brake LEXUS LS430 2005 Service Manual

STARTING AND DRIVING
367
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.
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.

STARTING AND DRIVING
368
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 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 antilock brake system detects vehicle
speeds u sing 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
31L350
 1 U.S.A. 2Canada
The light comes on when the ignition switch is turned to the
“ON” position. If the anti−lock brake system and the brake
assist system work properly, the light turns off after a few
seconds. Thereafter, if either of the systems malfunctions, the
light comes on again.
When the “ABS” warning light is on (and the brake system
warning light is off), the anti −lock brake system, the brake
assist system, the traction control system and/or the vehicle
stability control system do/does not operate, but the brake
system still operates conventionally.
When the “ABS” warning light is on (and the brake system
warning light is off), the anti− lock brake system does not
operate so that the wheels could lock up during a sudden
braking or braking on slippery road surfaces.

STARTING AND DRIVING
369
If any of the following conditions occurs, 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 ignition switch is
turned to the “ON” position, or remains on.
 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, 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.
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
If you slam the brakes on such as in an emergency or
apply the brakes more firmly than usual such as when
descending the hill with the designated number of
occupants in the vehicle, the brake assist system
provides more powerful braking.
If you slam the brakes on or apply the brakes more firmly, 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).
For an explanation of this system’s warning light, see “ABS”
warning light on page 87 or 368.

STARTING AND DRIVING
371

The degree of the tread wear is very different among the
installed tires.
 Rapid acceleration/deceleration or sharp turns are
continued.
 Towing a trailer.
 The loading is over the limit or unbalanced.
 Initialization was not performed correctly after replacing or
rotating tires or wheels.
 The outside temperature is below 0 C (32F) or above
40 C (104 F).
If the warning message appears again on the
multi−information display after adjusting tire inflation pressure,
the system may be malfunctioning. Have your vehicle
checked by your Lexus dealer as soon as possible.
CAUTION
When the tire pressure warning message appears,
observe the following instructions:
 Adjust the tire inflation pressure to the specified level
as soon as possible.
 Avoid abrupt steering wheel maneuvering and
braking. If the vehicle tires are deteriorated, you
could lose control of the steering wheel or the brakes,
causing death or serious injury.
Note: The tire pressure mon itoring system on your
vehicle will warn you when one of your tires is
significantly underinflated and when some
combinations of your tires are significantly
underinflated. However, there are other combinations
of significantly underinflated tires for which your tire
pressure warning system may not warn you. These
other combinations are relatively common, accounting
for approximately half the instances in which vehicles
have significantly underinflated tires. For example,
your system may not warn you when both tires on the
same side or on the same axle of your vehicle are
significantly underinflated. It is particularly important,
therefore, for you to check the tire inflation pressure in
all of your tires regularly and maintain proper pressure.

STARTING AND DRIVING
372
Tire pressure warning system reset switch
31L568b
The tire pressure warning system needs to be initialized
after tires or wheels are replaced or rotated.
To initialize the system, perform the following:
1. Park the vehicle at a safe place with the parking brake
applied and turn the ignition switch to “LOCK”.
2. Adjust the pressure of all the installed tires to the specified
level. (See “Tires and wheels” on pages 463 through 465.)
3. Turn the ignition switch to “ON”.
If the low tire pressure warning message “Low Tire” appears
in the multi−information display, push the reset switch for a few
seconds and make sure the warning message goes off.
4. With the vehicle stopped, push and hold the reset switch
until “Pressure Initial” appears in the multi−information display.
W266
Initialization is completed after driving at the speeds of 30
km/h (19 mph) or over for more than one hour. If the
following driving conditions are satisfied, initialization
will be completed in about one hour.
 The vehicle speeds is between 50 km/h (31 mph) and
100 km/h (62 mph).
 The roads are dry, smooth and straight.
 The number of passengers is one or two (including the
driver).
If you make a mistake in the middle of initialization, perform the
operation from the beginning again.
Do not push the reset switch without adjusting the tire inflation
pressure to the specified level. Otherwise, the low tire
pressure warning may not turn on even if the tire inflation
pressure is low, or it may turn on when the tire inflation
pressure is actually normal.
If you push the reset switch while driving, initialization is not
performed.
If “Pressure Initial”does not appear when the reset switch is
held down, the system may be malfunctioning. Have your
vehicle checked by your Lexus dealer as soon as possible.

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Tire pressure system warning message
w265
If there is a problem electrically in the tire pressure
warning system, the master warning light comes on, the
above message appears and a warning tone sounds. At
this time the multiinformation display indicates which
part causes an error.
Although it is no problem to continue driving with the above
message on the display, have your vehicle checked by your
Lexus dealer as soon as possible.
BRAKE PAD WEAR LIMITINDICATORS
13L338
 1Master warning light
2Brake pad wear warning message
When your brake pads are worn enough to require
replacement, the warning tone sounds, the master
warning light flashes and the brake pad wear warning
message in the multiinformation display appears.
If the warning message appears while driving, have the brake
pads checked and replaced by your nearest Lexus dealer
immediately.
Continuous driving without replacing the brake pads will cause
expensive rotor damage and increasing brake pedal effort to
get the same stopping distance.

