2006 Lexus GS300 Starting and Driving

STARTING AND DRIVING
427
BRAKE SYSTEM
This brake system has 2 independent hydraulic circuits. If
either circuit should fail, the other will still work. However, the
pedal will be harder to press, and your stopping distance will
increase. Also, the brake system warning light may come on.
CAUTION
Do not drive your vehicle with only a single brake
system. Have your brakes fixed immediately.
Brake booster
The brake booster uses brake fluid pressurized by the pump
(GS430) or engine vacuum (GS300) to power−assist the
brakes. If the brake booster fails during driving, the brake
system warning light (red) comes on. In this case, the brakes
may not work properly. If they do not work well, depress the
brake pedal firmly. If the brake system warning light (red)
comes on, immediately stop your vehicle and contact your
Lexus dealer.
GS430 only—Either of the following conditions may
occur, but does not indicate a malfunction:
The brake system warning light (red) may stay on for about
60 seconds after the engine is started. It is normal if the light
turns off after a while.
Depressing the brake pedal repeatedly may turn on the
brake system warning light (red). It is normal if the light goes
out after a few seconds.GS430:
You may hear a small sound in the engine compartment after
the engine is started or the brake pedal is depressed
repeatedly. This is a pump pulsating sound of the brake
system, and it is not a malfunction.
GS300:
If the engine should stop while you are driving, you can bring
the vehicle to a stop with normal pedal pressure. There is
enough reserved vacuum for one or two stops—but no more!
CAUTION
Do not pump the brake pedal if the engine stalls.
Each push on the pedal uses up your brake fluid
pressure reserve.
Even if the power assist is completely lost, the brakes
will still work. But you will have to push the pedal
hard, much harder than normal. And your braking
distance will increase.

STARTING AND DRIVING
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Anti−lock brake system
The anti−lock brake system is designed to automatically
help prevent lock−up of the wheels during a sudden
braking or braking on slippery road surfaces. This assists
in providing directional stability and steering
performance of the vehicle under these circumstances.
Effective way to press the ABS brake pedal: When the
anti−lock brake system function is in action, you may feel the
brake pedal pulsating and hear a noise. In this situation, to
let the anti−lock brake system work for you, just hold the
brake pedal down more firmly. Do not pump the brake in a
panic stop. This will result in reduced braking performance.
The anti−lock brake system becomes operative after the
vehicle has accelerated to a speed in excess of approximately
10 km/h (6 mph). It stops operating when the vehicle
decelerates to a speed below approximately 5 km/h (3 mph).
Depressing the brake pedal on slippery road surfaces such as
on a manhole cover, a steel plate at a construction site, joints
in a bridge, etc. on a rainy day tends to activate the anti−lock
brake system.
You may hear a click or motor sound in the engine
compartment for a few seconds when the engine is started or
just after the vehicle begins to move. This means that the
anti−lock brake system is in the self−check mode, and does not
indicate a malfunction.When the anti−lock brake system is activated, the
following conditions may occur. They do not indicate a
malfunction of the system:
You may hear the anti−lock brake system operating and feel
the brake pedal pulsating and the vibrations of the vehicle
body and steering wheel. You may also hear the motor
sound in the engine compartment even after the vehicle is
stopped.
At the end of the anti−lock brake system activation, the
brake pedal may move a little forward.

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CAUTION
Do not overestimate the anti−lock brake system:
Although the anti−lock brake system assists in
providing vehicle control, it is still important to drive
with all due care and maintain a moderate speed and
safe distance from the vehicle in front of you, because
there are limits to the vehicle stability and effectiveness
of steering wheel operation even with the anti−lock
brake system on.
If tire grip performance exceeds its capability, or if
hydroplaning occurs during high speed driving in the
rain, the anti−lock brake system does not provide
vehicle control.
Anti−lock brake system is not designed to shorten the
stopping distance: Always drive at a moderate speed
and maintain a safe distance from the vehicle in front of
you. Compared with vehicles without an anti−lock
brake system, your vehicle may require a longer
stopping distance in the following cases:
Driving on rough, gravel or snow−covered roads.
Driving with tire chains installed.
Driving over the steps such as the joints on the road.
Driving on roads where the road surface is pitted or
has other differences in surface height.
Install all 4 tires of specified size at appropriate
pressure: The anti−lock brake system detects vehicle
speeds using the speed sensors for respective wheels’
turning speeds. The use of tires other than specified
may fail to detect the accurate turning speed resulting
in a longer stopping distance.

STARTING AND DRIVING
430“ABS” warning light
G31080

1
U.S.A. 2
Canada
GS430—The light comes on when the engine switch is
selected in “IG−ON” mode. If the anti−lock brake system and
the brake assist system work properly, the light turns off in a
few seconds after the engine is started.
GS300—The light comes on for a few seconds when the
engine switch is selected in “IG−ON” mode. It indicates the
anti−lock brake system and the brake assist system work
properly.
If either system malfunctions, the light comes on again.
When the “ABS” warning light is on, the anti−lock brake system
and the brake assist system do not operate, but the brake
system still operates conventionally.If either of the following conditions occur, this indicates a
malfunction somewhere in the components monitored by
the warning light system. Contact your Lexus dealer as
soon as possible to service the vehicle.
The light does not come on when engine switch is selected
in “IG−ON” mode.
The light remains on after the engine is started (GS430), or
remains on after the engine switch is selected in “IG−ON”
mode (GS300).
The light comes on while you are driving.
A warning light turning on briefly during operation does not
indicate a problem.
CAUTION
If the “ABS” warning light remains on together with the
brake system warning light (red), immediately stop your
vehicle at a safe place and contact your Lexus dealer.
In this case, not only the anti−lock brake system will fail
but also the vehicle will become extremely unstable
during braking.
GS430 only—Either of the following conditions may
occur, but does not indicate a malfunction:
The light may stay on for about 60 seconds after the engine
is started. It is normal if it turns off after a while.
Depressing the brake pedal repeatedly may turn on the
light. It is normal if it turns off after a few seconds.

