2005 LEXUS LS430 brakes

GAUGES, METERS AND SERVICE REMINDER INDICATORS
84
(a) Brake System Warning Light
This light comes on in the following cases when the ignition
switch is in the “ON” position.
When the parking brake is applied ...
This light comes on for a few seconds when the ignition switch
is turned to the “ON” position even after the parking brake is
released.
 When the brake fluid level is low ...
CAUTION
It is dangerous to continue driving normally when the
brake fluid level is low.
Have your vehicle checked at your Lexus dealer in the
following case:
The light does not come on even if the parking brake is
applied when the ignition switch is in the “ON” position.
 The light does not come on even if the ignition switch is
turned on with the parking brake released.
A warning light turning on briefly during operation does not
indicate a problem.
CAUTION
If either of the following conditions occurs, immediately
stop your vehicle at a safe place and contact your Lexus
dealer.
 The light does not turn off even after the parking
brake is released while the engine is running.
In this case, the brakes may not work properly and
your stopping distance will become longer. Depress
the brake pedal firmly and bring the vehicle to an
immediate stop.
 The brake system warning light remains on together
with the “ABS” warning light.
In this case, not only the antilock brake system will
fail but also the vehicle will become extremely
unstable during braking.

STARTING AND DRIVING
334If no vehicle is running ahead of you:
1
Cruising at a fixed speed: If there is no vehicle detected
ahead, your cruising speed is maintained at the preset
speed from about 45 km/h (28 mph) to about 135 km/h (85
mph). The preset speed is displayed in the
multi−information display. For the vehicle speed setting,
see “Setting operation ” on page 340.
If a vehicle is detected ahead of you:
2 Deceleration cruising function: If a slower moving
vehicle is detected ahead of you, your vehicle cruising
speed decreases within the range of about 40 km/h (25
mph) to about 135 km/h (85 mph). The multi− information
display shows the preset speed, the detected vehicle
ahead and selected vehicle− to−vehicle distance. If your
vehicle gets closer to the vehicle ahead because of
insufficient automatic deceleration, then the warning tone
warns you to also manually apply brakes.
3 Followup cruising function: After deceleration, your
vehicle cruising speed changes in proportion to the speed
of the vehicle ahead to maintain an appropriate distance
from your vehicle to the vehicle ahead. The
vehicle −to−vehicle distance can be changed. For details,
see “Changing vehicle −to−vehicle distance setting” on
page 346.
4 Acceleration cruising function: If the vehicle ahead
changes lanes, your vehicle cruising speed will be
gradually increased up to the preset speed, and your
vehicle resumes fixed −speed cruising.
CAUTION
Under certain conditions where the vehicle in front
slows drastically, or is stopped, the dynamic radar/laser
cruise control will neither warn you nor decelerate. The
driver must depress the brake pedal to slow down,
ensuring collision avoidance or that sufficient
vehicletovehicle distance is maintained.
When vehicle −to−vehicle distance control mode is activated,
you must still be attentive to road and traf fic conditions. Should
your vehicle speed decrease below about 40 km/h (25 mph),
the dynamic radar/laser cruise control will shut off, requiring
you to apply the brakes to slow. When a vehicle ahead slows
suddenly, stops or a vehicle cuts in front, the system may slow
your vehicle abruptly, but the automatic braking will cease if the
speed decreases below about 40 km/h (25 mph) requiring the
driver’s manual application of brakes.

STARTING AND DRIVING
342In the following case, the preset speed automatically
cancels out. At this time, the multiinformation display
shows “RADAR READY” and the dynamic radar/laser
cruise control enters the ready mode.
The vehicle speed falls below about 40 km/h (25 mph). (40
km/h (25 mph) is designated as a cancel speed.)
CAUTION
In this case, the warning tone reminds you that the
dynamic
radar/laser cruise control is cancelled and you
must apply the brakes to slow the vehicle.
In the following cases, the warning messages appear and
the preset speed automatically cancels out. When
dynamic radar/laser cruise control is restored, the
warning messages turn off and dynamic radar/laser
cruise control enters “RADAR READY” mode.
a. The slip indicator light blinks and a warning tone sounds.
(This occurs when the vehicle is about to skid.)
b. The driving pattern selector switch is set to “SNOW” mode.
c. The anti −lock brake system is activated by automatic
braking. (The warning tone sounds.)
d. The sensor does not operate properly because a foreign
matter sticks to the sensor.
Dynamic radar cruise control—
e. The wipers are operated at high speed (including high
speed operation with the wiper lever in the “AUTO” position.)
Dynamic laser cruise control—
f. The wipers are operated at high or low speeds (including
high and low speed operations with the wiper lever in the
“AUTO” position.)

