2015 Lexus IS250 Owner's Manual

2404-5. Using the driving support systems
IS350/250_U (OM53C50U)
◆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
◆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.
◆TRAC (Traction Control)
Helps to maintain drive power and prevent the drive wheels from spinning
when starting the vehicle or accelerating on slippery roads
◆Hill-start assist control
Prevents the vehicle from rolling backward when starting on an incline or slip-
pery slope
◆VGRS (Variable Gear Ratio Steering) (if equipped)
Adjusts the front wheel turning angle in accordance with the vehicle speed
and steering wheel movement
Driving assist systems
To help enhance driving safety and performance, the following systems oper-
ate 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.

2414-5. Using the driving support systems
4
Driving
IS350/250_U (OM53C50U)
◆EPS (Electric Power Steering)
Employs an electric motor to reduce the amount of effort needed to turn the
steering wheel
◆Adaptive Variable Suspension system (if equipped)
By independently controlling the damping force of the shock absorbers for
each of the 4 wheels according to the road and driving conditions, this system
combines riding comfort with superior steering stability, and helps good vehi-
cle posture. ( →P. 2 3 8 )
◆VDIM (Vehicle Dynamics Integrated Management)
Provides integrated control of the ABS, brake assist, TRAC, VSC, hill-start
assist control, EPS and VGRS (if equipped) systems
Helps to maintain vehicle stability when swerving on slippery road surfaces by
controlling the brakes, engine output, steering assist, and if equipped with
VGRS, steering ratio
◆PCS (Pre-Collision System) (if equipped)
→P. 2 4 6
◆BSM (Blind Spot Monitor) (if equipped)
→P. 2 5 2
The slip indicator light will flash while
the TRAC/VSC systems are operating.
When the TRAC/VSC systems are operating

2424-5. Using the driving support systems
IS350/250_U (OM53C50U)
If the vehicle gets stuck in fresh snow or mud, the TRAC and VSC systems may
reduce power from the engine to the wheels. Pressing VSC OFF switch to turn
the system off may make it easier for you to rock the vehicle in order to free it.
■Turning off the TRAC system only
To turn the TRAC system off, quickly
press and release the switch.
The “TRAC OFF” will be shown on
the multi-information display. Press
the switch again to turn the system
back on.
■Turning off both TRAC/VSC systems
To turn the TRAC and VSC systems
off, press and hold the switch for
more than 3 seconds while the vehi-
cle is stopped.
The VSC OFF indicator light will
come on and the “TRAC OFF” will
be shown on the multi-information
display.
*
Press the switch again to turn the sys-
tems back on.
*: On vehicles with pre-collision system, pr e-collision brake assist and pre-collision
braking will also be disabled. The pre-co llision system warning light will come on
and the message will be shown on the multi-information display. ( →P. 2 4 6 )
Disabling the TRAC/VSC systems

2434-5. Using the driving support systems
4
Driving
IS350/250_U (OM53C50U)
■VGRS is disabled when
VGRS may stop operating in the following situations.
In this event, the steering wheel may move from its straight forward position, but it will
return when the system restarts.
●When the steering wheel is operated for an extended period of time while the vehicle is
stopped or is moving very slowly
●When the steering wheel has been held fully to the left or right
The center position of the steering wheel may change when VGRS is disabled. However,
the position will return to normal after VGRS is reactivated.
■When the battery is disconnected
The steering wheel may move from its straight forward position, but this will be corrected
automatically when driving.
■Sounds and vibrations caused by the ABS, brake assist, VSC, TRAC, hill-start assist
control and VGRS systems
●A sound may be heard from the engine compartment when the brake pedal is
depressed repeatedly, when the engine is started or just after the vehicle begins to
move. This sound does not indicate that a malfunction has occurred in any of these sys-
tems.
●Any of the following conditions may occur when the above systems are operating.
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 slightly after the ABS is activated.
■EPS and VGRS operation sound
When the steering wheel is operated, a motor sound may be heard. This does not indi-
cate a malfunction.
■Reactivation of the TRAC/VSC systems
Even after the TRAC/VSC systems have been turned off, turning the engine off and then
on again will automatically reactivate the TRAC/VSC systems.
■Reactivation of the TRAC system linked to vehicle speed
When only the TRAC system is turned off, the TRAC system will turn on when vehicle
speed increases. However, when both TRAC/VSC systems are turned off, the systems
will not turn on even when vehicle speed increases.

