2008 Lexus GS450h Scheduled Maintenace Guide / LEXUS 2008 GS450H OWNER'S MANUAL (OM30A96U)

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When 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 incli ne, or if the rear
wheels 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.
The slip indicator light flashes as
well when ABS is operating.
■ PCS (Pre-Collision System) (if equipped)
 P. 2 0 6
■VGRS (Variable Gear Ratio Steering)
Adjusts the wheel turning angle in accordance with the vehicle speed and
steering wheel movement.
■VDIM (Vehicle Dynamics Integrated Management)
Provides integrated control of the AB S, VSC, TRAC, hill-start assist con-
trol, VGRS and EPS systems. 
Maintains vehicle stability when swerving on slippery road surfaces by
controlling the brakes, hybrid output, and the movement of the front
wheels.

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To disable TRAC and/or VSCIf the vehicle gets stuck in fresh snow or mud, TRAC and VSC may
reduce power from the engine to th e wheels. You may need to turn the
system off to enable you to rock the vehicle in order to free it.
■ Turning off TRAC only
Quickly push and release the but-
ton to turn off TRAC.
The slip indicator light should come
on.
Push the button again to turn the
system back on.
■Turning off both TRAC and VSC
Push and hold the button for more
than 3 seconds while the vehicle is
stopped to turn off TRAC and
VSC.
The slip and VSC OFF indicator
light should come on.
Push the button again to turn the
system back on.

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■Automatic reactivation of TRAC and VSC
Turning the “POWER” switch OFF after turning off the TRAC and VSC systems will
automatically re-enable them.
■Automatic TRAC reactivation
If only the TRAC system is turned off, the TRAC system will turn on when the vehi-
cle speed increases.
■Automatic TRAC and VSC reactivation
If the TRAC and VSC systems are turned off, the systems will not turn on even when
the vehicle speed increases.
■Sounds and vibrations caused by the A BS, brake assist, VSC, TRAC, hill-start
assist control and VGRS systems
●A sound may be heard from the engine compartment when the hybrid system is
started or just after the vehicle begins to move. 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 after the ABS is activated.
■Hill-start assist control operating conditions
This system comes into operation under the following conditions after the brake
pedal has been depressed and the vehicle has come to a stop:
●The shift lever is in the “D” or “S”.
●The system has detected that the vehicle is moving backwards.

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■Reduced effectiveness of EPS
The effectiveness of EPS 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 hybrid system off. The system should return to normal
about 10 minutes.
■VGRS is disabled in the following situations
●During stopping or the steering wheel has been moved for a long time while
driving at lower speeds.
●After the hybrid system is restarted at less than -22°F (-30°C).
CAUTION
Any of the following conditions may result in an accident which could cause death or
serious injury:
■The ABS does not operate effectively when
●The limits of tire gripping performance have been exceeded.
●The vehicle hydroplanes while driving at high speed on the 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 roads
■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 is operating. 
Do not drive the vehicle in conditions where stability and power may be lost.

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CAUTION
■The hill-start assist control may not operate effectively when
●On steep inclines.
●On icy surfaces.
■When the VSC is activated
The slip indicator light flashes and a warning buzzer sounds. Always drive carefully.
Reckless driving may cause an accident. Ex ercise particular care when the indica-
tor light flashes and a buzzer sounds.
■When TRAC and VSC are off
Be especially careful and drive at a speed appropriate to the road conditions. As
these are systems to ensure vehicle stability and driving force, do not turn off TRAC
and VSC unless necessary.
■Replacing tires
Make sure that all tires are of the same size, brand, tread pattern and total load
capacity. In addition, make sure that the ti res are inflated to the specified tire pres-
sure level.
The ABS and VSC will not function correctly if different tires are fitted on the vehi-
cle. 
Contact your Lexus dealer for further info rmation when replacing tires or wheels.
■Handling of tires and suspension
Using tires with any kind of problem or modifying the suspension will affect the driv-
ing assist systems, and may cause the system to malfunction.

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PCS (Pre-Collision System) (if equipped)
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 (front seats only)
The seat belts are immediately retracted as the effect of the pretensioner is
increased ( P. 67), to help prepare the driver and passengers. In the
event of sudden braking or skidding, 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.
■ Pre-collision AVS
If the system determines that the collision is unavoidable, the operation of
AV S ( P. 199) helps prevent the vehicle front from going down when
hard brakes are applied.

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■Obstacles not detected
The sensor cannot detect plastic obstacles such as pylons. There may also be occa-
sions when the radar sensor cannot detect pedestrians, animals, bicycles, motorcy-
cles, trees, or snowdrifts.
■The pre-collision system is operational when
●Seat belts (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 oncoming vehicle exceeds 18 mph (30 km/h).
• The front occupants are wearing a seat belt.
●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.
●Brake assist
• Vehicle speed is above 18 mph (30 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming vehicle exceeds 18 mph (30 km/h).
• The brake pedal is depressed.
●AV S
• Vehicle speed is above 3 mph (5 km/h).
• The speed at which your vehicle is approaching the obstacle or oncoming vehicle exceeds 18 mph (30 km/h).

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■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 messages will turn on or flash. ( P. 492, 502)