STARTING AND DRIVING
376
Precollision brake assist system
When the precollision sensor detects an object or
vehicle with which your vehicle might collide, and
determines that a collision may be unavoidable,
depressing the brake pedal provides more powerful
braking according to the amount of pedal depression.
The pre−collision brake assist system will operate in the
following conditions:
 When the ignition switch is turned on.
 When the approaching speed in regard to the object or the
vehicle exceeds about 30 km/h (18 mph).
 When the brake pedal is depressed.
If the brake pedal is kept depressed before the sensor’s
determination of unavoidable collision, the pre −collision brake
assist system will operate soon after the sensor’s
determination.
Electronically modulated air suspension
control
When the precollision sensor detects an object or
vehicle with which your vehicle may collide, and
determines that a collision may be unavoidable, the
electronically modulated air suspension adjusts the
damping effect on the shock absorbers and regulates the
vehicle not to pitch forward so much.
The electronically modulated air suspension will operate in the
following conditions:
 When the ignition switch is turned on.
 When the vehicle speed is about 5 km/h (3 mph) or over.
 When the approaching speed in regard to the object or the
vehicle exceeds about 30 km/h (18 mph).

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378
Precaution for precollision safety system
It should be noted that the pre−collision sensor may detect the
following as the objects with which your vehicle might collide,
and the pre −collision safety may operate, even though there
is no possibility of collision.
 When traveling through a curve, there is an object on the
edge of the road.
 When traveling through a curve, another vehicle is passing
from the opposite direction.
 When traveling across a narrow iron bridge.
 When there is a metallic object on the road.
 When there is a steel plate on the road at a construction site.
 When there is a bump on the road.
 When waiting to turn to the left in an intersection, and
another vehicle is passing from the opposite direction.
 If your vehicle approaches another vehicle ahead very
quickly.CAUTION
Do not rely solely on the precollision safety system
to avoid accidents. Your safe and attentive driving
practices are still the best way to avoid accidents and
you are always responsible for the operation of the
vehicle and the safety of your passengers. When
driving, always pay attention to the surrounding
conditions and the course you are driving.
 The precollision sensor’s collision detection
performance is limited. The sensor is able to detect
a forward object within 10 degrees on either left or
right side. If it is out of the range, or if there is no or
weak millimeter wave reflection, the sensor could not
detect the object and the system does not work
properly.
 Even if the precollision safety is operative in an
unavoidable collision, unless the seat belts are worn
and the brake pedal is depressed, the precollision
seat belts and precollision brake assist system will
not work.

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NOTICE
Even if there is no object with which your vehicle may
collide, the precollision safety system may be
activated as follows:
The precollision seat belts work to quickly draw
back the front seat belts by the retractors
(precollision seat belts).
 The precollision brake assist system works to apply
more powerful braking than normal braking.

DRIVING TIPS
382
BREAKIN PERIOD
Drive gently and avoid high speeds.
You need not follow a break−in schedule with your new Lexus.
But following a few simple tips for the first 1600 km (1000 miles)
can add to the future economy and long life of your vehicle:
 Avoid full throttle acceleration when starting and driving.
 Avoid racing the engine.
 Try to avoid hard stops during the first 300 km (200 miles).
 Do not drive for a long time at any single speed, either fast
or slow.
 Do not tow a trailer during the first 800 km (500 miles).
OPERATION IN FOREIGN
COUNTRIES
If you plan to drive your Lexus in another country ...
First, comply with the vehicle registration laws.
Second, confirm the availability of the correct fuel (unleaded
and minimum octane rating).
TIPS FOR DRIVING IN VARIOUS CONDITIONS
Always slow down in gusty crosswinds. This will allow you
much better control.
 Drive slowly onto curbs and, if possible, at a right angle.
Avoid driving onto high, sharp −edged objects and other
road hazards. Failure to do so can lead to severe tire
damage such as a tire burst.
Drive slowly when passing over bumps or travelling on a
bumpy road. Otherwise, the impact could cause severe
damage to the tires and/or wheels.
 When parking on a hill, turn the front wheels until they touch
the curb so that the vehicle will not roll. Apply the parking
brake, and place the transmission in “P”. If necessary, block
the wheels.
 Washing your vehicle or driving through deep water may get
the brakes wet. To see whether they are wet, check that
there is no traffic near you and then press the pedal lightly.
If you do not feel a normal braking force, the brakes are
probably wet. To dry them, drive the vehicle cautiously while
lightly pressing the brake pedal with the parking brake
applied. If they still do not work safel y, pull to the side of the
road and call a Lexus dealer for assistance.