2003 TOYOTA TUNDRA cooling

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The gauge indicates the engine coolant
temperature when the ignition switch is
on. The engine operating temperature
will vary with changes in weather and
engine load.
If the needle moves into the red zone,
your engine is too hot. If your vehicle
overheats, stop your vehicle and allow the
engine to cool.
Your vehicle may overheat during severe
operating conditions, such as:
Driving up a long hill on a hot day.
Reducing speed or stopping after high
speed driving.
Idling for a long period with the air
conditioning on in stop−and− go traffic.
Towing a trailer.
NOTICE
Do not remove the thermostat in
the engine cooling system as this
may cause the engine to overheat.
The thermostat is designed to con-
trol the flow of coolant to keep the
temperature of the engine within
the specified operating range.
 Do not continue driving with an
overheated engine. See “If your ve-
hicle overheats” in Section 4.
IdlingNormal
driving
The oil pressure gauge indicates engine
oil pressure when the ignition switch is
on. Check it while driving to make sure
that the needle is in the proper range.
If the oil pressure should stay below the
normal range, pull off the road to a safe
place and stop the engine immediately.
Call a Toyota dealer or qualified repair
shop for assistance.
Oil pressure may not build up when the
oil level is too low. The oil pressure
gauge is not designed to indicate oil level,
and the oil level must be checked using
the level dipstick.
Oil pressure gauge

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Fan speed selector
Turn the knob to adjust the fan speed—to
the right to increase, to the left to de-
crease.
Temperature selector
Turn the knob to adjust the temperature—
to the right to warm, to the left to cool.
Air flow selector
Turn the knob to select the vents used for
air flow.
1. Panel— Air flows mainly from the
instrument panel vents.
2. Bilevel— Air flows from both the floor
vents and the instrument panel vents.
3. Floor— Air flows mainly from the floor
vents.
It is recommended that you close the
lower vent. For details about this, see
“Instrument panel vents” in this section. 4. Floor/Windshield—
Air flows mainly
from the floor vents and windshield
vents.
Turning the air flow selector to the
floor/windshield position turns on the
defogging function with the purpose of
clearing the front view.
This position allows the air intake to
select FRESH automatically. This is to
clean up the front view more quickly.
It is recommended that you close the
lower vent. For details about this, see
“Instrument panel vents” in this section.
Vehicles with “A/C” button—
Press the “A/C” button for dehumidified
heating or cooling. This setting clears
the front view more quickly.

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5. Windshield—Air flows mainly from the
windshield vents.
Turning the air flow selector to the
windshield position turns on the defog-
ging function with the purpose of clear-
ing the front view.
This position allows the air intake to
select FRESH automatically. This is to
clean up the front view more quickly.
It is recommended that you close the
lower vent. For details about this, see
“Instrument panel vents” in this section.
Vehicles with “A/C” button—
Press the “A/C” button for dehumidified
heating or cooling. This setting clears
the front view more quickly.
For details about air flow selector settings,
see “Air flow selector settings” described
below. Air intake selector
The air intake selector button is used to
switch the air intake
FRESH mode that
draws outside air into the system and
RECIRCULATED mode that recirculates
the air inside vehicle.
To turn the air source to RECIRCULATED
mode, press the button. The indicator will
come on. To turn the air source to FRESH
mode, press the button again. The indica-
tor will go off.
To prevent fogging up of the windshield,
the air intake mode may change automati-
cally to FRESH depending on the condi-
tion of the air conditioning system.
“A/C” button
To turn on the air conditioning, press the
“A/C” button. The “A/C” button indicator
will come on. To turn the air conditioning
off, press the button again.
Vehicles with 2UZ −FE engine—If the “A/C”
button indicator flashes, there is a prob-
lem in the air conditioning system and the
air conditioning automatically shuts off. If
this happens, take your vehicle to a
Toyota dealer for service.