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Drum−in−disc type parking brake system
Your vehicle has a drum−in−disc type parking brake system.
This type of brake system needs bedding−down of the brake
shoes periodically or whenever the parking brake shoes
and/or drums are replaced.
Have your Lexus dealer perform the bedding−down.
Brake assist system
When you slam the brakes on, the brake assist system
judges as an emergency stop and provides more powerful
braking for a driver who cannot hold down the brake pedal
firmly.
When you slam the brakes on, more powerful braking will be
applied. At this time, you may hear a sound in the engine
compartment and feel the vibrations of the brake pedal. This
does not indicate a malfunction.
The brake assist system becomes operative after the vehicle
has accelerated to a speed in excess of approximately 10 km/h
(6 mph). It stops operating when the vehicle decelerates to a
speed below approximately 5 km/h (3 mph).
The brake assist system may not work for about 60 seconds
after the engine is started.
For an explanation of this system’s warning light, see “ABS”
warning light on page 78 or 430.
BRAKE PAD WEAR LIMIT
INDICATORS
G31006
The brake pad wear limit indicators on your disc brakes
give a warning noise when the brake pads are worn to the
extent that replacement is required.
If you hear a squealing or scraping noise while driving, have
the brake pads checked and replaced by your Lexus dealer as
soon as possible. Expensive rotor damage can result if the
pads are not replaced when needed.
GS430 front brake only—
The high brake performance is achieved by proper wear of
brake pads and discs. As a result, the brake discs may wear
earlier than the ones on the conventional brake system.
When brake pads are replaced, brake disc thickness is
required to be measured.
It is dangerous to continue driving when brake pads and discs
have exceeded the wear limit.

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ELECTRIC POWER STEERING
SYSTEM
The electric power steering system, using an electric
motor, assists the turning of the steering wheel.
In the following cases, you may feel the steering becomes
heavy. However, the electric power steering system
warning light does not come on. (Because it is not a
malfunction.)
When maneuvering or turning frequently over a long time, the
power steering effect will be reduced to prevent the system
from overheating. Avoid turning the steering wheel, or stop the
vehicle and select the engine switch in “ACC” or “OFF” mode.
The system will become cool in about 10 minutes.
NOTICE
Frequent maneuvering and turning over a long time may
cause damage to the system in which the mechanism
prevents overheating of the electric power steering
system.
When the battery is discharged, check the battery’s condition.
If necessary, recharge or replace the battery. For details, see
“Checking battery condition” on page 571.
G31040

Electric power steering system warning light
The light comes on when the engine switch is selected in
“IG−ON” mode. If the electric power steering system works
properly, the light turns off after a few seconds. If the system
has malfunctions, the light comes on again.
If the following conditions occur, this indicates a
malfunction somewhere in the components monitored by
the warning light system. Contact your Lexus dealer as
soon as possible to service the vehicle.
The light does not come on when the engine switch is
selected in “IG−ON” mode or remains on.
The light stays on while you are driving.

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CAUTION
If the electric power steering system warning light
comes on, take your vehicle to your Lexus dealer as
soon as possible. In this case, more effort is required
for the steering wheel to turn than usual. Drive your
vehicle while firmly gripping the steering wheel.
TIRE PRESSURE WARNING
SYSTEM
G31003

Low tire pressure warning light
The light warns you that the tire inflation pressure is low.
The low tire pressure warning light comes on when the engine
switch is selected in “IG−ON” mode and goes off after a few
seconds. This means the low tire pressure warning light is
operating properly. If the tire inflation pressure becomes low,
the light comes on again. At this time, the master warning light
comes on and the message “LOW TIRE” appears on the
multi−information display.

STARTING AND DRIVING
434If the low tire pressure warning light does not go off or comes
on during driving, it indicates that tire inflation pressure is low.
Make sure there is no flat tire. If the light comes on again even
after tire inflation pressure adjustment, you may have a flat tire.
If there is not adequate air pressure in the tires, the light will not
go off.
The light may turn on due to natural causes such as natural air
leaks or tire inflation pressure changes caused by
temperature. In this case, adjusting the tire inflation pressure
will turn off the light.
The tire pressure warning system is not a substitute for
checking tire inflation pressure.
For details about adjusting the tire inflation pressure, see
“Checking tire inflation pressure” on page 539.
If the low tire pressure warning light comes on, the action you
must take is different depending on the type of tires used.Vehicles with run−flat tires:
Stop your vehicle at a safe place as soon as possible and
check that the tire inflation pressure is as specified on the tire
and loading information label. If the low tire pressure warning
light comes on even after tire inflation pressure adjustment, it
is probable that you have a flat tire. If you cannot verify the tire
inflation pressure soon, go to the nearest Lexus dealer or
authorized tire dealer at the moderate speed and do not ever
exceed 90 km/h (55 mph) and have all your vehicle’s tires
checked and adjusted. And whether there is a flat tire or not
should be also checked at this time. If any tire must be
replaced, see “If you have a flat tire” on page 468.
If your vehicle is equipped with spare tire, the spare is not
equipped with the tire pressure sensor. So, the low tire
pressure warning light remains on even if the spare tire is
mounted.
The light goes off a few minutes after air is put into the deflated
tire.