2020 TOYOTA MIRAI radiator

912. Fuel cell vehicle
2
Fuel cell system
MIRAI_OM_USA_OM62073U
The fuel cell vehicle has high-voltage components (about 650 V m axi-
mum) such as a fuel cell stack, traction battery, power control unit,
high-voltage cables (which are di stinguished from low-voltage cables
by their orange covers), electric motor (traction motor), etc., and high-
temperature parts such as the radiator for cooling. Pay attenti on to all
warning labels attached to the vehicle.
This diagram is for illustrative purposes only and may differ f rom the
actual vehicle.
High-voltage and high-temperature components
Warning label
Power control unit
High-voltage cables (orange)
Fuel cell stack
Traction battery
Service plug
Fuel cell converter Electric motor (traction motor)
Air conditioning compressor
Radiator for inverter cooling
Radiator for fuel cell stack
cooling
Auxiliary inverter
Cabin coolant heater

3617-2. Maintenance
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Maintenance and care
General maintenance
Listed below are the general maintenance items that should be
performed at the intervals specified in the “Owner’s Warranty
Information Booklet” or “Own er’s Manual Supplement/Sched-
uled Maintenance Guide”. It is recommended that any problem
you notice should be brought to the attention of your Toyota
dealer or qualified s ervice shop for advice.
Motor compartment
ItemsCheck points
Brake fluidIs the brake fluid at the correct
level? ( P. 372)
CoolantIs the coolant at the correct level?
(P. 370)
Radiator/condenser
The radiator and condenser should
be free from foreign objects.
(P. 371)
Washer fluidIs there sufficient washer fluid?
(P. 373)
Tr u nk
ItemsCheck points
12-volt battery Check the connections. (P. 374)

3647-3. Do-it-yourself maintenance
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Do-it-yourself ser vice precautions
If you perform maintenance by yourself, be sure to follow the
correct procedure as given in these sections.
ItemsParts and tools
12-volt battery
condition
(  P. 3 7 4 )•Grease
• Conventional wrench (for terminal clamp bolts)
Brake fluid level
( P. 3 7 2 )
• FMVSS No.116 DOT 3 or SAE J1703 brake fluid, or
FMVSS No.116 DOT 4 or SAE J1704 brake fluid
• Rag or paper towel
• Funnel (used only for adding brake fluid)
Inverter coolant
level ( P. 370)
• “Toyota Super Long Life Coolant” or a similar high
quality ethylene glycol-based non-silicate, non-
amine, non-nitrite and non-borate coolant with long-
life hybrid organic acid technology.
For the U.S.A.:
“Toyota Super Long Life Coolant” is pre-mixed with
50% coolant and 50% deionized water.
For Canada:
“Toyota Super Long Life Coolant” is pre-mixed with
55% coolant and 45% deionized water.
• Funnel (used only for adding coolant)
Fuses ( P. 402)• Fuse with same amperage rating as original
Light bulbs
( P. 4 0 5 )
Radiator and con-
denser (
P. 371)
Tire inflation
pressure
( P. 393)• Tire pressure gauge
• Compressed air source
Washer fluid
( P. 3 7 3 )• Water or washer fluid containing antifreeze (for win-
ter use)
• Funnel (used only for adding water or washer fluid)

3657-3. Do-it-yourself maintenance
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Maintenance and care
WARNING
The motor compartment contains many mechanisms and fluids that may
move suddenly, become hot, or become electrically energized. To avoid death
or serious injury, observe the following precautions.
■ When working on the motor compartment
● Be careful not to touch the high-voltage parts or hydrogen-rela ted parts.
● Make sure that the “READY” indicator is off.
● Keep hands, clothing and tools away from the moving fans.
● Be careful not to touch the motor, inverter, radiator, etc., ri ght after driving
as they may be hot. Coolant and other fluids may also be hot.
● Do not leave anything that may burn easily, such as paper and r ags, in the
motor compartment.
● Do not smoke, cause sparks or expose an open flame to the 12-volt bat-
tery. 12-volt battery fumes are flammable.
● Be extremely cautious when working on the 12-volt battery. It c ontains poi-
sonous and corrosive sulfuric acid.
● Never touch, disassemble, remove or replace the high-voltage parts,
cables and their connectors. It can cause severe burns or electric shock
that may result in death or serious injury.
■ When working near the electric cooling fans or radiator grille
Be sure the power switch is off.
With the power switch in ON mode, the electric cooling fans may automati-
cally start to run if the air conditioning is on and/or the coolant temperature
is high. ( P. 371)
■ Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc.,
from getting in your eyes.
NOTICE
■If you remove the air cleaner filter
Driving with the air cleaner filter removed may cause excessive motor wear
due to dirt in the air.

