2004 Lexus GX470 Audio System / LEXUS 2004 GX470 FROM SEP. 2004 PROD. OWNER'S MANUAL (OM60B57U)

STARTING AND DRIVING
430You 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, and it is not a malfunction.
CAUTION

Do not pump the brake pedal if the engine stalls.
Each push on the pedal uses up your brake fluid
pressure reserve.
 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.
Anti-lock brake system
The anti-lock brake system is designed to automatically
help prevent lock-up of the wheels during a sudden brake
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 br ake 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 anti-lock 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 to the forward.

STARTING AND DRIVING
431
CAUTION
Do not overestimate the anti-lock brake system:
Although the anti-lock 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 anti-lock
brake system on.
If tire grip performance exceeds its capability, or if
hydroplaning occurs during high speed driving in the
rain, the anti-lock brake system does not provide
vehicle control.
Anti-lock 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 anti-lock
brake system, your vehicle may require a longer
stopping distance in the following cases:
 Driving on rough, gravel or snow-covered 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 anti-lock brake system detects vehicle
speeds using the s peed 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.

STARTING AND DRIVING
432ABSº warning light

1U.S.A.2Canada
The light comes on when the ignition key is turned to the ONº
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 ABSº warning light is on (and the brake system
warning light is off), the anti-lock brake system, the brake
assist system, the active traction control system and the
vehicle stability control system do/does not operate, but the
brake system still operates conventionally.
When the ABSº 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.
If either 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 key is turned
to the ONº 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 ABSº 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 anti-lock brake system will fail
but also the vehicle will become extremely unstable
during braking.
Either of the following conditions may occur, but do not
indicate a malfunction:
 The light may stay on for about 60 seconds after the ignition
key is turned to the ONº position. 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.

STARTING AND DRIVING
433
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 lightº on page 67.
Drum-in-disc 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.
TIRE PRESSURE WARNING SYSTEM
The tire pressure warning system is designed to provide
warning when tire inflation pressure of one or more of
your tires (including the spare tire) is low. The low tire
pressure warning light comes on to inform you that low
tire inflation pressure may hamper driving.

Low tire pressure warning light
This light comes on when the ignition key is turned to the ONº
position. It goes off after a few seconds. This indicates that the
tire pressure warning system is functioning properly.

STARTING AND DRIVING
434If the low tire pressure warning light comes on or blinks,
do the following.
If the warning light comes on:
Stop your vehicle in a safe place as soon as possible and
check that the inflation pressure of all tires (including the
spare tire) is as specified on the tire and loading
information
label. (See Checking tire inflation pressureº
on page 578.) If the warning light comes on even after tire
inflation pressure adjustment, you may have a flat tire. If
you have a flat tire, replace it with the spare tire. For
details, see If you have a flat tireº on page 486.
The warning light goes off a few minutes after air is put into the
deflated tire.
This warning light may turn on due to natural causes such as
natural air leaks or tire pressure changes caused by
temperature. In this case, adjusting the tire pressure will turn
off the warning light.
CAUTION
When the low tire pressure warning light comes on,
observe the following instructions:
 Depending on the conditions, reduce to an
appropriate speed as soon as possible.
 Adjust the tire pressure to the specified level as soon
as possible.
 Avoid abrupt steering wheel maneuvering and
braking. Tire deterioration may reduce steering
wheel control and brake effectiveness. This may lead
to serious injury or death.
 The tire pressure warning system may not activate
immediately if sudden bursts of air leakage occur.

STARTING AND DRIVING
435
NOTICE
Do not use liquid sealants for a flat tire as air pressuresensors will be damaged.
When the tires must be repaired or replaced, havethem repaired or replaced by the nearest Lexusdealer or authorized tire dealer. The tire pressuresensors will be affected by the installation or removal
of tires.
The tire pressure warning system is not to be used as a substitute for regular inspections. Be sure to check
the air pressure in the tires on a regular basis.
When the tires must be replaced, replace the grommets for air pressure sensors as well.
If the warning light blinks:
The tire pressure warning system may be malfunctioning.
Contact your Lexus dealer.System malfunction
The tire pressure warning system does not function
properly under certain circumstances. In the following
cases, the low tire pressure warning light may not come
on even if the tire inflation pressure is low, or it may come
on when the tire inflation pressure is actually normal.
 Electric devices or facilities using similar radio wave
frequencies are nearby.
 A radio set to similar frequencies is in use.
 A lot of snow or ice covers the vehicle, in particular, around
the wheels or wheel housings.
 The tires are not equipped with an air pressure sensor.
 Tire chains are used.

STARTING AND DRIVING
436
Non-genuine Lexus wheels are used.
 Although the tires are equipped with air pressure sensors,
the selector switch (see page 442.) is set to other tire setting.
CAUTION
The use of non-genuine wheels will cause the air
pressure sensors to transmit the electronic code in
different manner, resulting in the system failure.
 The use of different type of tires with genuine wheels
may also cause the malfunction of the system.

STARTING AND DRIVING
437
CAUTION
When the tire pressure monitoring system warning light
is lit, one or more of your tires is significantly
under-inflated. You should stop and check your tires as
soon as possible, and inflate them to the proper
pressure as indicated on the vehicle's tire information
placard. Driving on a significantly under-inflated tire
causes the tire to overheat and can lead to tire failure.
Under-inflation also reduces fuel efficiency and tire
tread life, and may affect the vehicle's handling and
stopping ability. Each tire, including the spare, should
be checked monthly when cold and set to the
recommended inflation pressure as specified in the
vehicle placard and owner's manual.
For vehicles sold in U.S.A.