2022 TOYOTA MIRAI cooling

4237-3. Do-it-yourself maintenance
Owners Manual_USA_M62084_en
7
Maintenance and care
■If the electronic key battery is
depleted
The following symptoms may occur:
●The smart key system and wire-
less remote control will not func-
tion properly.
●The operational range will be
reduced.
 Flathead screwdriver
 Small flathead screwdriver
 Lithium battery CR2032
■Use a CR2032 lithium battery
●Batteries can be purchased at
your Toyota dealer, local electrical
appliance shops or camera stores.
●Replace only with the same or
equivalent type recommended by
the manufacturer.
●Dispose of used batteries accord-
ing to local laws.
NOTICE
■If “Maintenance Required for
Traction Battery Cooling
Parts See Owner’s Manual” is
shown on the multi-informa-
tion display
If the vehicle is continuously
driven with the warning message
(indicating that charging/discharg-
ing of the traction battery may
become limited) displayed, the
traction battery may malfunction.
If the warning message is dis-
played, clean the air intake vents
immediately.
Electronic key batter y
Replace the battery with a
new one if it is depleted.
As the key may be damaged
if the following procedure is
not performed properly, it is
recommended that key bat-
tery replacement be per-
formed by your Toyota
dealer.
Items to prepare

4548-2. Steps to take in an emergency
Owners Manual_USA_M62084_enabout 6 seconds): Maintain the
fuel cell system operation for more
than 15 minutes and charge the
12-volt battery.
• When the display does not go off: Start up the fuel cell system using
the procedures: P.471
●If “Maintenance Required for Trac-
tion Battery Cooling Parts See
Owner’s Manual” is shown, the fil-
ters may be clogged, the air intake
vents may be blocked, or there
may be a gap in the duct. There-
fore, perform the following correc-
tion procedure.
• If the air intake vents and filters of the traction batte ry are dirty, per-
form the procedure on P.420 to
clean them.
• If the warning message is shown
when the air intake vents and fil-
ters of the traction battery are not
dirty, have the vehicle inspected
by your Toyota dealer.
■If “Ion Filter Maintenance
Required Visit Your Dealer” is
displayed
Ion filter replacement is necessary.
Contact your Toyota dealer.
NOTICE
■If “Low Auxiliary Battery See
Owner’s Manual” is displayed
frequently
The 12-volt battery may have
deteriorated. As the battery may
discharge in this state when left
unattended, have the battery
inspected by your Toyota dealer.
■If “Maintenance Required For
Traction Battery At Your
Dealer” is displayed
This message indicates that the
traction battery may require
inspection or replacement. Have
the vehicle inspected by your Toy-
ota dealer immediately.
Do not continue driving the vehi-
cle, as the fuel cell system may
become not able to be started
again.

4758-2. Steps to take in an emergency
Owners Manual_USA_M62084_en
8
When trouble arises
WARNING
●When working with the 12-volt
battery, always wear safety
glasses and take care not to
allow any battery fluids (acid) to
come into contact with skin,
clothing or the vehicle body.
●Do not lean over the 12-volt bat-
tery.
●In the event that battery fluid
comes into contact with the skin
or eyes, immediately wash the
affected area with water and
seek medical attention. Place a
wet sponge or cloth over the
affected area until medical
attention can be received.
●Always wash your hands after
handling the 12-volt battery sup-
port, terminals, and other bat-
tery-related parts.
●Do not allow child ren near the
12-volt battery.
■After recharging the 12-volt
battery
Have the 12-volt battery
inspected at your Toyota dealer
as soon as possible.
If the 12-volt battery is deteriorat-
ing, continued use may cause the
12-volt battery to emit a malodor-
ous gas, which may be detrimen-
tal to the health of passengers.
■When replacing the 12-volt
battery
●When the vent plug and indica-
tor are close to the hold down
clamp, the battery fluid (sulfuric
acid) may leak.
●For information regarding 12-
volt battery rep lacement, con-
tact your Toyota dealer.
●After replacing, s ecurely attach
the exhaust hose and exhaust
hole plug to the exhaust hole of
the replaced 12-volt battery. If
not properly installed, gases
(hydrogen) may leak into the
vehicle interior, and there is the
possible danger of the gas ignit-
ing and exploding.
NOTICE
■When handling jumper cables
When connecting the jumper
cables, ensure that they do not
become entangled in the cooling
fan.
■To prevent damaging the
vehicle
The exclusive jump starting termi-
nal is to be used when charging
the 12-volt battery from another
vehicle in an emergency. It cannot
be used to jump start another
vehicle.

