traction control LEXUS LS430 2005 User Guide

STARTING AND DRIVING
366
“Check VSC” warning message
31L337a
If the vehicle stability control system or the traction
control system malfunctions, the master warning light
and “TRAC OFF” indicator light come on. At this time a
warning tone sounds and the above message appears.
If the message appears, the vehicle stability control system
and traction control system do not work. Although it is no
problem to continue driving, have your vehicle checked by
your Lexus dealer as soon as possible.
BRAKE SYSTEM
The tandem master cylinder brake system is a hydraulic
system with two separate sub −systems. If either sub −system
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 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.

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.

IN CASE OF AN EMERGENCY
415
CAUTION
Before driving, make sure all the tools, jack and
flat tire are securely in place in their storage
location to reduce the possibility of personal
injury during a collision or sudden braking.
 When reinstalling a standard tire, take due care
in handling the ornament to avoid unexpected
personal injury.
IF YOUR VEHICLE BECOMES STUCK
If your vehicle becomes stuck in snow, mud, sand, etc.,
then you may attempt to rock the vehicle free by moving
it forward and backward.
Turn off the traction control system to become unstuck to
allow the tires to spin enough to remove the vehicle from
the obstruction. (For details, see “Vehic le stability control
system” on page 364.)
CAUTION
Do not attempt to rock the vehicle free by moving it
forward and backward if people or objects are anywhere
near the vehicle. During the rocking operation the
vehicle may suddenly move forward or backward as it
becomes unstuck, causing injury or damage to nearby
people or objects.

CHASSIS
475
Uniform tire quality grading
This information has been prepared in accordance
with regulations issued by the National Highway
Traffic Safety Administration of the U.S. Department
of Transportation. It provides the purchasers and/or
prospective purchasers of Lexus vehicles with
information on uniform tire quality grading.
Your Lexus dealer will help answer any questions
you may have as you read this information.
DOT quality grades All passenger vehicle tires
must conform to Federal Safety Requirements in
addition to these grades. Quality grades can be
found where applicable on the tire sidewall between
tread shoulder and maximum section width. For
example: Treadwear 200 Traction AA Temperature
A
Treadwear − The treadwear grade is a comparative
rating based on the wear rate of the tire when tested
under controlled conditions on a specified government
test course. For example, a tire graded 150 would wear
one and a half (1 − 1/2) times as well on the government
course as a tire graded 100. The relative performance
of tires depends upon the actual conditions of their use,
however, and may depart significantly from the norm
due to variations in driving habits, service practices and
differences in road characteristics and climate. Traction
AA, A, B, C − The traction grades, from highest
to lowest, are AA, A, B and C, and they represent the
tire’s ability to stop on wet pavement as measured under
controlled conditions on specified government test
surfaces of asphalt and concrete. A tire marked C may
have poor traction performance.
Warning: The traction grade assigned to this tire is
based on braking (straight ahead) traction tests and
does not include cornering (turning) traction.
Temperature A, B, C − The temperature grades are A
(the highest), B, and C, representing the tire’ s resistance
to the generation of heat and its ability to dissipate heat
when tested under controlled conditions on a specified
indoor laboratory test wheel. Sustained high
temperature can cause the material of the tire to
degenerate and reduce tire life, and excessive
temperature can lead to sudden tire failure. The grade
C corresponds to a level of performance which all
passenger car tires must meet under the Federal Motor
Vehicle Safety Standard No. 109. Grades B and A
represent higher levels of performance on the laboratory
test wheel than the minimum required by law.
Warning: The temperature grades for this tire are
established for a tire that is properly inflated and not
overloaded. Excessive speed, underinflation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.

CHASSIS
479
TYPES OF TIRES
Determine what kind of tires your vehicle is originally
equipped with.
1. All season tires
All season tires are designed to provide better traction
in snow and to be adequate for driving in most winter
conditions, as well as for use all year round.
All season tires, however, do not have adequate traction
performance compared with snow tires in heavy or loose
snow. Also, all season tires fall short in acceleration and
handling performance compared with summer tires in
highway driving.
2. Summer tires
Summer tires are high −speed capability tires best suited
to highway driving under dry conditions.
Since summer tires do not have the same traction
performance as snow tires, summer tires are
inadequate for driving on snow −covered or icy roads.
For driving on snow −covered or icy roads, we
recommend using snow tires. If installing snow tires, be
sure to replace all four tires.
CAUTION
 Do not mix all season and summer tires on your
vehicle as this can cause dangerous handling
characteristics, resulting in loss of control.
 Do not use tires other than the manufacturer’s
designated tires, and never mix tires or wheels
of the sizes different from the originals, as this
could result in loss of control and could cause
death or serious injury.

CHASSIS
483
INSTALLING SNOW TIRES ANDCHAINS
When to use snow tires or chains
Snow tires or chains are recommended when driving on
snow or ice.
On wet or dry roads, conventional or radial tires provide better
traction than snow or studded tires.
Snow tire selection
If you need snow tires, select tires of the same size,
construction and load capacity as the originally installed
tires.
Do not use tires other than stated above. Since your vehicle
has radial tires as original equipment, make sure your snow
tires also have radial construction. Do not install studded tires
without first checking local regulations for possible restrictions.
CAUTION
Observe the following instruction. Otherwise, an
accident may occur resulting in death or serious
injuries.
Do not use snow tires other than the manufacturer’s
recommended size, as this may cause dangerous
handling characteristics resulting in loss of control.
Snow tire installation
Snow tires should be installed on all wheels.
Installing snow tires on the rear wheels only can lead to an
excessive difference in road grip capability between the front
and rear tires which could cause loss of vehicle control.
CAUTION
Do not drive with the snow tires incorrectly inflated.
 Never drive over 120 km/h (75 mph) with any type of
snow tires.
Tire chain selection
Regulations regarding the use of tire chains vary
according to location or type of road. Always check local
regulations before installing chains.
Use SAE Class “S” type radial tire chains, with the exception
of radial cable chains or V− bar type chains.