2006 Lexus GS430 engine

STARTING AND DRIVING
434Any 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.
 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.
CAUTION
Do not pump the brake pedal if the engine stalls.
Each push on the pedal uses up your reserved brake
fluid pressure.
 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.
Brake booster (GS300)
The brake booster uses engine vacuum to power −assist the
brakes. If the engine should quit 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 reserved
vacuum.
 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.
Antilock brake system
The antilock brake system is designed to automatically
help prevent lockup 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.

STARTING AND DRIVING
435
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 antilock 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.
CAUTION
Do not overestimate the antilock brake system:
Although the antilock 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 antilock
brake system on.
If tire grip performance exceeds its capability, or if
hydroplaning occurs during high speed driving in the
rain, the antilock brake system does not provide
vehicle control.
Antilock 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 antilock
brake system, your vehicle may require a longer
stopping distance in the following cases:
 Driving on rough, gravel or snowcovered roads.
 Driving with tire chains installed.
 Driving over the st eps such as the joints on the road.
 Driving on roads where the road surface is pitted or
has other differences in surface height.

STARTING AND DRIVING
436
Install all 4 tires of specified size at appropriate
pressure: The antilock 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.“ABS” warning light
G31080
 1 U.S.A. 2Canada
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.

STARTING AND DRIVING
437
If any 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 a few seconds 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 antilock 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.
Drumindisc 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 80 or 436.

STARTING AND DRIVING
439
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.
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.

STARTING AND DRIVING
440
TIRE PRESSURE WARNINGSYSTEM
The tire pressure warning system warns you that the tire
inflation pressure is low.
The tire pressure warning syst em is not a substitute for
checking n ormal tire inflation pressure. Check the tire inflation
pressure with a tire pressure gauge regularly.
CAUTION
The warning system may not activate immediately if
bursts or sudden air leakage should occur.
G31003
 Tire pressure warning light
The tire pressure warning light comes on when the engine
switch “IG−ON” mode is selected, and goes off after a few
seconds. This means the 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.
In this case, adjusting the tire inflation pressure will turn off the
light after a few minutes. If the light blinks, the tire pressure
warning system is not working properly. At this time, the
master warning light comes on and the message “CHECK
SYSTEM” appears on the multi −information display.

STARTING AND DRIVING
444If the tire pressure warning light blinks...
G31048
If the tire pressure warning light blinks when the engine
switch “IGON” mode is selected, the tire pressure
warning system is not working properly.
The system will be disabled in the following conditions:
(When the condition becomes normal, the system will work
properly.)

If tires not equipped with tire pressure warning valves and
transmitters are used.
 If the ID code on the tire pressure warning valves and
transmitters is not registered.
 If electronic devices or facilities using similar radio wave
frequencies are nearby.
 If a radio set at similar frequencies is in use in the vehicle. 
If a window tint that affects the radio wave signals is
installed.
 If the tire pressure warning select switch is set to a dif ferent
tire setting.
 If there is a lot of snow or ice on the vehicle, in particular
around the wheels or wheel housings.
 If non− genuine Lexus wheels are used.
 If tire chains are used.
 If the tire inflation pressure is more than 500 kPa (5.1
kgf/cm
2 or bar, 73 psi).
If the tire pressure warning light blinks frequently when the
engine switch “IG −ON” mode is selected, have it checked by
your Lexus dealer.
Even if you use genuine wheels, the tire pressure warning
system may not work properly with some types of tires.
Pushing the tire pressure warning reset switch should not turn
off the tire pressure warning light.

STARTING AND DRIVING
447
To initialize the system, perform the following:
1. Park
the vehicle in a safe place and select the engine switch
in “OFF” mode.
2. Adjust the pressure of all the installed tires to the specified
cold tire inflation pressure level. (See “Tire and wheels” on
pages 542 and 546.)
3. Select the engine switch in “IG −ON” mode.
4. Push and hold the tire pressure warning reset switch until
the tire pressure warning light blinks slowly three times and the
message “PRESSURE INITIAL” appears on the
multi−information display.
5. Wait for a few minutes with the engine switch in “IG −ON”
mode, and then select the engine switch in “OFF” position.
If you push the tire pressure reset switch while the vehicle is
moving, initialization is not performed.
If you push the tire pressure reset switch accidentally and
initialization is performed, adjust the tire inflation pressure to
the specified level and initialize the system again.
G31007
If the tire pressure warning light does not blink slowly three
times and the message “PRESSURE INITIAL” does not
appear on the multi −information display when you push and
hold the reset switch, initialization has failed and the tire
pressure warning system may not work properly. In this case,
initialize the system again. If initialization cannot be
performed, have the system checked at your Lexus dealer.