coolant temperature TOYOTA MIRAI 2018 Owners Manual (in English)

832. Fuel cell vehicle
2
Fuel cell system
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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

882. Fuel cell vehicle
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Power output restriction
When the power output is restricted, the vehicle may fail to accelerate or even
decelerate, even though the accelerator pedal is depressed. If a safe driving
speed cannot be maintained, stop the vehicle in a safe place aw ay from the
traffic. This may be caused by the following conditions:
● The coolant temperature may be too high. This can be caused by driving
conditions such as repeated sudden acceleration and deceleratio n, continu-
ous driving on an incline, continuous driving at high altitudes with a high
load, etc. In such situations, the power output restriction ind icator (amber) is
displayed on the main display, “High FC Temperature Reduced Power” is
displayed on the multi-information display, and the power outpu t is
restricted. Once the coolant returns to normal temperature, the power out-
put will return to normal. ( P. 377)
● The remaining fuel may be low. After the low fuel warning indicator comes
on, the output power will be gradually restricted in order to extend the possi-
ble driving distance. Once getting to this point, the remaining driving dis-
tance possible is short. Immediately refill the vehicle with hy drogen.
● On cold days, the low fuel warning indicator comes on faster than usual and
the output power is restricted.
■ Vehicle proximity notification system
In the following cases, the vehicle proximity notification syst em may be diffi-
cult to hear for people around.
● In very noisy areas
● In wind or rain
Also, because the vehicle proximity notification system is loca ted in the front
of the vehicle, it may be more difficult to hear from the rear of the vehicle
compared to the front.
■ Electromagnetic waves (EMF)
●High-voltage parts and cables in fuel cell vehicles have an ele ctromagnetic
shielding configuration, and therefore emit approximately the s ame amount
of electromagnetic waves as conventional gasoline-powered vehicles or
home electronic appliances.
● Your vehicle may cause sound interference in some third party-p roduced
radio parts.
■ Traction battery
The traction battery has a limited service life. The lifespan of the traction bat-
tery can change according to driving style and driving conditio ns.

993. Instrument cluster
3
Instrument cluster
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Warning lights inform the driver of malfunctions in the indicated vehi-
cle’s systems.
Warning lights
*1
Hydrogen leak warning
light ( P. 369)*1
Slip indicator ( P. 370)
*1
Brake system warning
light (P. 369)Parking brake warning
light (P. 371)
*1
Charging system
warning light ( P. 369)Open door warning light
(P. 371)
*1High coolant
temperature warning
light ( P. 369)Low fuel level warning
light (P. 371)
*1
Brake system warning
light (P. 369)Driver’s and front
passenger’s seat belt
reminder light ( P. 3 7 1 )
*1
SRS warning light
(P. 370)*1
Master warning light
(P. 371)
*1
ABS warning light
(P. 370)*1
Tire pressure warning
light ( P. 371)
*1
(Red/
Ye l l o w )
Electric power steering
system warning light
( P. 370)*3Brake Override System/
Drive-Start Control
warning light ( P. 372)
*1, 2
PCS warning light
(P. 370)

1033. Instrument cluster
3
Instrument cluster
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Power restriction indicator
Blue: The fuel cell system output power is restricted, because the
coolant temperature is low.
Amber: The fuel cell system output power is restricted, because the
coolant temperature is high.
Outside temperature
Displays the outside temperature within the range of -40°F (-40 °C)
to 122°F (50°C).
Low outside temperature indicator flashes when the ambient tem-
perature is 37°F (3°C) or lower.
Driving range distance
Displays the estimated maximum distance that can be driven with
the quantity of fuel remaining. • Displays the possible driving d istance computed from the fuel
consumption studied f rom the driving history and the current
remaining amount of fuel. The ac tual possible driving distance
may differ as fuel consumpti on changes, depending on driving
environment (weather, traffic, etc.) and conditions (sudden acc el-
eration, air conditioning, etc.).
• When only a small amount of fuel is added to the hydrogen tanks, the display may not be updated.
Speedometer
Displays the vehicle speed.
Odometer and trip meter
Odometer:
Displays the total distance the vehicle has been driven.
Trip meter:
Displays the distance the vehicl e has been driven since the met er
was last reset.
Trip meters “A” and “B” can be used to record and display diffe rent
distances independently.
Distance after start:
Displays the distance driven afte r the fuel cell system was started.
Blank:
A blank is displayed.

