2020 TOYOTA MIRAI coolant temperature

4188-2. Steps to take in an emergency
MIRAI_OM_USA_OM62073U
If a warning light turns on or a war ning
buzzer sounds
Calmly perform the following actions if any of the warning ligh ts
comes on or flashes. If a light comes on or flashes, but then
goes off, this does not necessarily indicate a malfunction in the
system. However, if this continues to occur, have the vehicle
inspected by your Toyota dealer.
Warning light and w arning buzzer list
Warning lightWarning light/Details/Actions
Hydrogen leak warning light (warning buzzer)
When a hydrogen gas leak is detected, a buzzer sounds,
a light comes on, and a warning message is displayed on
the multi-information display.
 P. 93
(U.S.A.)
(Red)
(Canada)
Brake system warning li ght (warning buzzer)*1
Indicates that:
• The brake fluid level is low; or
• The brake system is malfunctioning
 Immediately stop the vehicle in a safe place and con-
tact your Toyota dealer. Continuing to drive the vehi-
cle may be dangerous.
Charging system warning light
Indicates a malfunction in the vehicle’s charging system
 Immediately stop the vehicle in a safe place and con-
tact your Toyota dealer.
High coolant temperature warning light
Indicates that the coolant temperature is abnormal
P. 457
 Immediately stop the vehicle in a safe place and con-
tact your Toyota dealer.
(Yellow)
Brake system warning light
Indicates a malfunction in:
• The regenerative braking system; or
• The electronically controlled brake system
 Have the vehicle inspected by your Toyota dealer
immediately.

4578-2. Steps to take in an emergency
MIRAI_OM_USA_OM62073U
8
When trouble arises
If your vehicle overheats
The following may indicate that your vehicle is overheating.
● The high coolant temperature warning light ( P. 418) comes on
or flashes, or a loss of fuel ce ll system power is experienced. (For
example, the vehicle s peed does not increase.)
● “FC System Overheat Output Power is Limited” ( P. 426) is dis-
played on the multi-in formation display
● Steam comes out from under the hood.
Label
Fuel cell stack coolant
reservoir Inverter coolant reservoir

4588-2. Steps to take in an emergency
MIRAI_OM_USA_OM62073U■
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.
1
2
3

4618-2. Steps to take in an emergency
MIRAI_OM_USA_OM62073U
8
When trouble arises
Start the fuel cell system and turn the air conditioning system on
to check that the radiator coo ling fans operate and to check fo r
coolant leaks from t he radiator or hoses.
The fans operate when the air conditioning system is turned on immedi-
ately after a cold start. Confirm that the fans are operating b y checking
the fan sound and air flow. If it is difficult to check these, turn the air con-
ditioning system on and off repeatedly.
(The fans may not operate in freezing temperatures.)
If the fans are not operating:
Stop the fuel cell system immed iately and contact your Toyota
dealer.
If the fans are operating:
Have the vehicle inspected at the neare st Toyota dealer.
WARNING
■When inspecting under th e hood of your vehicle
Observe the following precautions.
Failure to do so may result in serious injury such as burns.
● If steam is seen coming from under the hood, do not open the ho od until
the steam has subsided. The motor compartment may be very hot.
● After the fuel cell system has been turned off, check that the “READY”
indicator is off.
When the fuel cell system is operating, the cooling fans may suddenly
operate even if the fuel cell system stops. Do not touch or app roach rotat-
ing parts such as the fans, which may lead to fingers or clothing (espe-
cially a tie, a scarf or a muffler) getting caught, resulting i n serious injury.
● Do not loosen the coolant reservoir caps or radiator cap, while the fuel cell
system and radiator are hot.
High temperature steam or coolant could spray out.
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518Alphabetical index
MIRAI_OM_USA_OM62073U
Fuel cell stack ............................ 94
Fuel cell stack coolantCapacity ................................ 469
Checking ............................... 370
Fuel cell system
Characteristics ........................ 86
Cold temperatures ................ 189
Coolant type.......................... 469
Indicators .............................. 109
Multi-information display ....... 117
Precautions ............................. 90
Starting the system ............... 186
Stopping the system ............. 187
Warning lights ....................... 107
Fuel cell system indicator....... 120
Fuel cell vehicles Characteristics ........................ 86
Charging the traction
battery .................................. 89
Driving advice ....................... 102
Emergency shut off system .... 92
Emergency start function ...... 448
Emergency stops .................. 409
Fuel ....................................... 468
Handling hydrogen gas ........... 98
High-voltage components ....... 91
Hydrogen gas ......................... 97
Hydrogen-related
components .......................... 90
If the 12-volt battery is
discharged .......................... 452
If the fuel cell system will not start .................................... 447
Maintenance, repair, recycling, and disposal ......... 89 Opening the fuel door ........... 213
Overheating .......................... 457
Power output restriction .......... 96
Power switch ........................ 186
Precautions............................. 90
Regenerative braking ............. 89
Road accident cautions ........ 100
Running out of fuel ................. 93
Service plugs .......................... 99
Sounds and vibrations ............ 88
Starting the system ............... 186
Traction battery air intake
vent ...................................... 93
Vehicle proximity notification
system .......... ..................... ... 92
Warning message................. 426
Water release ....................... 187
Fuel consumption ........... 121, 122
Fuel door .................................. 213 Refueling .............................. 213
Fuses ........................................ 402
Garage door opener ................ 343
Gauges ..................................... 111
Glove box ................................. 321
Grocery bag hooks.................. 325
G

527Alphabetical index
MIRAI_OM_USA_OM62073U
Warning buzzersBrake system ....... ................. 418
Electric power steering system ......... ....................... 419
Intuitive parking assist .......... 269
Light reminder ....................... 204
Open door ............................. 420
Open trunk ............................ 420
Parking brake........................ 200
Parking Support Brake function
(for static objects) .............. 419
Seat belt reminder ................ 421
Warning lights
ABS....................................... 419
Brake Override System......... 421
Brake system ....... ................. 418
Charging system ................... 418
Drive-Start Control ................ 421
Electric power steering system ......... ....................... 419
High coolant temperature warning light ....................... 418
Hydrogen leak....................... 418
Low fuel level ........................ 420
Master warning light.............. 421
Parking brake........................ 420
Parking Support Brake function
(for static objects) ............... 419
Pre-collision syst em .............. 420
Seat belt reminder light ......... 421
Slip indicator ......................... 420
SRS ...................................... 419
Tire pressure......................... 421 Warning messages.................. 426
Washer ..................................... 210
Checking............................... 373
Preparing and checking before winter ...................... 301
Switch ................................... 210
Washing and waxing ............... 352
Water release ........................... 187
Weight ...................................... 466 Cargo capacity...................... 183
Load limits ............................ 183
Vehicle capacity weight ........ 466
Wheels ...................................... 396 Replacing.............................. 396
Size....................................... 471
Window glasses ...................... 167
Window lock switch ................ 167
Windows................................... 167 Power windows..................... 167
Rear window defogger.......... 309
Windshield wipers ................... 210
Winter driving tips ................... 301
Wireless remote control ......... 128 Battery-Saving Function ....... 145
Locking/Unlocking ................ 132
Replacing the battery............ 400
WMA disc
*
W
*: Refer to the “NAVIGATION SYSTEM OWNER’S MANUAL”.