2003 Lexus GX470 check engine

DRIVING TIPS
343
CAUTION
Always observe the following precautions to minimize
the risk of serious personal injury or damage to your
vehicle:
Drive carefully when off the road. Do not take
unnecessary risks by driving in dangerous places.
 Do not grip the steering wheel spokes when driving
offroad. A bad bump could jerk the wheel and injure
your hands. Keep both hands and especially your
thumbs on the outside of the rim.
 Always check your brakes for effectiveness
immediately after driving in sand, mud, water or
snow.
 After driving through tall grass, mud, rock, sand,
rivers, etc., check that there is no grass, bush, paper,
rags, stone, sand, etc. adhering or trapped on the
underbody. Clear off any such matter from the
underbody. If the vehicle is used with these materials
trapped or adhering to the underbody, a breakdown
or fire could occur.
 In a rollover crash, an unbelted person is
significantly more likely to die than a person wearing
a seat belt. Therefore, the driver and all passengers
should fasten their seat belts whenever the vehicle is
moving.
 When driving offroad 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.
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 ef ficiency
and may damage brake system components.

DRIVING TIPS
344
Always perform a maintenance inspection after each
day of offroad driving that has taken you through
rough terrain, sand, mud, or water. For scheduled
maintenance information, refer to the “Owner’s
Manual Supplement / Scheduled Maintenance”.
WINTER DRIVING TIPS
Make sure your coolant is properly protected against
freezing.
Your coolant must contain ethylene −glycol type coolant for a
proper corrosion protection of aluminum components. Use
“Toyota Genuine Long Life Coolant” or equivalent. See
“Checking the engine coolant level” on page 422 for
instructions.
NOTICE
Do not use alcohol type antifreeze or plain water alone.
When it is extremely cold, we recommend to use 60% solution
for your Lexus, to provide protection down to about −50C
(−58 F). Do not use more than 70% solution for better coolant
performance.
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 447 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 420 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.

DRIVING TIPS
345
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.
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.

DRIVING TIPS
353
Trailer lights
 Socket for trailer lights
Your vehicle is equipped with a wire harness stored in the rear
end underbody. Models with weight carrying hitch receiver are
fitted with a socket for trailer lights under the rear bumper. Use
either of them to connect and operate the trailer lights.
However, the trailer lights must comply with federal,
state/provincial and local regulations. See your local
recreational vehicle dealer or rental agency for the correct type
of wiring and relays for your trailer. Check for correct operation
of the turn signals and stop lights each time you hitch up. Direct
splicing may damage your vehicle’s electrical system and
cause a malfunction of your lights.
Breakin schedule
Lexus recommends that you do not tow a trailer with a new
vehicle or a vehicle with any new power train component
(engine, transmission, differential, wheel bearing, etc.) for the
first 800 km (500 miles) of driving.
Maintenance
 If you tow a trailer, your vehicle will require more frequent
maintenance due to the additional load. For this
information, please refer to the scheduled maintenance
information in the “Owner’s Manual Supplement /
Scheduled Maintenance”.
 Retighten all fixing bolts of the towing ball and bracket after
approximately 1000 km (600 miles) of trailer driving.
Connecting a trailer
Stop your vehicle and a trailer in line and perform the following:
1. Put the rear height control air suspension in the “LO” (low)
mode. Turn the ignition switch off or push the “HEIGHT
CONTROL OFF” switch to turn off the rear height control air
suspension.
2. Connect a trailer.
3. Turn the ignition switch on or push the “HEIGHT CONTROL
OFF” switch to turn on the rear height control air suspension.
Select the “N” (normal) mode with the height select switch.
Disconnecting a trailer
Stop your vehicle and a trailer in line and perform the following:
1. Put the rear height control air suspension in the “LO” (low)
mode. (Make sure the vehicle height is in the “LO” (low) mode
by pushing the height select switch on the “
” side.)
2. Turn the ignition switch off or push the “HEIGHT CONTROL
OFF” switch to turn off the rear height control air suspension.

DRIVING TIPS
356When restarting out after parking on a slope:
1. With the transmission in “P” position, start the engine. Be
sure to keep the brake pedal depressed.
2. Shift into the “3”, “2”, “L” or “R” position.
3. Release the parking brake and brake pedal and slowly pull
or back away from the wheel blocks. Stop and apply your
brakes.
4. Have someone retrieve the blocks.
CAUTION

Do not exceed 72 km/h (45 mph) or the posted towing
speed limit, whichever is lower. Because instability
(swaying) of a towing vehicletrailer combination
usually increases as the speed increases, exceeding
72 km/h (45 mph) may cause loss of control.
 Slow down and downshift before descending steep
or long downhill grades. Do not make sudden
downshifts.
 Avoid holding the brake pedal down too long or too
frequently. This could cause the brakes to overheat
and result in reduced braking efficiency.
HOW TO SAVE FUEL AND MAKE
YOUR VEHICLE LAST LONGER
Improving fuel economy is easy − just take it easy. It will help
make your vehicle last longer, too. Here are some specific tips
on how to save money on both fuel and repairs:
 Keep your tires inflated at the correct pressure. Check
the pressure every two weeks, or at least once a month.
Underinflation causes tire wear and wastes fuel.
 Do not carry unneeded weight in your vehicle. Excess
weight puts a heavier load on the engine, causing greater
fuel consumption.
 Avoid lengthy warmup idling. Once the engine is
running smoothly, begin driving − but gently. Remember,
however, that on cold winter days this may take a little
longer.
 Always keep the automatic transmission selector lever
in the “D” position when engine braking is not required.
Driving with the overdrive off will reduce the fuel economy.
(For details, see “Automatic transmission” on page 303.)
 Accelerate slowly and smoothly. Avoid jackrabbit starts.
 Avoid long engine idling. If you have a long wait and you
are not in traffic, it is better to turn off the engine and start
again later.
 Avoid engine overrevving. Use a gear position suitable
for the road on which you are traveling.

