2010 Lexus HS250h wheel

217
2-4. Using other driving systems
2
When driving
LKA (Lane-Keeping Assist)
: If equipped
While driving on a freeway or motor highway that has lane markers, this
system recognizes the lanes using a camera as a sensor to assist the driver
with staying in the lane. The LKA system has two functions.
■Lane departure warning function
If the system judges that the vehicl e may deviate from its lane, it
alerts the driver using rapid beepin g, indications on the multi-infor-
mation display, and a sensory warning
* given via the steering wheel.
*: A slight steering torque is applied for a short period of time in the
direction of the center of the lane.
■ Lane keeping assist function
This function will be active when the vehicle-to-vehicle distance
control mode of the cruise control ( P. 205) is set with vehicle
speed above approx. 45 mph (approx . 72 km/h) and while the lane
departure warning function is acti ve. When the lane keeping assist
function is active, a slight steering torque will be applied, to help the
driver maintain the vehicle inside the lane.

220
2-4. Using other driving systems
Indication on the multi-information display
While the LKA system is on, the lane line display and steering wheel dis-
play (in case of lane k eeping as
sist function) are shown on the multi-infor -
mation display to inform that the LKA system is on.
Steering wheel display
The lane keeping assist function is
active.
Dynamic radar cruise control
display
Lane line display
When thin lines are shown:
A lane marker is not recognized by
the s
ystem, or the LKA system
functions are temporarily can -
celed. (When the lane keeping
as
sist function is canceled, buzzer
will beep twice.)
When solid lane lines are shown: 
The lane departure warning func -
tion is active.
■Temporary cancellation of the LKA system functions
If any of the following occurs, the LKA sy stem
functions will be temporarily can-
celed. The functions will resume after the necessary operating conditions have
re
turned.
●The turn signal le ver is operated.
●The steering wheel is turned as far as necessary to cause the vehicle to change
lanes.
●The brake pedal is depressed. 
However, the lane keeping assist function will not resume even after the brake
pe
dal is released because depressing the brake pedal also cancels the dynamic
radar cruise control. (only lane departure warning function will resume)

221
2-4. Using other driving systems
2
When driving
●The vehicle speed deviates from the operating range of the LKA system func-
tions.
●When the lane lines cannot be recognized while driving.
●Low speed or high speed wiper operation states. 
The buzzer may not beep when the LKA system functions are canceled
because the notification of dynamic radar cruise control cancellation takes pri-
ority over the LKA system and cancels the function.
●The no-handed driving warning activates while the lane keeping assist function
is active. (The buzzer will beep twice.)
■No-handed driving warning
If the steering wheel is not operated for about 15 seconds on a straight road or
about 5 seconds on a curve, the buzzer will beep twice, indicators on the multi-
information display will flash, and the lane keeping assist function will be temporarily
canceled. If you drive the vehicle with your hands lightly touching the steering
wheel, this may also be detected as no-handed driving.
■When the vehicle has been parked in the sun
The LKA system functions may not be available for a while after driving has started.
In such cases, turn the LKA system off and turn it on again after normal temperature
returns. When the temperature in the cab in decreases and the temperature around
the camera sensor becomes suitable for it s operation, the functions will begin to
operate.
■Warning lights and messages for LKA
Warning lights and messages ar e used to indicate a system malfunction or to inform
the driver of the need for caution while driving. ( P. 493, 505)

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2-4. Using other driving systems
CAUTION
■Before using the LKA system
Do not rely on the LKA system to remain within a selected lane. The LKA system is
not designed to enable inattentive driving. The steering wheel should be operated
by the driver to maintain the vehicle in a suitable position within its lane. Always
drive carefully.
■Turn the LKA off while driving in any of the following conditions:
Do not use LKA in any of the following situations. 
Otherwise, the system may not function correctly and could result in an accident.
●When driving with snow ti res, snow chains, a spare tire, or similar equipment.
●When driving with non-standard parts or aftermarket equipment installed.
(including modified tires and suspensions, etc.)
●When towing a trailer.
●When there are objects or structures alon g the roadside that might be misinter-
preted as lane markers. (such as guardrails, curb, reflector posts, etc.)
●Where there are wheel ruts, icy trademarks, etc. or if snow remains on the road
surface.
●When there are shadows on the road running parallel with lane markers, or if a
shadow covers the lane markers.
●When there are visible lines on the pavement from road repairs, or if the remains
of old lane markers are still visible on the road.
●When driving on slippery roads, such as those covered with rain, ice or snow.
●When driving in a lane other than the driving or passing lanes on a freeway or
highway.
●When driving on a road with lane closur es due to maintenance, or when driving
in a temporary lane.
●When driving on winding roads or roads that are rough or uneven.

