steering wheel Lexus GS430 2006 Scheduled Maintenance Guide / LEXUS 2006 GS430/GS300 FROM JAN. 2006 PROD. (OM30786U) Service Manual

STARTING AND DRIVING
432
Variable gear ratio steering system failure
warning
G31044
If there is any malfunction in the system, the above message
appears and the master warning light comes on.
If the warning message and light come on while driving, the
system is not working. Although conventional steering
operates when maneuvered, a larger degree of wheel
maneuvering (than at the time when the system is functioning
properly) is needed when driving at low speed. At this time, the
center position of the steering wheel could be changed.
Although it is no problem to continue driving, have your vehicle
repaired at your Lexus dealer.
VEHICLE DYNAMICS
INTEGRATED MANAGEMENT (GS430 only)
Vehicle Dynamics Integrated Management (VDIM) helps
manage control for vehicle stability control system,
antilock brake system, brake assist system, traction
control system, engine output control, hillstart assist
control system and also manages variable gear ratio
steering system and electric power steering system.
In order to control sudden steering wheel operation and
the sideslip on slippery road surfaces, this system
provides excellent vehicle stability by automatically
controlling the brake, engine output and front wheel
angle.
The state of the tires will affect the performance of the vehicle
dynamics integrated management system. Be sure to check
the following:
 Are tires of specified size installed?
 Are tires of identical type installed?
 Do the tires have stipulated tire pressure?
 Are the tires worn?
A problem with the tires or modified suspension systems will
have an adverse effect on the system and may cause a
malfunction, so be careful.

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
438
BRAKE PAD WEAR LIMITINDICATORS
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.
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. A void turning the steering wheel, or stop the
vehicle. 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 581.

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
441
Display
Indicator
statusMeaningsDo this
Tire pressure
warning lightONTire inflation
pressure is
lowAdjust the tireinflation
pressure
Multi
information
displayLOW TIRE
(PRESSURE)
Tire pressure
warning lightBlinkingTire pressure
warning
system
malfunctionHave the
system
checked at
your Lexus
dealer
Multi
information
displayCHECK
(TIRE
PRES-
SURE)
SYSTEM
CAUTION
If the tire pressure warning light comes on, be sure to
observe the following precautions. Failure to do so
could cause loss of vehicle control and result in death
or serious injury.
Vehicles with runflat tires:
 Decelerate to the lowest appropriate speed as soon
as possible. Do not drive over 90 km/h (55 mph).
 Check and adjust the tire inflation pressure
immediately.
 If the tire pressure warning light comes on even after
tire inflation pressure adjustment, it is probable that
you have a flat tire. Have the tire replaced by the
nearest Lexus dealer.
 Avoid abrupt maneuvering and braking. If the vehicle
tires deteriorate, you could lose control of the
steering wheel or the brakes.
Vehicles with standard tires:
 Stop your vehicle in a safe place as soon as possible.
Adjust the tire inflation pressure immediately.
 If the tire pressure warning light comes on even after
tire inflation pressure adjustment, it is probable that
you have a flat tire. Check the tires. If the tire is flat,
change to the spare tire and have the flat tire repaired
by the nearest Lexus dealer.
 Avoid abrupt maneuvering and braking. If the vehicle
tires deteriorate, you could lose control of the
steering wheel or the brakes.

DRIVING TIPS
459
Keep ice
and snow from accumulating under the fenders.
Ice and snow built up under your fenders can make steering
difficult. During bad winter driving, stop and check under the
fenders occasionally.
Depending on where you are driving, we recommend you
carry some emergency equipment.
Some of the things you might put in the vehicle are tire chains,
window scraper, bag of sand or salt, flares, small shovel,
jumper cables, etc.
DINGHY TOWING
G32001
Your vehicle is not designed to be dinghy towed (with four
wheels on the ground) behind a motorhome.
NOTICE
Do not tow your vehicle with four wheels on the ground.
This may cause serious damage to your vehicle.

