warning light Lexus GX470 2004 Engine / LEXUS 2004 GX470 FROM SEP. 2004 PROD. (OM60B57U) Service Manual

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
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.

MAINTENANCE
535
Battery
Check the battery condition by the indicator color. See page
611 for additional information.
Brake fluid level
Make sure the brake fluid level is correct. See page 575 for
additional information.
Engine oil level
Check the level on the dipstick with the engine turned off and
the vehicle parked on a level spot. See page 561 for
additional
information.
Power steering fluid level
Check the level through the reservoir. The level should be in
the HOTº or COLDº range depending on the fluid
temperature. See page 576 for additional information.
Exhaust system
If you notice any change in the sound of the exhaust or smell
exhaust fumes, have the cause located and corrected
immediately. (See Engine exhaust cautionº on page 386.)
Vehicle interior
Items listed below should be checked regularly, e.g. while
performing periodic services, cleaning the vehicle, etc.
Lights
Make sure the headlights, stop lights, tail lights, turn signal
lights, and other lights are working. Check headlight aim. Service reminder indicators and warning buzzers
Check
that all service reminder indicators and warning buzzers
function properly.
Steering wheel
Check that it has the specified free play. Be alert for changes
in steering condition, such as hard steering, excessive free
play or strange noise.
Seats
Check that all front seat controls such as seat adjusters,
seatback recliner, etc. operate smoothly. Check that the head
restraints move up and down smoothly and that the locks hold
securely in any latched position. For folding-up second and
third seats, and detachable third seat, check that the latches
lock securely.
Seat belts
Check that the seat belt system such as buckles, retractors
and anchors operate properly and smoothly. Make sure the
belt webbing is not cut, frayed, worn or damaged.
Accelerator pedal
Check the pedal for smooth operation and uneven pedal ef fort
or catching.
Brake pedal
Check the pedal for smooth operation and the proper
clearance and free play. Check the brake booster function.

CHASSIS
600
REPLACING WHEELS
When to replace your wheels
If you have wheel damage such as bending, cracks or
heavy corrosion, the wheel should be replaced.
If you fail to replace a damaged wheel, the tire may slip off the
wheel or cause loss of handling control.
Replacement with used wheels is not recommended as they
may have been subjected to rough treatment or high mileage
and could fail without warning. Also, bent wheels which have
been straightened may have hidden structural damage and
therefore should not be used. Never use an inner tube in a
leaking wheel which is designed for a tubeless tire.
Wheel selection
When replacing wheels, care should be taken to ensure
that they are equivalent to those removed in load capacity,
diameter, rim width, and offset.
Correct replacement wheels are available at your Lexus
dealer.
A wheel of a different size or type may adversely affect
handling, wheel and bearing life, brake cooling,
speedometer/odometer calibration, stopping ability, headlight
aim, bumper height, vehicle ground clearance, and tire or snow
chain clearance to the body and chassis.
CAUTION
Observe the following instructions. Otherwise, an
accident may occur resulting in death or serious
injuries.
 Do not use wheels other than the manufacturer's
recommended size, as this may cause dangerous
handling characteristics resulting in loss of control.
 Do not use wheels of different brands, sizes and
types, as this may cause dangerous handling
characteristics resulting in loss of control.