2017 TOYOTA MIRAI fuel system

271-1. For safe use
1
For safety and security
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WARNING
Observe the following precautions.
Failure to do so may cause the driver’s floor mat to slip, possibly interfering
with the pedals while driving. An unexpectedly high speed may result or it may
become difficult to stop the vehicle. This could lead to an accident, resulting in
death or serious injury.
■When installing the driver’s floor mat
● Do not use floor mats designed for other models or different model year
vehicles, even if they are Toyota Genuine floor mats.
● Only use floor mats designed for the driver’s seat.
● Always install the floor mat securely using the retaining hooks (clips) pro-
vided.
● Do not use two or more floor mats on top of each other.
● Do not place the floor mat bottom-side up or upside-down.
■ Before driving
● Check that the floor mat is securely
fixed in the correct place with all the
provided retaining hooks (clips). Be
especially careful to perform this check
after cleaning the floor.
● With the fuel cell system stopped and
the shift position in P, fully depress each
pedal to the floor to make sure it does
not interfere with the floor mat.

721-2. Theft deterrent system
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Immobilizer system
The indicator flashes after the
power switch has been turned off
to indicate that the system is oper-
ating.
The indicator stops flashing after
the power switch has been turned
to ACCESSORY or ON mode to
indicate that the system has been
canceled.
The vehicle’s keys have built-in transponder chips that prevent
the fuel cell system from starting if a key has not been previ-
ously registered in the vehicle’s on-board computer.
Never leave the keys inside the vehicle when you leave the vehi-
cle.
This system is designed to help prevent vehicle theft but does
not guarantee absolute security against all vehicle thefts.

741-2. Theft deterrent system
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Alarm
The alarm uses light and sound to give an alert when an intrusion is
detected.
The alarm is triggered in the following situations when the alarm is
set:
●A locked door or trunk is unlocked or opened in any way other than
using the entry function, wireless remote control or mechanical key.
(The doors will lock again automatically.)
● The hood is opened.
Close the doors, trunk and hood,
and lock all the doors. The system
will be set automatically after 30
seconds.
The indicator changes from being
on to flashing when the system is
set.
Do one of the following to deactivate or stop the alarm:
● Unlock the doors or open the trunk.
● Turn the power switch to ACCESSORY or ON mode, or start the
fuel cell system. (The alarm will be deactivated or stopped after a
few seconds.)
The alarm
Setting the alarm system
Deactivating or stopping the alarm

77
Fuel cell system2
MIRAI_OM_USA_OM62023U2. Fuel cell vehicle
Fuel cell vehicle characteristics ................... 78
Fuel cell vehicle precautions ....................... 82
Advice for driving fuel cell vehicles ............................. 94

792. Fuel cell vehicle
2
Fuel cell system
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The electric motor (traction motor) allows smooth, powerful takeoff
and acceleration. This vehicle drives similarly to a gasoline vehicle
without any special actions by the driver. ( →P. 158) As there are no
engine sounds and the vehicle is qu iet, operation noises unique to
fuel cell vehicle components may be heard. ( →P. 8 0 )
The system may behave differently on cold days. It is performing a
special cold-start process to im prove start-up performance. (→P. 175)
Operation noises (→ P. 80), purge process ( →P. 175), etc., differ from
usual. However, this is not a malfunction.
Compressed hydrogen gas fuel can be filled at hydrogen stations.
Opening the fuel door ( →P. 198)
Driving the vehicle
Fuel cell system
Fuel filling

802. Fuel cell vehicle
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■Sounds unique to the fuel cell vehicle
Due to the design of your fuel cell vehicle, there are various relays, valves
and pumps which under normal driving conditions will produce sounds. This
is a normal characteristic of the vehicle and does not indicate a malfunction.
Furthermore, way of hearing may differ based on usage environment or con-
dition.
Noticeable soundsSource of the sounds
Clunking, clicking and clack-
ingOperation of relays and hydrogen tank
valves
Sounds may come from under the floor or
behind the rear seats.
(Sounds may be heard when starting the
fuel cell system.)
KnockingThe parking lock is engaged
Sounds may come from the motor
compartment.
(Sounds may be heard when press the P
position switch or stopping the fuel cell
system.)
Whooshing, squealingGas is flowing through the nozzle and
valvesSounds may come from behind the rear
seats, or from the dispenser hose/nozzle.
(Sounds may be heard when filling the
fuel.)
• High pitch sound
• Gurgle sound
• Pulsing soundOperation of the pumpsSounds may come from the motor com-
partment or under the front seats.
(In particular, sounds may be heard when
starting the fuel cell system, accelerating
from a stop, or press the H
2O switch. The
sound may be louder when in Br mode or
when the vehicle decelerates during
dynamic radar cruise control.)
Humming soundOperation of the pumps are speeding up
Sounds may come from the motor com-
partment or under the front seats.
(In particular, sounds may be heard when
accelerating or decelerating.)
Whooshing sound Operation of the hydrogen injectorSounds may come from under the front
seats or behind the rear seats.
(In particular, sounds may be heard when
starting the fuel cell system, driving at low
speeds, or charging the traction battery.)

812. Fuel cell vehicle
2
Fuel cell system
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Regenerative braking
In the following situations, the vehicle generates electricity from the decelera-
tion of the vehicle while driving.
●The accelerator pedal is released while driving with the shift position in D.
● The brake pedal is depressed while driving with the shift position in D.
■ Charging the traction battery
Because electricity generated by the fuel cell stack and regenerative braking
charges the traction battery, the battery does not need to be charged from an
outside source. However, if the vehicle is left parked for a long time, the trac-
tion battery will slowly discharge. For this reason, be sure to drive the vehicle
at least once every few months for at least 30 minutes or 10 miles (16 km).
If the traction battery becomes fully discharged and you are unable to start
the fuel cell system, contact your Toyota dealer.
■ Charging the 12-volt battery
→P. 403
■ Parking
Because there is no engine sound or vibration, it is easy to mistake the fuel
cell vehicle for being off when it is actually still running, as indicated by the
“READY” indicator being illuminated. For safety, make sure to always shift the
shift position to P and apply the parking brake when parked.
■ Maintenance, repair, recycling, and disposal
Contact your Toyota dealer regarding maintenance, repair, recycling, and dis-
posal. Do not dispose of the vehicle or any of its components yourself.
• Humming sound
• High pitch soundOperation of the motor
Sounds may come from the motor com-
partment.
(In particular, sounds may be heard when
accelerating or decelerating.)
Blowing and draining soundExhaust water or air is being purgedSounds may come from the rear of the
vehicle.
May also occur periodically while parked
when it is cold to prevent freezing.
(Sounds may be heard when vehicle is
stopped, fuel cell system is stopped, park-
ing.)
Noticeable soundsSource of the sounds

832. Fuel cell vehicle
2
Fuel cell system
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The fuel cell vehicle has high-voltage components (about 650 V maxi-
mum) such as a fuel cell stack, traction battery, power control unit,
high-voltage cables (which are distinguished from low-voltage cables
by their orange covers), electric motor (traction motor), etc., and high-
temperature parts such as the radiator for cooling. Pay attention to all
warning labels attached to the vehicle.
This diagram is for illust rative purposes only and may differ from 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