engine lexus LS400 1998 Electrical Components / LEXUS 1998 LS400 (OM50498U) Service Manual

STARTING AND DRIVING
166
(f) Good driving practice
If the transmission repeatedly upshifts and downshifts between
the fourth and overdrive gears when climbing a gentle slope, shift
the selector lever to the ”4” position. Be sure to shift the selector
lever to the ”D” position after climbing the slope.
When towing a trailer, in order to maintain efficient engine
braking and electrical charging performance, do not use
overdrive. The selector lever must be in the ”4” position.
CAUTION
Always keep your foot on the brake pedal while stopped with
the engine running. This prevents the vehicle from creeping.
NOTICE
Do not hold the vehicle on an upgrade with the accelerator
pedal. This can cause the transmission to overheat. Always use
the brake pedal or parking brake.
(g) Rocking your vehicle if stuck
CAUTION
If your vehicle becomes stuck in snow, mud, sand, etc., then
you may attempt to rock the vehicle free by moving it forward
and backward. Do not attempt this procedure if people or
objects are anywhere near the vehicle. During the rocking
operation the vehicle may suddenly move forward or back as
it becomes unstuck, causing injury or damage to nearby
people or objects.
NOTICE
If you rock your vehicle, observe the following precautions to
prevent damage to the transmission and other parts.
Do not depress the accelerator pedal while shifting the
selector lever or before the transmission is completely shifted
to forward or reverse gear.
Do not race the engine and avoid spinning the wheels.
If your vehicle remains stuck after rocking the vehicle several
times, consider other ways such as towing.

STARTING AND DRIVING
167
(h) If you cannot shift the selector lever
If you cannot shift the selector lever even though the brake pedal is
depressed, use the shift lock override button. For instructions, see
”If you cannot shift automatic transmission selector lever” on page
209.
(i) If the ”ECT PWR” indicator light flashes
If the ”ECT PWR” indicator light flashes, contact your Lexus dealer
as soon as possible. There may be trouble in the transmission
system.
ELECTRONIC THROTTLE
CONTROL SYSTEM
The electronic throttle control system always maintains
appropriate engine output in relation to the accelerator opening
in all driving conditions.
31L0082
1
Power mode 2
Normal mode 3
Snow mode
The electronic throttle control system has 3 modes: Normal,
Power and Snow modes.
Normal mode: For ordinary driving, Lexus recommends that you
use the normal mode to improve fuel economy.
Power mode: For more powerful acceleration and sporty driving.

STARTING AND DRIVING
168In the power mode, the ”ECT PWR” light in the instrument cluster
is on and the transmission is shifted up at higher vehicle speeds and
shifted down more responsively than is the normal mode.
To return to the normal mode, push the driving pattern selector
switch lightly on the ”SNOW” side.
Snow mode: For slippery road surfaces such as in snow. In this
mode, the spinning of the rear wheels is controlled appropriately.
When you push the driving pattern selector switch on the ”SNOW”
side, the snow mode is turned on and the ”ECT SNOW” light in the
instrument cluster comes on.
To return to the normal mode, push the driving pattern selector
switch on the ”SNOW” side again.
When you turn the ignition switch off in the snow mode, the mode
automatically changes to the normal mode.
CRUISE CONTROL
The cruise control allows you to cruise the vehicle at a desired
speed over 40 km/h (25 mph) with your foot off the accelerator
pedal.
Your cruising speed can be maintained although a slight speed
change may occur when driving up or down a gradient, within the
limits of engine performance. On steeper hills, a great speed change
will occur so it is better to drive without the cruise control.
When the cruise control is on, the driving pattern of the automatic
transmission is fixed in the normal position, regardless of the
position of the selector switch.
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.

