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 a the surrounding vehicles hinders the functioning
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.
Otherwise, the system may not function correctly and could result in an accident.
●Keep the sensor and grille cover clean at all times.
Clean the sensor and 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 sen-
sor or surrounding area is subject to a strong impact, always have the area inspected
and adjusted by any authorized Lexus dealer or repairer, or another duly qualified
and equipped professional.
●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.