brakes Lexus GS450h 2007 Do-it-yourself maintenance / LEXUS 2007 GS450H THROUGH JUNE 2006 PROD. OWNER'S MANUAL (OM30727U)

97
2-1. Driving procedures
2
When driving
CAUTION
■When driving the vehicle
●Do not under any circumstances shift the shift lever to “P”, “R” or “N” while the
vehicle is moving. 
Doing so can cause significant damage to the transmission and may result in a
loss of vehicle control.
●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 brake actuator will not operate properly if the hybrid system 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. 1 0 6 )
●When stopped on an inclined surface, use the brake pedal and parking brake to
prevent the vehicle from rolling backward 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.

99
2-1. Driving procedures
2
When driving
CAUTION
■When taking a nap in the vehicle
Always turn the hybrid system off. 
Otherwise, you may accidentally move the shift lever or press the accelerator
pedal, which could cause an accident or fi re due to abnormal hybrid system over-
heating. Additionally, if the vehicle is park ed in a poorly ventilated area, exhaust
fumes may enter the vehicle and cause gas poisoning.
■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 the hybrid system is not operating. 
Each push on the pedal uses up yo ur reserved brake fluid pressure.
●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.

133
2-4. Using other driving systems
2
When driving
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 traveling on long down -
hill slopes.
Example of constant speed cruising (when there are no vehicles
ahead): When set to 62 mph (100 km/h)
The vehicle travels at the speed set by the driver. The desired vehicle-to-vehi-
cle distance can also be set by operating the vehicle-to-vehicle distance
swi
tch.
Example of deceleration cruising (wh en the vehicle ahead is driving
slower than the set speed): When fixed speed cruising is set at 6
2 mph
(100 km/h) and the vehicle ahead is driving at 50 mph (80 km/h)
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
v
ehicle speed is necessary, the system applies the brakes. A warning tone
warns you on the system cannot decelerate sufficiently to prevent your vehi -
cle from closing on the vehicle ahead.

137
2-4. Using other driving systems
2
When driving
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
●Where there are sudden changes between sharp up and down gradients
●At entrances to expressways
●When weather conditions are bad enough that they may prevent the sensors
from functioning correctly (f og, snow, sandstorm, etc.)
●Where buzzer can be heard often

138
2-4. Using other driving systems
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. 447) 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
■To ensure the radar sensor functions correctly
Do not do the following to the sensor or grille cover as doing so may cause the sen-
sor not to function correctly and could result in an accident.
●Stick or attach anything to them
●Leave them dirty
●Disassemble, subject them to strong shocks
●Modify or paint them
●Replace them with non-genuine parts

163
2-4. Using other driving systems
2
When driving
When the VSC/TRAC/hill-start assist control systems are operating
If the vehicle is in danger of slip-
ping, rolling backwards when
star
ting 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-star
t
assist control system is operating.
The slip indicator light flashes as
well when ABS is operating.
■ 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
contr
olling the brakes, engine output, and the movement of the front
wheels.
■ PCS (Pre-Collision System) (if equipped)
 P. 1 6 7

167
2-4. Using other driving systems
2
When driving
PCS (Pre-Collision System) (if equipped)
Radar sensor
Detects vehicles or other obsta-
cles on or near the road ahead and
determines whether a collision is
imminent based on the position,
sp

eed, 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 a
n 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. 4 4 ), to provide even greater constraining force to protect
the driver and passengers. In the event of sudden braking or skidding, the
s
ystem 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. 1 6 1 ) helps prevent the vehicle front from going down when hard
brakes are applied.
■Obstacles not detected
The sensor cannot detect plastic obstacles such as pylons. There may also be occa -
sions when the sensor cannot detect pedestrians, animals, bicycles, motorcycles,
tr
ees, or snowdrifts.

168
2-4. Using other driving systems
■The pre-collision system is operational when
●Seat belt (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 9 mph (15 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).
■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. 432, 439)

175
2-5. Driving information
2
When driving
■Before driving the vehicle
Perform the following according to the driving conditions.
● D
o not try to forcibly open a w indow or move a wiper that is fro-
zen. Pour warm water over the frozen ar
ea to melt the ice. Wipe
away the water immediately to prevent it from freezing.
● T
o ensure proper operation of the climate control system fan,
remove any snow that has accumulated on the air inlet vents in
front of the windshield.
● R
emove any ice that has accumul ated on the vehicle chassis.
● P
eriodically check for and remove any excess ice or snow that
may have accumulated in the wheel well or on the brakes.
■ When driving the v
ehicle
Accelerate the vehicle slowly and dr iv
e at a reduced speed suitable
to road conditions.
■ When parking the v
ehicle
Park the vehicle and move the shift lever to “P” without setting the
parking br
ake. The parking brake ma y freeze up, preventing it from
being released.

352
4-2. Maintenance
Vehicle interior
ItemsCheck points
Accelerator pedal• Moves smoothly (without uneven pedal effort or catching)?
Transmission “Park” 
mechanism• Can the vehicle be hold securely on an incline with the shift lever in
“P”?
Brake pedal
• Moves smoothly?
• Does it have appropriate clearance and correct amount of free play?
Brakes
• Pulls to one side when applied?
• Loss of brake effectiveness?
• Spongy feeling brake pedal?
• Pedal almost touches floor?
Head restraints• Move smoothly and lock securely?
Indicators/buzzers• Function properly?
Lights
• Do all the lights come on?
• Headlights aimed correctly? 
(  P. 4 1 1 )
Pa r k i n g b r a ke
• Moves smoothly?
• Can hold the vehicle securely on
an incline?
Seat belts
• Does the seat belt system operate smoothly?
• Are the belts undamaged?
Seats• Do the seat controls operate prop- erly?