2006 Lexus GS430 engine overheat

STARTING AND DRIVING
424
Hillstart assist control system failure
warning
G31039
 1GS430 2GS300
If the hillstart assist control system malfunctions, the
slip indicator light (twowheel drive models only) and
brake system warning light (yellow) come on. At this time,
the above message appears. (GS430 only—In some
cases, the multiinformation display shows either
“CHECK VSC” or “CHECK ECB” only.)
If the message appears, the hill−start assist control system,
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.
VARIABLE GEAR RATIO STEERING SYSTEM (GS430 only)
The variable gear ratio steering system adjusts the wheel
turning angle depending on the vehicle speed and how
much you turn the steering wheel.
The vehicle wheel turning angle will be changed with a smaller
degree of wheel maneuvering when you are driving at very low
speed such as when putting your vehicle into a garage.
When you start or stop the engine, you may hear a small noise
and the steering wheel may move slightly. This is caused when
the system starts or stops, and does not indicate a malfunction.
In the following cases, to prevent the system from overheating,
the system could be temporarily deactivated with the change
in the center position of the steering wheel. This is not a
malfunction. After the cause of the problem is eliminated, the
system will return to normal automatically after a few minutes.
 If you continue maneuvering the steering wheel when the
vehicle is stopped or running at very low speed
 If you continue driving holding the steering wheel to the
extreme right or left
 If you maneuver the steering wheel immediately after
starting the engine at less than about −30C (− 22F)

STARTING AND DRIVING
432
ELECTRIC POWER STEERINGSYSTEM
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 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.

DRIVING TIPS
451
CAUTION
Before driving off, make sure the parking brake is
fully released and that the parking brake reminder
light is off.
 Do not leave your vehicle unattended while the
engine is running.
 Do not rest your foot on the brake pedal while driving.
It can cause dangerous overheating, needless wear,
and poor fuel economy.
 To drive down a long or steep hill, reduce your speed
and downshift. Remember, if you ride the brakes
excessively, they may overheat and not work
properly. See page 359.
 Be careful when accelerating, upshifting,
downshifting or braking on a slippery surface. The
abrupt change in engine speed, such as sudden
acceleration or engine braking, could cause the
vehicle to skid or spin.
 Even if the legal speed limit permits it, do not drive
over 140 km/h (85 mph) unless your vehicle has
highspeed capability tires. Driving over 140 km/h
(85 mph) may result in tire failure, loss of control and
possible injury. Be sure to consult a tire dealer to
determine whether the tires on your vehicle are
highspeed capability tires or not before driving at
such speeds.
Do not continue normal driving when the brakes are
wet. If they are wet, your vehicle will require a longer
stopping distance, and it may pull to one side when
the brakes are applied. Also, the parking brake will
not hold the vehicle securely.

DRIVING TIPS
455

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.

SECTION 4
461
IN CASE OF AN EMERGENCY
In case of an emergency
If your engine stalls while driving462
. . . . . . . . . . . . . . . . . . . . . . . . . . .
If your vehicle will not start 462
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If you cannot increase engine speed 466
. . . . . . . . . . . . . . . . . . . . . . . .
If your vehicle overheats 467
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If you have a flat tire (vehicles with run −flat tires) 468
. . . . . . . . . . . . .
If you have a flat tire (vehicles with standard tires) 469
. . . . . . . . . . . .
If your vehicle becomes stuck 481
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If your vehicle needs to be towed 482
. . . . . . . . . . . . . . . . . . . . . . . . . .
If you cannot shift automatic transmission
selector lever 489
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . .
If you lose your keys or lock yourself out 490
. . . . . . . . . . . . . . . . . . . .

IN CASE OF AN EMERGENCY
463
NOTICE
Do not pull or pushstart the vehicle. It may damage
the vehicle or cause a collision when the engine starts.
Also the threeway catalytic converter may overheat
and become a fire hazard.
If the engine turns over at its normal speed but will not
start
1. The engine may be flooded because of repeated cranking.
See ”(b) Starting a flooded engine” for further instructions.
2. If the engine still will not start, it needs adjustment or repair.
Call a Lexus dealer, Roadside Assistance or Customer
Service Assistance. (See ”Foreword”.)
(b) Starting a flooded engine
If the engine will not start, your engine may be flooded
because of repeated cranking.
If this happens, push the engine switch while the brake pedal
is depressed with your left foot and the accelerator pedal is
depressed with your right foot. Then the cranking hold function
stops automatically, and you can try starting the engine with
your foot off the accelerator pedal.
If the engine does not start, wait a few minutes and try again.
If the engine still will not start, it needs adjustment or repair.
Call a Lexus dealer, Roadside Assistance or Customer
Service Assistance. (See ”Foreword”.)
(c) Jump starting
To avoid serious personal injury and damage to your
vehicle which might result from battery explosion, acid
burns, electrical burns, or damaged electronic
components, these instructions must be followed
precisely.
If you are unsure about how to follow this procedure, we
strongly recommend that you seek help from your Lexus
dealer, Roadside Assistance or Customer Service Assistance.
(See ”Foreword”.)
CAUTION
 Batteries contain sulfuric acid which is poisonous
and corrosive. Wear protective safety glasses when
jump starting, and avoid spilling acid on your skin,
clothing, or vehicle.
 If you should accidentally get acid on yourself or in
your eyes, remove any contaminated clothing and
flush the affected area with water immediately. Then
get immediate medical attention. If possible,
continue to apply water with a sponge or cloth while
en route to the medical office.
 The gas normally produced by a battery will explode
if a flame or spark is brought near. Use only
standardized jumper cables and do not smoke or
light a match while jump starting.

IN CASE OF AN EMERGENCY
467
IF YOUR VEHICLE OVERHEATS
If your engine coolant temperature gauge indicates
overheating, if you experience a loss of power, or if you
hear a loud knocking or pinging noise, the engine has
probably overheated.
When the engine overheats
Pull safely off the road, stop the vehicle and turn on your
emergency flashers. Put the transmission in ”P” and apply the
parking brake.
A: If steam is coming from your engine:
Turn off the engine. Leave the hood closed until there is no sign
of steam or coolant. Your engine could have been seriously
damaged already. Call your Lexus dealer for assistance.
CAUTION
To help avoid personal injury, keep the hood closed until
there is no steam. Escaping steam or coolant is sign of
very high pressure.
B: If no steam is coming from your engine:
Leave the engine running and turn off the air conditioning.
Check the following.
 Is the cooling fan operating?
 Is the coolant in the acceptable range?
 Is the engine drive belt O.K.?
CAUTION
When the engine is running, keep hands and clothing
away from the moving fan and engine drive belt.
 Do not attempt to remove the radiator cap when the
engine and radiator are hot. Serious injury could
result from scalding hot fluid and steam blown out
under pressure.
If the cooling fan is not operating or the coolant is not in the
acceptable range, turn off the engine and call your Lexus
dealer.
If both conditions are O.K., after the engine coolant
temperature has cooled to normal, continue driving your
vehicle.
If the engine coolant temperature does not cool down, or your
vehicle overheats again, have it checked as soon as possible
by your Lexus dealer.