engine Lexus GX470 2006 Engine / LEXUS 2006 GX470 (OM60B99U) Repair Manual

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356
FOURWHEEL DRIVE SYSTEM
(a) Fourwheel drive control
Use the fourwheel drive control lever and center
differential lock switch to select the following transfer and
center differential modes.
The “H” and “L” position of the four −wheel drive control lever
provides either lock or unlock mode of the center differential
depending on the center differential lock switch position.
Use the center dif ferential lock system if your wheels get stuck
in a ditch, or when you are driving on a slippery or bumpy
surface. When the center differential is locked, the vehicle
stability control system is automatically turned off and the
center dif ferential lock and “VSC OFF” indicator lights come on
because the function that controls engine performance
interferes with the process of freeing your wheels.
NOTICE
As soon as the center differential lock switch is turned
on, the “VSC OFF” indicator light comes on. After the
wheels are out of the ditch or off the slippery or bumpy
surface, turn the center differential lock switch off.
Make sure the center differential lock indicator light and
vehicle stability control system off indicator light turn
off.
“H” (high speed position, center differential unlocked):
Lever at “H”, center differential lock switch left out
Use this for normal driving on all types of roads, from dry
hard−surfaced roads to wet, icy or snow −covered roads. This
position gives greater economy, quietest ride, least wear and
better vehicle control.
“H” (high speed position, center differential locked): Lever
at “H”, center differential lock switch pushed in
Use this for greater traction when you experience a loss of
power, such as wheel slipping, in the center differential unlock
mode.
“N” (neutral position): Lever at “N”
No power is delivered to the wheels. The vehicle must be
stopped.

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Check surroundings for safety.
If a bright light (for example, sunlight reflected off the vehicle
body) is picked up by the camera, the smear effect* peculiar to
the camera may occur.
*: Smear effect — A phenomenon that occurs when a bright
light (for example, sunlight reflected off the vehicle body) is
picked up by the camera; when transmitted by the camera, the
light source appears to have a vertical streak above and below
it.
CRUISE CONTROL
The cruise control is designed to maintain a set cruising
speed without requiring the driver to operate the
accelerator. Cruising speed can be set to any speed above
40 km/h (25 mph).
Within the limits of the engine’s capabilities, cruising speed can
be maintained up or down grades. However, changes in
vehicle speed may occur on steeper grades.
CAUTION
 To help maintain maximum control of your vehicle,
do not use the cruise control when driving in heavy
or varying traffic, or on slippery (rainy, icy or
snowcovered) or winding roads.
 Avoid vehicle speed increases when driving
downhill. If the vehicle speed is too fast in relation to
the cruise control set speed, cancel the cruise
control then downshift the transmission to use
engine braking to slow down.

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5Resetting to a slower speed
Push the control lever downward in the “ − SET” direction and
hold it. Release the lever when the desired speed is attained.
While the lever is held downward, the vehicle speed will
gradually decrease.
When the difference between the actual vehicle speed and the
set speed is less than 5 km/h (3 mph), the set speed can be
lowered 1.6 km/h (1 mph) each time by pushing the control
lever downward in the “ − SET” direction quickly.
However, a quicker way to reset is to depress the brake pedal
and then push the control lever downward in the “ − SET”
direction.
Even if you downshift the transmission from the “D” position to
“4” position with the cruise control on, engine braking will not
be applied because the cruise control is not cancelled. To
decrease the vehicle speed, reset to a slower speed with the
cruise control lever or depress the brake pedal. If you use the
brake pedal, cruise control is cancelled.Cruise control failure warning
If the “CRUISE” indicator light flashes when using the cruise
control, press the “ON− OFF” button to turn the system off and
then press it again to turn it on.
If any of the following conditions then occurs, there is some
trouble in the cruise control system.
 The indicator light does not come on.
 The indicator light flashes again.
 The indicator light goes out after it comes on.
If this is the case, contact your Lexus dealer and have your
Lexus inspected.

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REAR HEIGHT CONTROL AIRSUSPENSION
This rear height control air suspension controls the
vehicle height depending on the vehicle driving condition.
Select your desired height among the “HI” (high), “N”
(normal) and “LO” (low) modes with the height select
switch.
(a) Vehicle height modes
“N” (normal) mode: The vehicle height in this mode is
standard. Regardless of the number of occupants or the
luggage loading condition, the vehicle height is always
automatically adjusted to a fixed height in any mode while the
engine is running.
This mode is suitable for ordinary driving. “HI”
(high) mode: The vehicle height is about 40 mm (1.6 in.)
higher at the rear than the “N” mode height.
This mode is suitable when driving on the bumpy roads and
through water.
However, when the vehicle speed exceeds about 30 km/h (19
mph) or over in the “HI” mode, the “N” mode is automaticall\
y
selected.
CAUTION
The “HI” mode should be used for severe offroad
driving condition only. As the vehicle’s center of gravity
is higher in this setting, the vehicle may become
unstable when turning abruptly resulting in accident.
“LO” (low) mode: The vehicle height is about 20 mm (0.8 in.)
lower at the rear than the “N” mode height.
This mode allows you easy access to the vehicle (getting in and
out) and easy loading and unloading operation.
This mode is available when the vehicle speed is under about
12 km/h (7 mph).

