wheel Lexus GX470 2005 Scheduled Maintenance Guide / LEXUS 2005 GX470 (OM60B11U) Service Manual

STARTING AND DRIVING
413
The indicator light tells when the differential lock is engaged.
Note that the differential is not still locked as long as the
indicator light remains off.
When
the operation is not completed, the indicator blinks. If the
indicator light does not go off when you push out the center
differential lock switch, drive straight ahead while accelerating
or decelerating, or drive in reverse.
The center differential lock system operation is not completed
within 5 seconds while the cruise control system is set, cancel
the cruise control system. To cancel the cruise control system,
see ªCruise controlº on page 419. If the indicator light does not go off when you push out the
center differential lock switch, drive straight ahead while
accelerating or decelerating, or drive in reverse.
See ª(b) Shifting procedureº for further instructions.
(b) Shifting procedure
To shift between unlock and lock modes in ªHº, push the
center differential lock switch.
To shift between unlock and lock modes in ªLº,
push the
center differential lock switch.
To shift between ªHº and ªLº, stop the vehicle, put the
transmission into ªNº and move the four±wheel drive control
lever.
CAUTION
Never move the four±wheel drive control lever if wheels
are slipping. Stop the slipping or spinning before
shifting.

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414
NOTICE
For normal driving on dry and hard surface roads,unlock the center differential. To prevent damage to thecenter differential lock system, do not push the centerdifferential lock switch when the vehicle is cornering or
when its wheels are spinning freely off the ground. If the
indicator light does not go off when unlocking the center differential, drive straight ahead while
accelerating or decelerating, or drive in reverse.

STARTING AND DRIVING
430We recommend you to select the mode

2
for ordinary
driving. The damping effect will be changed automatically to
provide good riding comfort.
When your vehicle is loaded heavily or you are driving in an
unpaved road, the mode
3
or 4
will be recommended. To
provide good vehicle stability, the damping effect will be harder
than for ordinary driving mode.
With the four±wheel drive control lever at ªLº, the damping
effect suitable for off±road driving will be provided in any mode.
ACTIVE TRACTION CONTROL
SYSTEM
The active traction control system automatically helps
prevent the spinning of 4 wheels when the vehicle is
started or accelerated on slippery road surfaces.
When the ignition key is turned to ªONº, the system
automatically turns on.
CAUTION
Under certain slippery road conditions, full traction of
the vehicle and power to the 4 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.

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431

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 when the engine is started or just after the vehicle
begins to move. This means that the active traction control
system is in the self±check mode, but does not indicate a
malfunction.
When the active traction control system is operating, the
following conditions occur:
 The system controls the spinning of the 4 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 key is turned to ªONº. If the indicator light does not
come on when the ignition is turned on, contact your Lexus
dealer.
The brake actuator temperature increase during continuous
operation of the following systems.

Active traction control system
 Vehicle stability control system
 Downhill assist control system
 Hill±start assist control
If the brake actuator temperature becomes too high while any
of the systems is operating, a buzzer will start to sound
intermittently to indicate that the active traction control system
can no longer operate. In this case, immediately stop your
vehicle at a safe place.
If the system continues to operate, the buzzer sound changes
from intermittent to continuous. (The continuous buzzer
sounds for about 3 seconds.) At the time, the slip indicator light
will come on and the active traction control system temporarily
stops operating in order to protect the brake actuator.
(Although the active traction control system does not operate,
there is no problem to continue your driving.) The system will
be automatically restored after a short time and the slip
indicator light goes out.

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433
VEHICLE STABILITY CONTROLSYSTEM
The vehicle stability control system helps provide
integrated control of the systems such as anti±lock brake
system, traction control, engine control, etc. This system
automatically controls the output of the brakes or 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 about more than
15 km/h (9mph).
You may hear a 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 system is in the
self±check mode, but does not indicate a malfunction.
CAUTION
 Do not rely excessively on the vehicle stability
control system. Even if the vehicle stability control
system is operating, you must always drive carefully
and attentively to avoid serious injury. Reckless
driving will result in an unexpected accident. If the
slip indicator light blinks and an alarm sounds,
special care should be taken while driving.
Only use tires of specified size. The size,
manufacturer, brand and tread pattern for all 4 tires
should be the same. If you use the tires other than
specified, or different type or size, the vehicle
stability control system may not function correctly.
When replacing the tires or wheels, contact your
Lexus dealer.
 In situations where the road surface is covered with
ice or snow, your vehicle should be fitted with snow
tires or tire chains.