STARTING AND DRIVING
362
TRACTION CONTROL SYSTEM
The traction control system automatically helps prevent
the spinning of rear wheels when the vehicle is started or
accelerated on slippery road surfaces.
When the ignition switch is turned to “ON”, the system
automatically turns on.
CAUTION
Under certain slippery road conditions, full traction of
the vehicle and power against rear wheels cannot be
maintained, even though the traction control system is
in operation. Do not drive the vehicle under any speed
or maneuvering conditions which may cause the
vehicle to lose traction control. In situations where the
road surface is covered with ice or snow, your vehicle
should be fitted with snow tires or tire chains. Always
drive at an appropriate and cautious speed for the
present road conditions.
31L138a
 Slip indicator light
Leave the system on during the ordinary driving so that it
can operate when needed.
You may hear a sound in the engine compartment for a few
seconds just after the vehicle begins to move. This means that
the traction control system is in the self −check mode, but does
not indicate a malfunction.
When the traction control system is operating, the following
conditions occur:
 The system controls the spinning of the rear wheels. At this
time, the slip indicator light blinks.
 You may feel vibration or noise in your vehicle, caused by
operation of the brakes. This indicates the system is
functioning properly.
The slip indicator light comes on for a few seconds when the
ignition switch is turned to “ON”. If the indicator light does not
come on when the ignition is turned on, contact your Lexus
dealer.

STARTING AND DRIVING
364
“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.
VEHICLE STABILITY CONTROLSYSTEM
The vehicle stability control system helps provide
comprehensive control of the systems such as antilock
brake system, traction control, engine control, etc. This
system automatically controls the brakes and engine to
help prevent the vehicle from skidding when cornering on
a slippery road surface or operating steering wheel
abruptly.
This system activates when the vehicle speed is about more
than 15 km/h (9 mph).
You may hear a sound in the engine compartment for a few
seconds just after the vehicle begins to move. This means that
the system is in the self −check mode, but does not indicate a
malfunction.

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
369
If any 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 switch is
turned to the “ON” 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 “ABS” 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 antilock brake system will fail
but also the vehicle will become extremely unstable
during braking.
Drumindisc 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.
Brake assist system
If you slam the brakes on such as in an emergency or
apply the brakes more firmly than usual such as when
descending the hill with the designated number of
occupants in the vehicle, the brake assist system
provides more powerful braking.
If you slam the brakes on or apply the brakes more firmly, 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).
For an explanation of this system’s warning light, see “ABS”
warning light on page 87 or 368.

STARTING AND DRIVING
371

The degree of the tread wear is very different among the
installed tires.
 Rapid acceleration/deceleration or sharp turns are
continued.
 Towing a trailer.
 The loading is over the limit or unbalanced.
 Initialization was not performed correctly after replacing or
rotating tires or wheels.
 The outside temperature is below 0 C (32F) or above
40 C (104 F).
If the warning message appears again on the
multi−information display after adjusting tire inflation pressure,
the system may be malfunctioning. Have your vehicle
checked by your Lexus dealer as soon as possible.
CAUTION
When the tire pressure warning message appears,
observe the following instructions:
 Adjust the tire inflation pressure to the specified level
as soon as possible.
 Avoid abrupt steering wheel maneuvering and
braking. If the vehicle tires are deteriorated, you
could lose control of the steering wheel or the brakes,
causing death or serious injury.
Note: The tire pressure mon itoring system on your
vehicle will warn you when one of your tires is
significantly underinflated and when some
combinations of your tires are significantly
underinflated. However, there are other combinations
of significantly underinflated tires for which your tire
pressure warning system may not warn you. These
other combinations are relatively common, accounting
for approximately half the instances in which vehicles
have significantly underinflated tires. For example,
your system may not warn you when both tires on the
same side or on the same axle of your vehicle are
significantly underinflated. It is particularly important,
therefore, for you to check the tire inflation pressure in
all of your tires regularly and maintain proper pressure.