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NOTICE
Use the “LO” mode when the vehicle is stopped.
Otherwise, when the vehicle speed exceeds about 12
km/h (7 mph), “N” mode is selected automatically. So
be careful when you drive in any place where the
overhead height is limited.
(b) Vehicle height mode changing condition
To change the vehicle height, it is necessary to meet the
following conditions.
The engine should be running.
 The height control “OFF” indicator light should go off.
 When selecting a mode, there is a vehicle speed limit. Refer
to the following table.
Yes = The mode can be selected.
No = The mode cannot be selected.
“LO”
mode“N”
mode“HI”
mode
Under about
12 km/h (7 mph)Ye sYe sYe s
Under about
30 km/h (19 mph)NoYe sYe s
About 30 km/h
(19 mph) or overNoYe sNo
In the following cases, the rear height control suspension
will not operate.
 The underbody of the vehicle has touched the surface on
bumpy roads.
 The area around the rear suspension is coated with ice.
If the vehicle is moved to its usual location or the ice is removed
and the height select switch is pressed, the vehicle height
control cannot be operated. In this case, turn off and restart the
engine, then push the control switches.
(c) Vehicle height adjustment
1Higher2Lower
To change the mode, push the height select switch on
either side of “ ” (higher) or “
” (lower).

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368The height control indicator light indicates which mode is
selected. (See “(e) Height control indicator light” described
below.)

Selecting the “HI” mode
Push the height select switch on the “ ” side when the vehicle
speed is under about 30 km/h (19 mph).
To change the “N” mode to “HI”: Push the switch once.
To change the “LO” mode to “HI”: Push the switch twice. It
takes about 30 seconds until the “LO” mode changes to the “HI”
mode.
 Selecting the “N” mode
To change the “HI” mode to “N”: Push the height select
switch on the “
” side once.
To change the “LO” mode to “N”: Push the height select
switch on the “ ” side once.
 Selecting the “LO” mode
Push the height select switch on the “
” side while the vehicle
is stopped.
To change the “N” mode to “LO”: Push the switch once.
To change the “HI” mode to “LO”: Push the switch twice.
Even if the engine is stopped while the vehicle height is being
lowered, the operation continues for up to 25 seconds. If within
this 25 seconds, any of the side doors or the back door is
opened, operation will continue for a further 15 seconds.
NOTICE
 If the vehicle height is changed frequently when the
vehicle is heavily loaded, the compressor may
overheat causing the vehicle height adjustment
operation to stop.
 Before you lower the vehicle height with the height
select switch, check under the vehicle to make sure
nothing to damage the vehicle or no one to be injured
is there and that the underbody of the vehicle does
not touch the ground.
 After unloading, the height of a vehicl e equipped with
the rear height control air suspension becomes
slightly higher than the normal vehicle height. Take
sufficient care where the overhead height is
restricted.
 Do not select the “LO” mode in the bumpy roads. If
the underbody of the vehicle touches the rugged
road surface, the vehicle may be damaged.

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(d) Turning off the rear height control airsuspension
To turn off the rear height control air suspension with the
vehicle stopped, push the “HEIGHT CONTROL OFF”
switch. The height control “OFF” indicator light comes on
and the vehicle height is fixed in the same mode as the
height control switch is pushed.
This status is memorized in the system even after the engine
is stopped.
If you push the switch again, the height control “OFF” indicator
light goes out and the rear height control air suspension is
turned on.
Even after the rear height control air suspension is turned off
with the “HEIGHT CONTROL OFF” switch, if the vehicle speed
exceeds 30 km/h (19 mph), the rear height control air
suspension automatically selects the “N” mode.
CAUTION
If you drive through deep water over about 700 mm (28
in.) in depth, put the vehicle height in the “HI” mode with
the height select switch and then turn off the rear height
control air suspension by pushing the “HEIGHT
CONTROL OFF” switch.
NOTICE
 When jacking up or installing tire chains, be sure to
turn off the rear height control air suspension with
the “HEIGHT CONTROL OFF” switch and stop the
engine. Otherwise, the vehicle height may change
because of the automatic leveling function resulting
in accident.
 If your vehicle must be towed, put the vehicle height
in the “N” mode and turn off the rear height control air
suspension. Otherwise, the vehicle height may
change because of the automatic leveling function
resulting in accident.
 If your vehicle gets ditched, turn off the rear height
control air suspension with the “HEIGHT CONTROL
OFF” switch. Otherwise, the vehicle height may
change because of the automatic leveling function
resulting in accident.

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(f) Parking and stopping tips
If you immediately stop the engine to park the vehicle after
off−road driving, the vehicle height is lowered slightly as the
vehicle becomes cool. When parking, make sure there is
nothing that will be in contact with the underbody of the vehicle.
When you start the engine, the vehicle returns to the previous
height.
If you park the vehicle for a long time, the vehicle height may
be gradually lowered. When parking for a long time, make sure
there is nothing that will be in contact with the underbody of the
vehicle. When you start the engine, the vehicle returns to the
previous height.
If you stop the engine, the vehicle height may change in
accordance with the change in the temperature. When you
start the engine, the vehicle returns to the previous height.
(g) Rear height control failure warning
If there is a problem somewhere in the rear height control air
suspension, the “N” mode is automatically selected. If this
occurs, the height control “OFF” indicator light blinks and the
vehicle height control cannot be activated until the malfunction
is corrected. If this is the case, bring your vehicle to your Lexus
dealer as soon as possible and have it checked.
ELECTRONIC MODULATED SUSPENSION
This electronic modulated suspension adjusts the
damping effect on the shock absorbers with the control
switch. Select one of the 4 modes which is suited to the
driving conditions with the control switch to provide good
riding comfort and stability.
1For driving on a bumpy road
2For ordinary driving such as in the city traffic
3For moderate high speed driving
4For sporty type driving such as on winding mountain
roads and high speed driving
5Soft
6Firm

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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 “ON”. 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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VEHICLE STABILITY CONTROLSYSTEM
The vehicle stability control system helps provide
integrated control of the systems such as antilock 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.