DRIVING TIPS
461

Avoid continuous speeding up and slowing down.
Stop−and−go driving wastes fuel.
 Avoid unnecessary stopping and braking. Maintain a
steady pace. Try to time the traf fic signals so you only need
to stop as little as possible or take advantage of through
streets to avoid traffic lights. Keep a proper distance from
other vehicles to avoid sudden braking. This will also
reduce wear on your brakes.
 Avoid heavy traffic or traffic jams whenever possible.
 Do not rest your foot on the brake pedal. This causes
premature wear, overheating and poor fuel economy.
 Maintain a moderate speed on highways. The faster you
drive, the greater the fuel consumption. By reducing your
speed, you will cut down on fuel consumption.
 Keep the front wheels in proper alignment. Avoid hitting
the curb and slow down on rough roads. Improper
alignment not only causes faster tire wear but also puts an
extra load on the engine, which, in turn, wastes fuel.
 Keep the bottom of your vehicle free from mud, etc.
This not only lessens weight but also helps prevent
corrosion. 
Keep your vehicle tunedup and in top shape. A dirty air
cleaner, improper valve clearance, dirty plugs, dirty oil and
grease, brakes not adjusted, etc. all lower engine
performance and contribute to poor fuel economy. For
longer life of all parts and lower operating costs, keep all
maintenance work on schedule, and if you often drive under
severe conditions, see that your vehicle receives more
frequent maintenance (For scheduled maintenance
information, please refer to the “Owner’s Manual
Supplement / Scheduled Maintenance”.)
CAUTION
Never turn off the engine to coast down hills. Your
power steering and brake booster will not function
without the engine running. Also, the emission control
system operates properly only when the engine is
running.

IN CASE OF AN EMERGENCY
475
CAUTION
If the tire pressure warning light comes on, take
your vehicle to the nearest Lexus dealer or
authorized tire dealer as soon as possible,
observing the following instructions:
Decelerate as soon as possible to the most
appropriate speed that conditions permit. Do
not drive for longer than 160 km (100 miles) or
over 90 km/h (55 mph).
 Avoid abrupt steering wheel maneuvering and
braking. If the vehicle tires deteriorate, you
could lose control of the steering wheel or the
brakes, causing death or serious injury.
 The warning system may not activate
immediately if bursts or sudden air leakage
should occur.
NOTICE
Do not use liquid sealants for a flat tire as tire
pressure warning valves and transmitters will
be damaged.
 Take due care not to go over a curb stone and
be careful of the holes in the road because
deflated tire pressure affects tire cushion
performance. The wheels, tires, body,
suspension and other components could be
damaged.
 Your ground clearance is reduced if the runflat
tire goes flat so avoid driving over obstacles
and drive slowly on rough, unpaved roads and
speed bumps. Also, do not attempt to go
through an automatic car wash as the vehicle
may get caught, resulting in damage.
 When the tires must be repaired and replaced,
have them repaired and replaced by your Lexus
dealer or an authorized tire dealer. The tire
pressure warning valves and transmitters will
be affected by the installation or removal of
tires.
 When the tires must be replaced, replace the
grommets for tire pressure warning valves and
transmitters as well.

IN CASE OF AN EMERGENCY
476
IF YOU HAVE A FLAT TIRE
(Vehicles with standard tires)
CAUTION
If the tire pressure warning light comes on,
observe the following instructions:
 Decelerate as soon as possible to the most
appropriate speed that conditions permit.
 Avoid abrupt steering wheel maneuvering and
braking. If the vehicle tires deteriorate, you
could lose control of the steering wheel or the
brakes, causing death or serious injury.
 The warning system may not activate
immediately if bursts or sudden air leakage
should occur.
1. Reduce your speed gradually, keeping a straight line.
Move cautiously off the road to a safe place − well away
from the traffic. Avoid stopping on the center divider of
a highway. Park on a level spot with firm ground.
2. Stop the engine and turn on your emergency flashers.
3. Firmly set the parking brake and put the transmission
in ”P”.
4. Have everyone get out of the vehicle on the side away
from traffic. 5. Read the following instructions thoroughly.
CAUTION
When jacking, be
sure to observe the following to
reduce the possibility of personal injury:
 Follow jacking instructions.
 Do not put any part of your body under a vehicle
supported by a jack. Otherwise, personal injury
may occur.
 Do not start or run the engine while your vehicle
is supported by the jack.
 Stop the vehicle on a level firm ground, firmly
set the parking brake and put the transmission
in ”P”. Block the wheel diagonally opposite to
the one being changed if necessary.
 Make sure to set the jack properly in the jack
point. Raising the vehicle with jack improperly
positioned will damage the vehicle or may allow
the vehicle to fall off the jack and cause
personal injury.
 Never get under the vehicle when the vehicle is
supported by the jack alone.