Slip indicator light
If the vehicle is going to skid during driving, the slip indicator
light blinks and an alarm sounds intermittently. Special care
should be taken while driving.

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436
The warning light comes on while driving.
DOWNHILL ASSIST CONTROL
SYSTEM
The downhill assist control system is a system that
assists the deceleration of the engine brake when you
drive down a steep hill. When you are driving down a hill
with the four±wheel drive control lever in the ªLº position,
push the ªDACº switch to limit the vehicle's acceleration.
If the vehicle is traveling at a speed of 25 km/h (15 mph) or
less, you can descend at a constant speed.
CAUTION
Do not rely excessively on the downhill assist control
system. It may not be able to maintain a low speed over
road surf aces or off±road surfaces on which sliding can
easily occur, such as extremely steep slopes or icy or
muddy roads.
Turning on the system
1. Shift the four±wheel drive control lever to the ªLº
position.
The system will not operate if the four±wheel drive control lever
is in the ªHº position.
2. In order to make full use of the engine brake, putting the
transmission in ªLº or ª2º is recommended.
The system will operate even if the transmission selector lever
is in ªDº, ª4º, ª3º or ªNº. However, when it is in ªLº or ª2º the
engine brake can also be utilized enabling the system to
operate more effectively.
3. Push the ªDACº switch to turn the system on. The
downhill assist control system indicator light on the
instrument panel will come on.

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437
If the downhill assist control system indicator light flashes, the
transmission selector lever may be in ªNº or four±wheel drive
control lever may be in the ªHº position.
If the indicator light does not come on when the switch is
pushed, contact your Lexus dealer.

Slip indicator light
With the vehicle traveling at a speed of 25 km/h (15 mph) or
less, release your foot from the accelerator or brake pedal to
activate the system. The vehicle will descend the hill at a low
speed. While the system is operating, the slip indicator light on
the instrument panel will flash and the stop lights and high
mounted stoplight will be lit.
If you push the ªDACº switch to turn the system off while it is
in operation, the system will stop operating gradually. The
downhill assist control system indicator light will flash to alert
the driver. To continue driving at a low speed, push the ªDACº
switch to turn the system on.
The slip indicator light and downhill assist control system
indicator l
ight come on for a few seconds when the ignition key
is turned to ªONº. If any of the indicator lights does not come
on when the ignition is turned on, contact your Lexus dealer.
The brake actuator temperature increases during continuous
operation of the following systems.
 Active traction control system
 Vehicle stability control system
 Downhill assist control system
 Hill±start assist control
If the brake actuator temperature becomes too high while any
of the systems is operating, a buzzer will start to sound
intermittently to indicate that the downhill assist control system
can no longer operate. In this case, stop your vehicle
immediately at a safe place.
If the system continues to operate, the buzzer sound changes
from intermittent to continuous. (The continuous buzzer
sounds for about 3 seconds.) At this time, the slip indicator light
will come on and the downhill assist control system stops
operating temporarily in order to protect the brake actuator.
(Although the downhill assist control system does not operate,
it is no problem to continue your driving.) The system will be
automatically restored after a short time and the slip indicator
light goes out.

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442
BRAKE SYSTEM
This brake system has 2 independent hydraulic circuits. If
either circuit 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 brake fluid pressurized by the pump
to power±assist the brakes. If the brake booster fails during
driving, the brake system warning light comes on and buzzer
sounds continuously. In this case, the brakes may not work
properly. If they do not work well, depress the brake pedal
firmly. If the brake system warning light comes on, immediately
stop your vehicle and contact your Lexus dealer.
The brake system warning light may stay on for about 60
seconds after the ignition key is turned to the ªONº position. It
is normal if the light turns off after a while.
Depressing the brake pedal repeatedly may turn on the brake
system warning light and buzzer. It is normal if the light goes
out and the buzzer stops sounding 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, 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 pr event 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.

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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.
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.

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444
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 speed 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.ªABSº warning light

1U.S.A.2Canada
The light comes on when the ignition key is turned to the ªONº
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 ªABSº 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 ªABSº 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.