4768-2. Steps to take in an emergency
Owners Manual_USA_M62084_en
Label
Fuel cell stack coolant reservoir
Inverter coolant reservoir
If your vehicle overheats
The following may indicate that your vehicle is overheating.
The high coolant temperature warning light ( P.442) comes on
or flashes, or a loss of fuel cell system power is experienced.
(For example, the vehicle speed does not increase.)
 The fuel cell system overheat warning light ( P.442) comes on
 Steam comes out from under the hood.
Parts name for cooling components

4778-2. Steps to take in an emergency
Owners Manual_USA_M62084_en
8
When trouble arises
If the high coolant tempera-
ture warning light comes on or
flashes
1 Stop the vehicle in a safe
place and turn off the air con-
ditioning system, and then
stop the fuel cell system.
2 If you see steam:
Carefully lift the hood after
the steam subsides.
If you do not see steam:
Carefully lift the hood.
3 After the fuel cell system has
cooled down sufficiently,
inspect the hoses and radia- tor core (radiator) for any
leaks.
Electric cooling fan
Fuel cell stack coolant radia-
tor
If a large amount of coolant leaks,
immediately contact your Toyota
dealer.
4
The fuel cell stack coolant
level is satisfactory if it is
between the “MAX” and
“MIN” lines on the reservoir.
Fuel cell stack coolant reser-
voir
“MAX” line
“MIN” line
If the amount of fuel cell stack
coolant is low:
Immediately contact your Toyota
dealer.
NOTICE
■Fuel cell stack coolant
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, immediately contact your
Toyota dealer.
Correction procedures

4788-2. Steps to take in an emergency
Owners Manual_USA_M62084_en
If the amount of fuel cell stack
coolant is not low:
Have the vehicle inspected at
the nearest Toyota dealer.
Even if the fuel cell stack cool-
ant is low, do not refill it.
If the fuel cell system over-
heat warning light comes on
1 Stop the vehicle in a safe
place and turn off the air con-
ditioning system, and then
stop the fuel cell system.
2 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.
3 After the fuel cell system has
cooled down, inspect the hoses and radiator core (radi-
ator) for any leaks.
Electric cooling fan
Inverter coolant radiator
If a large amount of coolant leaks,
immediately contact your Toyota
dealer.
4
The inverter coolant level is
satisfactory if it is between
the “MAX” and “MIN” lines on
the reservoir.
Inverter coolant reservoir
“MAX” line
“MIN” line
5 Add inverter coolant if neces-
sary.
Water can be used in an emer-
gency if inverter coolant is unavail-

4798-2. Steps to take in an emergency
Owners Manual_USA_M62084_en
8
When trouble arises
able.
6 Start the fuel cell system and
turn the air conditioning sys-
tem on to check that the radi-
ator cooling fan operate and
to check for coolant leaks
from the radiator or hoses.
The fan operate when the air condi-
tioning system is turned on immedi-
ately after a cold s tart. Confirm that
the fan is operating by checking the
fan sound and air flow. If it is diffi-
cult to check these, turn the air con-
ditioning system on and off
repeatedly.
(The fan may not o perate in freez-
ing temperatures.)
7 If the fan is not operating:
Stop the fuel cell system
immediately and contact your
Toyota dealer.
If the fan is operating:
Have the vehicle inspected at
the nearest Toyota dealer.
WARNING
■When inspecting under the
hood of your vehicle
Observe the following precau-
tions.
Failure to do so may result in seri-
ous injury such as burns.
●If steam is seen coming from
under the hood, do not open the
hood until the steam has sub-
sided. The fuel cell unit com-
partment may be very hot.
●Even if fuel cell system has
stopped, the cooling fan may
begin to move suddenly.
Do not touch or approach the
rotating parts of the fan. Doing
so may lead to fingers, clothes
or tools getting caught, resulting
in injury.
●Do not loosen the coolant reser-
voir caps or radia tor cap, while
the fuel cell system and radiator
are hot.
High temperature steam or
coolant could spray out.
NOTICE
■When inverter coolant
Add coolant slowly after the fuel
cell system has cooled down suffi-
ciently. Adding inverter cool cool-
ant to a hot fuel cell system too
quickly can cause damage to the
fuel cell system.
■To prevent damage to the
cooling system
Observe the following precau-
tions:
●Avoid contaminating the coolant
with foreign matter (such as
sand or dust etc.).
●Do not use any coolant additive
with inverter coolant.
●For replacement of the fuel cell
stack coolant, contact your Toy-
ota dealer.
●Do not use water or any other
coolant when refilling the fuel
cell stack coolant. Also, do not
use any additive agents for the
coolant.

4849-1. Specifications
Owners Manual_USA_M62084_en
Electric motor (traction motor)
Ty p ePermanent magnet synchronous
motor
Maximum output134 kW
Maximum torque221.3 ft•lbf (300 N•m, 30.6 kgf•m)
Traction battery
Ty p eLithium-ion battery
Voltage3.7 V/cell
Capacity4.0 Ah
Quantity84 cells
Nominal voltage310.8 V
Cooling system
Capacity*
Fuel cell
stack17.3 qt. (16.4 L, 14.4 Imp. qt.)
Inverter4.2 qt. (4.0 L, 3.5 Imp. qt.)