IN CASE OF AN EMERGENCY
359
IF YOUR ENGINE STALLS WHILEDRIVING
If your engine stalls while driving ...
1. Reduce your speed gradually, keeping a straight line. Move
cautiously off the road to a safe place.
2. Turn on your emergency flashers.
3. Turn the ignition key to “ACC” or “LOCK”, and try starting
the engine again.
If the engine will not start, see “If your vehicle will not start”\
.
CAUTION
If the engine is not running, the power assist for the
brakes and steering will not work, so steering and
braking will be much harder than usual.
IF YOUR VEHICLE WILL NOT START
(a) Simple checks
Before making these checks, make sure you have followed the
correct starting procedure instructions in “How to start the
engine” on page 302 and that you have sufficient fuel. Since
your vehicle is equipped with the engine immobiliser system,
also check whether the other keys will start the engine. If they
work, your key may be broken. Have the key checked at your
Lexus dealer. If none of your keys work, there may be a
malfunction in the immobiliser system. Call your Lexus dealer.
See “Keys” on page 8.
If the engine is not turning over or is turning over too
slowly
1. Check that the battery terminals are tight and clean.
2. If the battery terminals are O.K., switch on the interior light.
3. If the light is out, dim or goes out when the starter is cranked,
the battery is discharged. You may try jump starting. See “(c)
Jump starting” for further instruction.
If the light is O.K., but the engine still will not start, it needs
adjustment or repair. Call a Lexus dealer, Roadside
Assistance or Customer Service Assistance. (See
“Foreword”.)

IN CASE OF AN EMERGENCY
362JUMP STARTING PROCEDURE
1. If the booster battery is installed in another vehicle, make
sure the vehicles are not touching. Turn off all unnecessary
lights and accessories.
2. If required, remove all the vent plugs from the booster
battery. Lay a cloth over the open vents on the booster battery.
(This
helps reduce the explosion hazard, personal injuries and
burns.)
If the booster battery is an extended maintenance interval
battery, it is not necessary to remove the vent plugs.
3. If the engine in the vehicle with the booster battery is not
running, start it and let it run for about 5 minutes. During jump
starting, run the engine at about 2000 rpm with the accelerator
pedal lightly depressed.
4. Locate positive (+) and negative ( −) terminals of each
battery. Connect the jumper cables in the exact order (
1
2
3
4
) shown in the illustration.
1Connect a positive (red) jumper cable clamp to the
positive (+) terminal of the discharged battery.
2Connect the clamp at the other end of the positive (red)
cable to the positive (+) terminal of the booster battery.
3Connect a negative (black) cable clamp to the negative
(−) terminal of the booster battery.
4Connect the clamp at the other end of the negative (black)
cable to a solid, stationary, unpainted metallic point (e.g.
engine hanger) away from the battery. Do not connect it
to or near any part that moves when the engine is
cranked.
CAUTION
When making the connections, to avoid serious injury,
do not lean over the battery or accidentally let the
jumper cables or clamps touch anything except the
correct battery terminals or the ground.
5. Start your engine in the normal way. After starting, run it at
about 2000 rpm for several minutes with the accelerator pedal
lightly depressed.
6. Carefully disconnect the cables in the exact reverse order:
the negative cable and then the positive cable.
7. Carefully dispose of the battery cover cloths which may
now contain sulfuric acid.
8. If removed, replace all the battery vent plugs.
If the cause of your battery discharging is not apparent (for
example, lights left on), you should have it checked at your
Lexus dealer.

IN CASE OF AN EMERGENCY
363
IF YOU CANNOT INCREASE THEENGINE SPEED
If the engine speed does not increase with the accelerator
pedal depressed down, there may be a problem somewhere
in your electronic throttle control system.
At this time, vibration may occur. However, if you depress the
accelerator pedal more firmly and slowly, you can drive your
vehicle at low speeds. Have your vehicle checked by your
Lexus dealer as soon as possible.
Even if the abnormality of the electronic throttle control system
is corrected during low speed driving, the system may not be
recovered until the engine is stopped and the ignition key is
turned to “ACC” or “LOCK” position.
CAUTION
Be especially careful to prevent erroneous pedal
operation.
IF YOUR VEHICLE OVERHEATS
If your engine coolant temperature gauge indicates
overheating, if you experience a loss of power, or if you
hear a loud knocking or pinging noise, the engine has
probably overheated.
When the engine overheats
Pull safely off the road, stop the vehicle and turn on your
emergency flashers. Put the transmission in “P” and apply the
parking brake.
A: If steam is coming from your engine:
Turn off the engine. Leave the hood closed until there is no sign
of steam or coolant. Your engine could have been seriously
damaged already. Call your Lexus dealer for assistance.
CAUTION
To help avoid personal injury, keep the hood closed until
there is no steam. Escaping steam or coolant is sign of
very high pressure.