3697-3. Do-it-yourself maintenance
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Maintenance and care
Motor compartment
Washer fluid tank (P. 373)
Brake fluid reservoir ( P. 372)
Inverter coolant reservoir ( P. 370)
Fuse box ( P. 402)
Fuel cell stack coolant radiator
( P. 371) Inverter coolant radiator
( P. 371)
Condenser ( P. 371)
Electric cooling fans
Fuel cell stack coolant reser-
voir ( P. 370)
Fuel cell stack coolant sub
radiator ( P. 371)

3717-3. Do-it-yourself maintenance
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Maintenance and care
■If the inverter coolant level drops within a short time of repl enishing
Visually check the radiators, hoses, inverter coolant reservoir cap, drain cock
and water pump.
If you cannot find a leak, have your Toyota dealer test the cap and check for
leaks in the cooling system.
Check the radiator and condenser and clear away any foreign objects.
If either of the above parts is extremely dirty or you are not sure of
their condition, have your vehic le inspected by your Toyota dea ler.
WARNING
■When the fuel cell system is hot
Do not remove the coolant reservoir caps.
The cooling system may be under pressure and may spray hot coolant if the
cap is removed, causing serious injuries, such as burns.
NOTICE
■When adding coolant
Coolant is neither plain water nor straight antifreeze. The cor rect mixture of
water and antifreeze must be used to provide proper lubrication , corrosion
protection and cooling. Be sure to read the antifreeze or coolant label.
■ If you spill coolant
Be sure to wash it off with water to prevent it from damaging p arts or paint.
Radiator and condenser
WARNING
■When the fuel cell system is hot
Do not touch the radiator or condenser as they may be hot and c ause seri-
ous injuries, such as burns.

4588-2. Steps to take in an emergency
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If the high coolant temperature warning light comes on or
flashes
Stop the vehicle in a safe place and turn off the air condition
ing sys-
tem, and then stop t he fuel cell system.
If you see steam or coolant leaks:
Carefully lift the hood after the steam subsides.
If you do not see steam or coolant leaks:
Carefully lift the hood.
After the fuel cell system has
cooled down sufficiently,
inspect the hoses and radiator
core (radiator) for any leaks.
Fuel cell stack coolant sub
radiator
Fuel cell stack coolant radia-
tor
Electric cooling fans
If a large amount of coolant leaks, immediately contact your Toyota
dealer.
NOTICE
Correction procedures
The fuel cell stack coolant is exclusive for
fuel cell stack usage. Damage may occur
when water or any other type of coolant
is used, so never use any other fluid.
If the fuel cell stack coolant is low, imme-
diately contact your Toyota dealer.
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4608-2. Steps to take in an emergency
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If “FC System Overheat Output P
ower is Limited” is displayed
on the multi-information display
Stop the vehicle in a safe place and turn off the air conditioning
system, and then stop th e fuel cell system.
If you see steam or coolant leaks:
Carefully lift the hood after the steam subsides.
If you do not see steam or coolant leaks:
Carefully lift the hood.
After the fuel cell system has
cooled down, inspect the
hoses and radiator core
(radiator) for any leaks.
Inverter coolant radiator
Electric cooling fans
If a large amount of coolant
leaks, immediately contact
your Toyota dealer.
The inverter coolant level is
satisfactory if it is between
the “FULL” and “LOW” lines
on the reservoir.Inverter coolant reservoir
“FULL”
“LOW”
Add inverter cool ant if neces-
sary.
Water can be used in an emer-
gency if inverter coolant is
unavailable.
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