2444-5. Using the driving support systems
IS350/250_U (OM53C50U)
■Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the system from overheating
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 engine off. The EPS system should return to normal
within 10 minutes.
■Operating conditions of hill-start assist control
When the following four conditions are met, the hill-start assist control will operate:
●The shift lever is in a position other than P or N (when starting off forward/backward on
an upward incline).
●The vehicle is stopped.
●The accelerator pedal is not depressed.
●The parking brake is not engaged.
■Automatic system cancelation of hill-start assist control
The hill-start assist control will turn off in any of the following situations:
●The shift lever is moved to P or N.
●The accelerator pedal is depressed.
●The parking brake is engaged.
●Approximately 2 seconds elapse after the brake pedal is released.

2454-5. Using the driving support systems
4
Driving
IS350/250_U (OM53C50U)
CAUTION
■The ABS does not operate effectively when
●The limits of tire gripping performance have been exceeded (such as excessively
worn tires on a snow covered road).
●The vehicle hydroplanes while driving at high speed on wet or slick roads.
■Stopping distance when the ABS is operat ing may exceed that of normal conditions
The ABS is not designed to shorten the vehicle’s stopping distance. Always maintain a
safe distance from the vehicle in front of you, especially 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 uneven surfaces
■TRAC may not operate effectively when
Directional control and power may not be achievable while driving on slippery road
surfaces, even if the TRAC system is operating.
Drive the vehicle carefully in conditions where stability and power may be lost.
■Hill- start assist control does not operate effectively when
●Do not overly rely on hill-start assist control. Hill-start assist control may not operate
effectively on steep inclines and roads covered with ice.
●Unlike the parking brake, hill-start assist control is not intended to hold the vehicle
stationary for an extended period of time. Do not attempt to use hill-start assist con-
trol to hold the vehicle on an incline, as doing so may lead to an accident.
■When the VSC is activated
The slip indicator light flashes. Always dr ive carefully. Reckless driving may cause an
accident. Exercise particular care when the indicator light flashes.
■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 help ensure vehicle st ability and driving force, do not turn the
TRAC/VSC systems off unless necessary.
■Replacing tires
Make sure that all tires are of the specified size, brand, tread pattern and total load
capacity. In addition, make sure that the tires are inflated to the recommended tire infla-
tion pressure level.
The ABS, TRAC and VSC systems will not function correctly if different tires are
installed on the vehicle.
Contact your Lexus dealer for further information when replacing tires or wheels.
■Handling of tires and the suspension
Using tires with any kind of problem or modi fying the suspension will affect the driving
assist systems, and may cause a system to malfunction.

2464-5. Using the driving support systems
IS350/250_U (OM53C50U)
◆ Pre-collision warning
When a high possibility of a frontal
collision is detected, the pre-colli-
sion system warning light flashes, a
buzzer sounds and a message is
shown on the multi-information dis-
play to urge the driver to take eva-
sive action.
◆Pre-collision brake assist
When there is a high possibility of a frontal collision, the system applies
greater braking force in relation to how strongly the brake pedal is depressed.
The system may not warn the driver usin g a warning light, warning display and
buzzer when the system detects and judges braking operations.
◆Pre-collision braking
When there is a high possibility of a frontal collision, the system warns the
driver using a warning light, warning display and buzzer. If the system deter-
mines that a collision is unavoidable, the brakes are automatically applied to
reduce the collision speed.
◆Suspension control (vehicles with Adaptive Variable Suspension System)
When the system determines that there is a high possibility of a frontal colli-
sion, the operation of Adaptive Variable Suspension System ( →P. 2 4 1 ) o p t i -
mally controls the damping force of the shock absorber.
PCS (Pre-Collision System)∗
∗
: If equipped
When the radar sensor detects the possibility of a frontal collision, brakes are
automatically engaged to lessen impa ct as well as vehicle damage.
The pre-collision system can be turned on and off as necessary by operating
the switch. ( →P. 2 4 7 )

2474-5. Using the driving support systems
4
Driving
IS350/250_U (OM53C50U)
Enabled
Disabled
The pre-collision system warning light
comes on when pre-collision system is
disabled.
The radar sensor detects vehicles or
other obstacles on or near the road
ahead and determines whether a colli-
sion is imminent based on the position,
speed, and heading of the obstacles.
Disabling pre-collision system
1
2
Radar sensor