1063. Instrument cluster
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Outside temperature display
●In the following situations, the correct outside temperature ma y not be dis-
played, or the display may take longer than normal to change.
• When stopped, or driving at low speeds (less than 16 mph [25 k m/h])
• When the outside temperature has changed suddenly (at the entr ance/
exit of a garage, tunnel, etc.)
● When “--” or “E” is displayed, the system may be malfunctioning .
Take your vehicle to your Toyota dealer.
■ Liquid crystal display
Small spots or light spots may appear on the display. This phen omenon is
characteristic of liquid crystal displays, and there is no prob lem continuing to
use the display.
■ Customization
The meter display can be customized on the multi-information di splay.
(Customizable features: P. 439)
NOTICE
■To prevent damage to the fuel cell system and its components
This vehicle is equipped with high coolant temperature warning light
(  P. 369), instead of, coolant temperature gauge.
The fuel cell system may be overheating if the high coolant temperature
warning light flashes or comes on. In this case, immediately st op the
vehicle in a safe place, and che ck the fuel cell system after it has cooled
completely.

3197-3. Do-it-yourself maintenance
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7
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.
● Take care because brake fluid can harm your hands or eyes and d amage
painted surfaces. If fluid gets on your hands or in your eyes, flush the
affected area with clean water immediately.
If you still experience discomfort, consult a doctor.
● 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. 325)
■ Safety glasses
Wear safety glasses to prevent flying or falling material, flui d 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.

3247-3. Do-it-yourself maintenance
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The coolant level is satisfactory if it is between the “FULL” a nd “LOW”
lines on the reservoir when the fuel cell system is cold.
“FULL” line
“LOW” line
If the level is on or below the
“LOW” line, contact your Toyota
dealer.
The coolant level is satisfact ory if it is between the “FULL” a nd “LOW”
lines on the reservoir when the fuel cell system is cold.
Inverter coolan t reservoir cap
“FULL” line
“LOW” line
If the level is on or below the
“LOW” line, add coolant up to the
“FULL” line.
■ Inverter coolant selection
Only use “Toyota Super Long Life Coolant” or a similar high quality ethylene
glycol based non-silicate, non-amine, non-nitrite, and non-bora te coolant with
long-life hybrid organic acid technology.
“Toyota Super Long Life Coolant” is a mixture of 50% coolant and 50% deion-
ized water. (Minimum temperature: -31 F [-35 C])
For more details about inverter coolant, contact your Toyota dealer.
Fuel cell stack coolant
NOTICE
■ Fuel cell stack coolant
An exclusive coolant for the fuel cell system is filled in the fuel cell stack
coolant reservoir. Do not use any substitute. It may damage you r vehicle.
Inverter coolant

3688-2. Steps to take in an emergency
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If you think something is wrong
●Fluid leaks un der the vehicle.
(Water dripping from the air conditioning a fter use is normal.)
● Flat-looking tires or uneven tire wear
● The high coolant temperature war ning light flashes or comes on
● Excessive tire squeal when cornering
● Strange noises related to the suspension system
● Pinging or other noises rel ated to the fuel cell system
● Stumbling or running roughly
● Appreciable loss of power
● Vehicle pulls heavily to one side when braking
● Vehicle pulls heavily to one s ide when driving on a level road
● Loss of brake effectiveness, spongy feeling, pedal almost touch es
the floor
If you notice any of the followi ng symptoms, your vehicle proba -
bly needs adjustment or repair. Contact your Toyota dealer as
soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms

3698-2. Steps to take in an emergency
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8
When trouble arises
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. 85
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. 406
 Immediately stop the vehicle in a safe place and con-
tact your Toyota dealer.
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.

4068-2. Steps to take in an emergency
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If your vehicle overheats
The following may indicate that your vehicle is overheating.
● The high coolant temperature warning light ( P. 369) 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. 376) 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