brakes Lexus GS450h 2008 Do-it-yourself maintenance / LEXUS 2008 GS450H OWNER'S MANUAL (OM30A96U)

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2-1. Driving procedures
2
When driving
GS_HV_U
May 13, 2008 3:11 pm
■Driving in the rain
●Drive carefully when it is raining, because visibility will be reduced, the windows
may become fogged-up, and the road will be slippery.
●Drive carefully when it starts to rain, be cause the road surface will be especially
slippery.
●Refrain from high speeds when driving on an expressway in the rain, because
there may be a layer of wate r between the tires and the road surface, preventing
the steering and brakes from operating properly.
■Breaking in your new Lexus
To extend the life of the vehicle, the following precautions are recommended to
observe:
●For the first 186 miles (300 km): 
Avoid sudden stops.
●For the first 621 miles (1000 km):
• Do not drive at extremely high speeds.
• Avoid sudden acceleration.
• Do not drive continuously in the low range in the “S” position.
• Do not drive at a constant speed for extended periods.
■Operating your vehicle in a foreign country
Comply with the relevant vehicle registration laws and confirm the availability of the
correct fuel. ( P. 5 4 6 )

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2-1. Driving procedures
GS_HV_U
May 13, 2008 3:11 pm
CAUTION
■When driving the vehicle
●Do not shift the shift lever to “N” while the vehicle is moving.
Doing so may cause the engine brake not to operate properly and lead to an
accident.
●Do not turn the hybrid system off while driving. 
The power steering and brake actuator will not operate properly if the hybrid sys-
tem is off.
●Use engine braking (downshift) to maintain a safe speed when driving down a
steep hill. 
Using the brakes continuously may cause the brakes to overheat and lose effec-
tiveness. ( P. 144)
●When stopped on an inclined surface, use the brake pedal and parking brake to
prevent the vehicle from rolling backwa rd or forward and causing an accident.
●Be careful when driving on slippery surfaces, as the vehicle may spin or skid when
downshifting, rapidly accelerating, braking or turning.
●Do not adjust the position of the steering wheel, the seat, or the inside or outside
rear view mirrors while driving. 
Doing so may result in a loss of vehicle control that can cause accidents that may
result in death or serious injury.
●Always check that all passengers’ arms, heads or other parts of their bodies are
not outside the vehicle, as this may result in death or serious injury.
●Do not drive in excess of the speed limit. Even if the legal speed limit permits it, do
not drive over 85 mph (140 km/h) unless your vehicle has high-speed capability
tires. Driving over 85 mph (140 km/h) may result in tire failure, loss of control and
possible injury. Be sure to consult a tire dealer to determine whether the tires on
your vehicle are high-speed capability tires or not before driving at such speeds.
●The driver should pay attention to pedest rians when the vehicle is powered only
by the electric motor (traction motor). Because there is no engine sounds, the
pedestrians may misjudge the vehicle’s movement.

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2-1. Driving procedures
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When driving
GS_HV_U
May 13, 2008 3:11 pm
CAUTION
■When driving on slippery road surfaces
●Sudden braking, acceleration and steering may cause tire slippage and reduce
your ability to control the vehi cle, resulting in an accident.
●Sudden changes in engine speed, such as engine braking caused by up-shifting
or down-shifting, may cause the vehicl e to skid, resulting in an accident.
●After driving through a puddle, lightly depress the brake pedal to make sure that
the brakes are functioning properly. Wet brake pads may prevent the brakes from
functioning properly. If the brakes on on ly one side are wet and not functioning
properly, steering control may be af fected, resulting in an accident.
■When shifting the shift lever
Be careful not to shift the shift lever with the accelerator pedal depressed. 
This may lead to unexpected rapid acceleration of the vehicle that may cause an
accident and result in death or serious injury.
■When the vehicle is stopped
●Do not race the hybrid system. 
If the vehicle is in any positions other than “P” or “N” the vehicle may accelerate
suddenly and unexpectedly, and may cause an accident.
●Do not leave the vehicle with the hybrid system on for a long time. 
If such a situation cannot be avoided, park the vehicle in an open space and
check that exhaust fumes do no t enter the vehicle interior.
●Always keep a foot on the brake pedal while the hybrid system is operating to
prevent an accident caused by the vehicle moving.