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If following another vehicle on a dusty
road, or driving in windy and dusty
conditions, it is recommended that the
air intake selector be temporarily set to
RECIRCULATE, which will close off the
outside passage and prevent outside
air and dust from entering the vehicle
interior.
Heating
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s WARM
(red zone)
Air intake—FRESH (outside air)
Air flow—FLOOR
Lower vent—CLOSED
Air conditioning—OFF
For quick heating, select recirculated
air for a few minutes. To keep the
windows from fogging, select fresh af-
ter the vehicle interior has been
warmed.
Press the “A/C” button on for dehumidi-
fied heating.
Choose floor/windshield air flow to heat
the vehicle interior while defrosting or
defogging the windshield. Air conditioning
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s COLD
(blue zone)
Air intake—FRESH (outside air)
Air flow—PANEL
Air conditioning—ON
For quick cooling, move the air intake
selector to recirculate for a few min-
utes.
Ventilation
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s COLD
(blue zone)
Air intake—FRESH (outside air)
Air flow—PANEL
Air conditioning—OFF
Defogging
The inside of the windshield
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s WARM (red
zone) to heat; COLD
(blue zone) to cool
Air intake—FRESH (outside air)
Air flow—WINDSHIELD
Lower vent—CLOSED
Turning the air flow selector to the wind-
shield or floor/windshield position turns on
the defogging function with the purpose of
clearing the front view.
When turning the air flow selector to wind-
shield or floor/windshield position, the air
intake selects FRESH automatically. This
is to clean up the front view more quickly.
Vehicles with “A/C” button—
Press the “A/C” button for dehumidified
heating or cooling. This setting clears the
front view more quickly.
On humid days, do not blow cold air
on the windshield—the difference be-
tween the outside and inside tempera-
tures could make the fogging worse.

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Defrosting
The outside of the windshield
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s WARM
(red zone)
Air intake—FRESH (outside air)
Air flow—WINDSHIELD
Lower vent—CLOSED
Turning the air flow selector to the wind-
shield or floor/windshield position turns on
the defrosting function with the purpose of
clearing the front view.
When turning the air flow selector to wind-
shield or floor/windshield position, the air
intake selects FRESH automatically. This
is to clean up the front view more quickly.
Vehicles with “A/C” button—
Press the “A/C” button for dehumidified
heating or cooling. This setting clears the
front view more quickly.
To heat the vehicle interior while de-
frosting the windshield, choose floor/
windshield air flow.
Side vents
Lower vent
If air flow control is not satisfactory, check
the instrument panel vents. The instrument
panel vents may be opened or closed as
shown.
For removing frost or fog, it is recom-
mended that you close the lower vent
when using the “Floor”, “Floor/Windshield”
or “Windshield” mode.
Instrument panel vents

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Keep your engine in good running
order. Malfunctions in the engine
electrical system, electronic ignition
system/distributor ignition system
or fuel systems could cause an ex-
tremely high threeway catalytic
converter temperature.
 If the engine becomes difficult to
start or stalls frequently, take your
vehicle in for a checkup as soon
as possible. Remember, your Toyota
dealer knows your vehicle and its
threeway catalytic converter sys-
tem best.
 To ensure that the threeway cata-
lytic converter and the entire emis-
sion control system operate proper-
ly, your vehicle must receive the
periodic inspections required by the
Toyota Maintenance Schedule. For
scheduled maintenance information,
refer to the “Scheduled Maintenance
Guide” or “Owner ’s Manual Supple-
ment”.CAUTION
Avoid inhaling the engine exhaust.
It contains carbon monoxide, which
is a colorless and odorless gas. It
can cause unconsciousness or even
death.
Make sure the exhaust system has
no holes or loose connections. The
system should be checked from
time to time. If you hit something,
or notice a change in the sound of
the exhaust, have the system
checked immediately.
Do not run the engine in a garage
or enclosed area except for the
time needed to drive the vehicle in
or out. The exhaust gases cannot
escape, making this a particularly
dangerous situation.
Do not remain for a long time in a
parked vehicle with the engine run-
ning. If it is unavoidable, however,
do so only in an unconfined area
and adjust the heating or cooling
system to force outside air into the
vehicle.
To allow proper operation of your
vehicle’s ventilation system, keep
the inlet grilles in front of the wind-
shield clear of snow, leaves, or oth-
er obstructions.
If you smell exhaust fumes in the
vehicle, drive with the windows
open. Have the cause immediately
located and corrected.
Toyota does not recommend occu-
pying the rear cargo area when it
is fitted with a slidein camper,
camper shell or other type cover
while the engine is running. This
caution applies to both driving and
stopped or parked situations with
the engine running. Particular care
should be taken to prevent exhaust
gases from entering camper bodies,
trailers or other enclosures on or
around your vehicle. If exhaust
fumes are detected, open all win-
dows and thoroughly ventilate the
area.
Engine exhaust cautions