STARTING AND DRIVING
170If the vehicle speed falls below about 40 km/h (25 mph), the preset
speed will be automatically cancelled.
If the vehicle speed drops 16 km/h (10 mph) below the preset speed,
the preset speed will also automatically be cancelled.
If the preset speed automatically cancels out for other than these
reasons, have your vehicle checked by your Lexus dealer at the
earliest opportunity.
Resetting to a faster speed
Press the control lever upward in the ”RES/ACC” direction and hold
it. Release the lever when the desired speed is attained. While the
lever is held upward, the vehicle will gradually gain speed.
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 increased 1.6
km/h (1 mph) each time by pressing the control lever upward in the
”RES/ACC” direction quickly within 0.6 seconds.
However, a quicker way to reset is to accelerate the vehicle and then
press the control lever downward in the ”SET/COAST” direction.
Resetting to a slower speed
Press the control lever downward in the ”SET/COAST” 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 pressing the control lever downward in
the ”SET/COAST” direction quickly within 0.6 seconds.
However, a quicker way to reset is to depress the brake pedal and
then press the control lever downward in the ”SET/COAST”
direction.
Even if you downshift the transmission from the ”D” position to ”4”
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.
Resuming the preset speed
If the preset speed is cancelled by pulling the control lever or by
depressing the brake pedal, pushing the lever up in the ”RES/ACC”
direction will restore the speed set prior to cancellation. However,
once the vehicle speed falls below about 40 km/h (25 mph), the
preset speed will not be resumed.

STARTING AND DRIVING
174
VEHICLE SKID CONTROL SYSTEM
The vehicle skid control system helps to provide comprehensive
control of the systems such as an antilock brake system,
traction control, engine control, electronically modulated air
suspension, 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 abrupt steering
wheel operation occurs.
31L0521
Slip indicator light
If the vehicle is going to skid during driving, the slip indicator light
flashes and an alarm sounds.
The vehicle skid control activates when the vehicle speed is about
more than 15 km/h (9 mph).Depressing the brake pedal repeatedly causes a small noise from the
engine compartment. This is a pump pulsating sound of the brake
system and it is not a malfunction.
You may hear a slight clicking noise in the engine compartment for
a few seconds when the engine is started or just after the vehicle is
started. This means that the vehicle skid control is in the selfcheck
mode and does not indicate a malfunction.
31L017-2
You can turn off the vehicle skid control system by pushing the
”VSC OFF” switch. The ”VSC OFF” indicator comes on. At
this time, the traction control system also turns off. You cannot
turn off either one of them. Pushing the ”VSC OFF” switch a
second time turns the system back on and extinguishes the ”VSC
OFF” indicator light.
When you turn the ignition switch on, this system always turns on.

STARTING AND DRIVING
176
CAUTION
Do not rely excessively on the vehicle skid control system.
Even if the vehicle skid control system is operating, it is not
that your vehicle is absolutely safe. Reckless driving will
result in an unexpected accident. Always keep safety
driving in mind. If the slip indicator light flashes, sounding
an alarm, 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 skid control system may not function
correctly. When replacing the tires or wheels, contact your
Lexus dealer.
BRAKE SYSTEM
The tandem master cylinder brake system is a hydraulic system with
two separate subsystems. If either subsystem should fail, the other
will still work. However, the pedal will be harder to press, and your
stopping distance will be longer. 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 powerassist 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
reserve 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 vacuum 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 be
longer.

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177
Antilock brake system
The antilock brake system is designed to automatically help
prevent lockup 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.
The antilock 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).
You may hear a sound in the engine compartment for a few seconds
when the engine is started or just after the vehicle is started. This
means that the antilock brake system is in the selfcheck mode, and
does not indicate a malfunction.
Effective way to press the ABS brake pedal: When the antilock
brake system function is in action, you may feel the brake pedal
pulsating and hear a noise. In this situation, to let the antilock brake
system work for you, just hold the brake pedal down more firmly.
Do not pump the brake. This will result in reduced braking
performance.
The brake pedal pulsation caused by the antilock brake system may
indicate hazardous road surface conditions. Although the antilock
brake system assists in providing vehicle control, it is still important
to drive with all due care, because the antilock brake system cannot
overcome the laws of physics that act on your vehicle:
Braking capability is dependent on tire friction with the road
surface.Even though the antilock brake system is operating, a driver
cannot maintain full control on certain slippery road surfaces,
when cornering at high speeds, or in violent maneuvers.
Avoid high speeds on wet roads. The antilock brake system
cannot eliminate the risk of hydroplaning and loss of tire friction.
Always maintain a safe distance from the vehicle in front of you.
Compared with vehicles not fitted with an antilock brake system,
your vehicle may require a longer stopping distance in the following
cases:
Driving on rough, gravel or snowcovered roads.
Driving with tire chains installed.
Driving on roads where the road surface is pitted or has other
differences in surface height.