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2-1. Driving procedures
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When driving
GS_HV_U
May 13, 2008 3:11 pm
CAUTION
■When taking a nap in the vehicle
Always turn the hybrid system off. Otherwise, you may accidentally move the shift
lever or depress the accelerator pedal, which could cause an accident or fire due to
hybrid system overheating. Additionally, if the vehicle is parked in a poorly venti-
lated area, exhaust gases may collect and enter the vehicle, leading to death or a
serious health hazard.
■When braking the vehicle
●When the brakes are wet, drive more cautiously.
Braking distance increases when the brakes are wet, and may cause one side of
the vehicle to brake differently than the other side. Also the parking brake may
not securely hold the vehicle.
●If the brake actuator does not operate, do not follow other vehicles closely and
avoid downhill or sharp turns that require making. 
In this case, braking is still possible, but it will require more force on the pedal than
usual. Braking distance may also increase.
●Do not pump the brake pedal if turning the hybrid system off. 
Each push on the brake pedal uses up th e reserve for the power-assisted brakes.
●The brake system consists of 3 individual hydraulic systems: If one of the systems
fails, the other will still operate. In this case, the brake pedal should be depressed
more firmly than usual and braking distance becomes longer. 
Do not drive your vehicle with only a single brake system. Have your brakes fixed
immediately.

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2-4. Using other driving systems
GS_HV_U
January 4, 2008 10:02 am
Cruising in vehicle-to-vehicle distance control mode This mode employs a radar sensor to detect the presence of vehicles
within 400 ft. (120 m) ahead and to judge the distance between your
vehicle and those vehicles.
Note that vehicle-to-vehicle distance will close when trave ling on long down-
hill 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-vehi-
cle distance can also be set by oper ating the vehicle-to-vehicle distance
switch.
Example of deceleration cruising 
When the vehicle ahead is driving slower than the set speed
When a vehicle is detected running ahead of you, in the same lane, the sys-
tem automatically decelerates 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 sufficiently to prevent your
vehicle from closing on the vehicle ahead.

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2-4. Using other driving systems
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When driving
GS_HV_U
January 4, 2008 10:02 am
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 dis-
tance set by the driver.
Example of acceleration 
When there are no longer vehicles driving slower than the set speed in
the lane ahead
When the vehicle ahead of you executes a lane change, the system slowly
accelerates until the set vehicle speed is reached. The system then returns to
fixed speed cruising.
Approach warning
When your vehicle is too close to a vehicle ahead, and sufficient auto-
matic deceleration via the cruise cont rol is not possible, the display will
flash and buzzer will sound to alert th e 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 appr opriate vehicle-to-vehicle distance.
■Warning lights and messages for dynamic radar cruise control
Warning lights, messages and buzzers are us ed to indicate a system malfunction or
to inform the driver of the need for caution while driving. ( P. 5 0 2 )
■Switching modes
The mode cannot be switched to constant speed control mode if vehicle-to-vehicle
distance control mode has been used. The mode also cannot be switched from
constant speed control to vehicle-to-vehic le control mode. Turn the system off by
pressing the “ON-OFF” button, and turn it on again.

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2-4. Using other driving systems
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When driving
GS_HV_U
January 4, 2008 10:02 am
CAUTION
■Before using dynamic radar cruise control
Do not overly rely on vehicle-to-vehicle distance control.
Be aware of the set vehicle speed. If au tomatic 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.
■To avoid operating the dynamic radar cruise control by mistake
Keep the “ON-OFF” button off when not in use.
■Situations unsuitable for dynamic radar cruise control
Do not use dynamic radar cruise contro l in any of the following situations.
Doing so may result in inappropriate cont rol 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, 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 (f og, snow, sandstorm, etc.)
●When the approach warning buzzer can be heard often

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2-4. Using other driving systems
GS_HV_U
January 4, 2008 10:02 am
CAUTION
■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. 509) 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
■Conditions under which the vehicle-to-vehicle distance control may not function
correctly
Apply the brakes as necessary in the foll owing 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

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2-4. Using other driving systems
GS_HV_U
January 4, 2008 10:02 am
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)
Maintains drive power and prevents the rear wheels from spinning when
starting the vehicle or accelerating on slippery roads.
■Hill-start assist control
Helps prevent the vehicle from rolling backwards when starting on an
incline or slippery slope. It operates for approximately 5 seconds at maxi-
mum.
■ EPS (Electric Power Steering)
Employs an electric motor to reduce the amount of effort needed to turn
the steering wheel.
■Active stabilizer suspension system (if equipped)
Turns at smaller angles to main tain the stable vehicle posture.

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2-4. Using other driving systems
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When driving
GS_HV_U
January 4, 2008 10:02 am
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.