2004 Lexus GX470 engine

STARTING AND DRIVING
393
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 Lº position,
push the DACº 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 surfaces 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 Lº
position.
The system will not operate if the four-wheel drive control lever
is in the Hº position.
2. In order to make full use of the engine brake, putting the
transmission in Lº or 2º is recommended.
The system will operate even if the transmission selector lever
is in Dº, 4º, 3º or Nº. However, when it is in Lº or 2º the
engine brake can also be utilized enabling the system to
operate more effectively.
3. Push the DACº switch to turn the system on. The
downhill assist control system indicator light on the
instrument panel will come on.
If the downhill assist control system indicator light flashes, the
transmission selector lever may be in Nº or four-wheel drive
control lever may be in the Hº position.

STARTING AND DRIVING
399 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 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 brake 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
402
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 60.
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.
BRAKE PAD WEAR LIMIT
INDICATORS
The brake pad wear limit indicators on your disc brakes
give a warning noise when the brake pads are worn to the
extent that replacement is required.
If you hear a squealing or scraping noise while driving, have the
brake pads checked and replaced by your Lexus dealer as
soon as possible. Expensive rotor damage can result if the
pads are not replaced when needed.

STARTING AND DRIVING
403
LIMITED-SLIP DIFFERENTIAL
Your Lexus is equipped with a limited-slip center differential
(transfer).
If one wheel Ð either front or rear Ð begins to spin, the transfer
(limited-slip center differential) is designed to aid traction by
automatically transmitting driving force to the wheels on the
other drive axle. It transmits driving force to the front wheels
if a rear wheel spins, and to the rear wheels if a front wheel
spins.
CAUTION
Do not start or run the engine while your vehicle is
supported by a jack. The vehicle could be driven off the
jack and could pose a danger or result in serious injury.
NOTICE
Use only a spare tire of the same size, construction and
load capacity as the original tires on your Lexus
because damage to the limited-slip differential could
possibly occur with another tire type.

DRIVING TIPS
407
When driving off-road or in rugged terrain, do not
drive at excessive speeds, jump, make sharp turns,
strike objects, etc. This may cause loss of control or
vehicle rollover causing death or serious injury. You
are also risking expensive damage to your vehicle's
suspension and chassis.
Do not drive horizontally across steep slopes.
Driving straight up or straight down is preferred.
Your vehicle (or any similar off-road vehicle) can tip
over sideways much more easily than forward or
backward.BREAK-IN PERIOD
Drive gently and avoid high speeds.
You need not follow a break-in schedule with your new Lexus.
But following a few simple tips for the first 1600 km (1000 miles)
can add to the future economy and long life of your vehicle:
Avoid full throttle acceleration when starting and driving.
Avoid racing the engine.
Try to avoid hard stops during the first 300 km (200 miles).
Do not drive for a long time at any single speed, either fast
or slow.
Do not tow a trailer during the first 800 km (500 miles).

DRIVING TIPS
409
CAUTION
Before driving off, make sure the parking brake is
fully released and that the parking brake reminder
light is off.
Do not leave your vehicle unattended while the
engine is running.
Do not rest your foot on the brake pedal while driving.
It can cause dangerous overheating, needless wear,
and poor fuel economy.
To drive down a long or steep hill, reduce your speed
and downshift. Remember, if you ride the brakes
excessively, they may overheat and not work
properly. See page 368.
Be careful when accelerating, upshifting,
downshifting or braking on a slippery surface. The
abrupt change in engine speed, such as sudden
acceleration or engine braking, could cause the
vehicle to spin or skid.
Do not drive in excess of the speed limit. Even if the
legal speed limit permits it, do not drive over 140 km/h
(85 mph) unless your vehicle has high-speed
capability tires. Driving over 140 km/h (85 mph) may
result in tire failure, loss of control and possible
injury. Be sure to consult a tire dealer to determine
whether the tires on your vehicle are high-speed
capability tires or not before driving at such speeds.

DRIVING TIPS
413
NOTICE
If driving through water, such as when crossing
shallow streams, first check the depth of the water
and the bottom of the river bed for firmness. Drive
slowly and avoid deep water.
Take all necessary safety measures to ensure that
water damage to the engine or other components
does not occur.
Water entering the engine air intake will cause severe
engine damage.
Water can wash the grease from wheel bearings,
causing rusting and premature failure, and may also
enter the differentials, transmission and transfer
case, reducing the gear oil's lubricating qualities.
Sand and mud that has accumulated in brake drums
and around brake discs may affect braking efficiency
and may damage brake system components.
Always perform a maintenance inspection after each
day of off-road driving that has taken you through
rough terrain, sand, mud, or water. For scheduled
maintenance information, refer to the Owner's
Manual Supplement/Scheduled Maintenanceº.

DRIVING TIPS
414
WINTER DRIVING TIPS
Make sure your coolant is properly protected against
freezing.
Only use Toyota Super Long Life Coolantº or similar high
quality ethylene glycol based non- silicate, non- amine,
non- nitrite, and non- borate coolant with long- life hybrid
organic acid technology.
See Checking the engine coolant levelº on page 519 for
details of coolant type selection.
Toyota Super Long Life Coolantº is pre- mixed with 50%
coolant and 50% deionized water. This coolant provides
protection down to about -35C (-31F).
NOTICE
Do not use plain water alone.
Check the condition of the battery and cables.
Cold temperatures reduce the capacity of any battery, so it
must be in top shape to provide enough power for winter
starting. Page 562 tells you how to visually inspect the battery.
Your Lexus dealer and most service stations will be pleased to
check the battery charge level.Make sure the engine oil viscosity is suitable for the cold
weather.
See page 518 for recommended viscosity. Leaving a heavy
summer oil in your vehicle during winter months may cause
harder starting. If you are not sure about which oil to use, call
your Lexus dealer Ð they will be pleased to help.
Check the electronic ignition system for loose
connections or obvious damage.
Keep the door locks from freezing.
Squirt lock de-icer or glycerine into the locks to keep them from
freezing.