DRIVING TIPS
181
BREAKIN PERIOD
Drive gently and avoid high speeds.
You need not follow a breakin 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:
Do not drive over 88 km/h (55 mph).
Avoid overrevving. Maintain engine speed between 2000 and
4000 rpm.
Avoid fullthrottle starts.
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).
OPERATION IN FOREIGN
COUNTRIES
If you plan to drive your Lexus in another country ...
First, comply with the vehicle registration laws.
Second, confirm the availability of the correct fuel (unleaded and
minimum octane rating).
TIPS FOR DRIVING IN VARIOUS
CONDITIONS
Always slow down in gusty crosswinds. This will allow you
much better control.
Drive slowly onto curbs and, if possible, at a right angle. Avoid
driving onto high, sharpedged objects and other road hazards.
Failure to do so can lead to severe tire damage resulting in tire
bursts.
When parking on a hill, turn the front wheels until they touch the
curb so that the vehicle will not roll. Apply the parking brake, and
place the transmission in ”P”. If necessary, block the wheels.
Washing your vehicle or driving through deep water may get the
brakes wet. To see whether they are wet, check that there is no
traffic near you and then press the pedal lightly. If you do not feel
a normal braking force, the brakes are probably wet. To dry them,
drive the vehicle cautiously while lightly pressing the brake pedal
with the parking brake applied. If they still do not work safely,
pull to the side of the road and call a Lexus dealer for assistance.
CAUTION
Before driving off, make sure the parking brake is fully
released and that the parking brake reminder light is off.

DRIVING TIPS
182Do 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 163.
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 highspeed 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
highspeed capability tires or not before driving at such
speeds.
Do not continue normal driving when the brakes are wet.
If they are wet, your vehicle will require a longer stopping
distance, and it may pull to one side when the brakes are
applied. Also, the parking brake will not hold the vehicle
securely.
WINTER DRIVING TIPS
Make sure you have ethyleneglycol antifreeze in the radiator.
NOTICE
Do not use alcohol type antifreeze.
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 253
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 232 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
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 deicer or glycerine into the locks to keep them from
freezing.

DRIVING TIPS
183 Use a washer fluid containing an antifreeze solution.
This product is available at your Lexus dealer and most auto parts
stores. Follow the manufacturer’s directions for how much to mix
with water.
NOTICE
Do not use engine antifreeze or any other substitute because it
may damage your vehicle’s paint.
Do not use your parking brake when there is a possibility it could
freeze.
When parking, put the transmission into ”P” and block the front
wheels. Do not use the parking brake, or snow or water accumulated
in and around the parking brake mechanism may freeze the parking
brake, making it hard to release.
Keep ice and snow from accumulating under the fenders.
Ice and snow built up under your fenders can make steering difficult.
During bad winter driving, stop and check under the fenders
occasionally.
Depending on where you are driving, we recommend you carry
some emergency equipment.
Some of the things you might put in the vehicle are tire chains,
window scraper, bag of sand or salt, flares, small shovel, jumper
cables, etc.
TRAILER TOWING
Your vehicle is designed primarily as a passengercarrying vehicle.
Towing a trailer will have an adverse effect on handling,
performance, braking, durability and driving economy (fuel
consumption, etc.). Your safety and satisfaction depend on the
proper use of correct equipment and cautious driving habits. For
your safety and the safety of others, you must not overload your
vehicle or trailer. Lexus warranties do not apply to damage or
malfunction caused by towing a trailer for commercial purposes.
Ask your local Lexus dealer for further details before towing.
NOTICE
When towing a trailer, be sure to consult your Lexus dealer for
further information on additional requirements.
Weight limits
Before towing, make sure the total trailer weight, gross vehicle
weight, gross axle weight and trailer tongue load are all within
the limits.
The total trailer weight and tongue load can be measured with
platform scales found at a highway weighing station, building
supply company, trucking company, junk yard, etc.