225
2-4. Using other driving systems
2
When driving
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 wh en swerving suddenly or turning on
slippery road surfaces
■ TRAC (Traction Control)
Helps to maintain drive power and prevents the drive wheels from spin -
ning when starting the vehicle or
accelerating on slippery roads
■EPS (Electric Power Steering)
Employs an electric motor to reduce the amount of effort needed to turn
the steering wheel
■Enhanced VSC (Enhanced vehicle stability control)
Provides cooperative control of the ABS, TRAC, VSC and EPS. 
Helps to maintain directional stability when swerving on slippery road sur -
faces by controlling steering performance.
■ PCS (Pre-Collision System) (if equipped)
 P. 2 3 3

226
2-4. Using other driving systems
When the VSC/TRAC systems are operating
If the vehicle is in danger of slip-
ping or if any of the drive wheels
spins, the slip indicator light flashes
to indicate that the V

SC/TRAC
systems are operating.
A buzzer (intermittent) sounds to
indicate that VSC is operating.
Disabling the TRAC/VSC systems
If the vehicle gets stuck in fresh snow or mud, the TRAC and VSC sys -
tems may reduce power from the hybr id sy
stem to the wheels. You may
need to turn the system off to enable you to rock the vehicle in order to
free it.
■ T
urning off the TRAC system only
To turn the TRAC system off,
quickly pr
ess and release the but -
ton.
A message will be shown on the
multi-information display.
Press the button again to turn the
sy
stem back on.

227
2-4. Using other driving systems
2
When driving
■Turning off both TRAC and VSC systems
To turn the TRAC and VSC sys-
tems off, press and hold the button
for mor
e than 3 seconds while the
vehicle is stopped.
A message will be shown on the
multi-information display and
“VSC OFF” indicator will come on.
Press the button again to turn the
sy
stems back on.
■Sounds and vibrations caused by the ABS, brake assist, VSC and TRAC
●A sound may be heard from the engine compartment when the hybrid system is
started, just after the vehicle begins to move, if the brake pedal is depressed
repeatedly, or 1-2 minutes after the hybrid system is stopped. This sound does
not indicate that a malfunction has occurred in any of these systems.
●Any of the following conditions may occur when the above systems are operat -
ing. None of these indicates that a malfunction has occurred.
• Vibrations may be felt through the vehicle body and steering.
• A motor sound may be heard after the vehicle comes to a stop.
• The brake pedal may pulsate slightly after the ABS is activated.
• The brake pedal may move down s lightly af
ter the ABS is activated.
■EPS operation sound
When the steering wheel is operated, a motor soun
d (whirring sound) may be
heard. This does not indicate a malfunction.
■Reactivation of the TRAC /VSC systems
Turning off the hybrid system after turning off the TRAC/VSC systems will automat -
ically reactivate them.
■Reactivation of the TRAC sy stem linked to vehicle speed
When only the TRAC system is turned of
f, the TRAC system will turn on when vehi -
cle speed increases. However, when both TR
AC and VSC systems are turned off,
the systems will not turn on even when vehicle speed increases.

228
2-4. Using other driving systems
■Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the system from over-
heating when there is frequent steering input over an extended period of time. The
steering wheel may feel heavy as a result. Should this occur, refrain from excessive
steering input or stop the vehicle and turn the hybrid system off. The EPS system
should return to normal within 10 minutes.
CAUTION
■The ABS does not operate effectively when
●Tires with inadequate gripping ability are used (such as excessively worn tires on
a snow covered road).
●The vehicle hydroplanes while driving at high speed on wet or slick road.
■Stopping distance when the ABS is operating will exceed that of normal condi-
tions
The ABS is not designed to shorten the vehicle’s stopping dist ance. Always main-
tain a safe distance from the vehicle in front of you in the following situations:
●When driving on dirt, gravel or snow-covered roads
●When driving with tire chains
●When driving over bumps in the road
●When driving over roads with potholes or roads with uneven surfaces
■TRAC may not operate effectively when
Directional control and power may not be ac hievable while driving on slippery road
surfaces, even if the TRAC system is operating. 
Do not drive the vehicle in conditions where stability and power may be lost.
■When the VSC is activated
The slip indicator light flashes and a warning buzzer sounds. Always drive carefully.
Reckless driving may cause an accident. Exercise particular care when the indica-
tor light flashes and a buzzer sounds.
■When the TRAC/VSC systems are turned off
Be especially careful and drive at a speed appropriate to the road conditions. As
these are the systems to ensure vehicle stability and driving force, do not turn the
TRAC/VSC systems off unless necessary.