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FUNCTIONS OF ENGINE OIL
Engine oil has the primary functions of
lubricating and cooling the inside of the
engine, and plays a major role in main-
taining the engine in proper working order.
ENGINE OIL CONSUMPTION
It is normal that an engine should con-
sume some engine oil during normal
engine operation. The causes of oil
consumption in a normal engine are as
follows.
Oil is used to lubricate pistons, piston
rings and cylinders. A thin film of oil
is left on the cylinder wall when a pis-
ton moves downwards in the cylinder.
High negative pressure generated when
the vehicle is decelerating sucks some
of this oil into the combustion chamber.
This oil as well as some part of the oil
film left on the cylinder wall is burned
by the high temperature combustion
gases during the combustion process.
Oil is also used to lubricate the stems
of the intake valves. Some of this oil
is sucked into the combustion chamber
together with the intake air and is
burned along with the fuel. High tem-
perature exhaust gases also burn the
oil used to lubricate the exhaust valve
stems. The amount of engine oil consumed de-
pends on the viscosity of the oil, the
quality of the oil and the conditions the
vehicle is driven under.
More oil is consumed by high
−speed driv-
ing and frequent acceleration and decel-
eration.
A new engine consumes more oil, since
its pistons, piston rings and cylinder walls
have not become conditioned.
Oil consumption: Max. 1.0 L per 1000
km (1.1 qt./600 miles, 0.9 lmp. qt./600
miles)
When judging the amount of oil con-
sumption, note that the oil may become
diluted and make it difficult to judge
the true level accurately.
As an example, if a vehicle is used for
repeated short trips, and consumes a nor-
mal amount of oil, the dipstick may not
show any drop in the oil level at all, even
after 1000 km (600 miles) or more. This
is because the oil is gradually becoming
diluted with fuel or moisture, making it
appear that the oil level has not changed.
The diluting ingredients evaporate out
when the vehicle is then driven at high
speeds, as on an expressway, making it
appear that oil is excessively consumed
after driving at high speeds. IMPORTANCE OF ENGINE OIL LEVEL
CHECK
One of the most important points in prop-
er vehicle maintenance is to keep the en-
gine oil at the optimum level so that oil
function will not be impaired. Therefore, it
is essential that the oil level be checked
regularly. Toyota recommends that the oil
level be checked every time you refuel
the vehicle.
NOTICE
Failure to check the oil level regularly
could lead to serious engine trouble
due to insufficient oil.
For detailed information on oil level check,
see “Checking the engine oil level” in Sec-
tion 7
−2.
Facts about engine oil
consumption

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Oil identification marks
Either or both API registered marks are
added to some oil containers to help
you select the oil you should use.
The API Service Symbol is located any-
where on the outside of the container.
The top portion of the label shows the oil
quality by API (American Petroleum Insti-
tute) designations such as SL. The center
portion of the label shows the SAE viscos-
ity grade such as SAE 5W−30. “Energy −
Conserving” shown in the lower portion,
indicates that the oil has fuel −saving ca-
pabilities.
The ILSAC (International Lubricant Stan-
dardization and Approval Committee) Certi-
fication Mark is displayed on the front of
the container.
To ensure excellent lubrication perfor-
mance for your engine, “Toyota Genuine
Motor Oil” is available, which has been
specifically tested and approved for all
Toyota engines.
Please contact your Toyota dealer for fur-
ther details about “Toyota Genuine Motor
Oil”. Look at the seethrough coolant reser-
voir when the engine is cold. The cool-
ant level is satisfactory if it is between
the “F” and “L” lines on the reservoir.
If the level is low, add ethyleneglycol
type coolant for a proper corrosion
protection of aluminum components.
The coolant level in the reservoir will vary
with engine temperature. However, if the
level is on or below the “L” line, add
coolant. Bring the level up to the “F” line.
Always use ethylene
−glycol type coolant
for a proper corrosion protection of alumi-
num components. See information in the
next column.
If the coolant level drops within a short
time after replenishing, there may be a
leak in the system. Visually check the
radiator, hoses, radiator cap and drain
cock and water pump.
If you can find no leak, have your Toyota
dealer test the cap pressure and check
for leaks in the cooling system.
CAUTION
To prevent burning yourself, do not
remove the radiator cap when the en-
gine is hot.
Checking the engine coolant
level