TOYOTA MIRAI 2023 Owners Manual

4818-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
8
When trouble arises
 The 12-volt battery may be
discharged. ( P.485)
Contact your Toyot a dealer if the
problem cannot be repaired, or if
repair procedures are unknown.
When the fuel cell system does
not start, the following steps can
be used as an interim measure
to start the fuel cell system if the
power switch is functioning nor-
mally.
Do not use this starting proce-
dure except in cases of emer-
gency.
1 Pull the parking brake switch
to check that the parking
brake is set. ( P.191)
Parking brake indicator will come
on.
2 Turn the power switch to
ACC.
3 Press and hold the power
switch for about 15 seconds
while depressing the brake
pedal firmly.
Even if the fuel cell system can
be started using the above
steps, the system may be mal-
functioning. Have the vehicle
inspected by your Toyota dealer.
Starting the fuel cell sys-
tem in an emergency
If you lose your keys
New genuine mechanical
keys can be made by your
Toyota dealer using another
mechanical key and the key
number stamped on your
key number plate.
Keep the plate in a safe
place such as your wallet,
not in the vehicle.
NOTICE
■When an electronic key is lost
If the electronic key remains lost,
the risk of vehicle theft increases
significantly. Visit your Toyota
dealer immediately with all
remaining electronic keys that
were provided with your vehicle.

4828-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
1Remove the cover inside the
trunk.
2 After removing the cover, pull
the lever to unlock the fuel
door and it will be ready to
open as usual.
■When the electronic key does
not work properly
●Make sure that the smart key sys-
tem has not been deactivated in
the customization setting. If it is
off, turn the function on.
●Check if battery-saving mode is
set. If it is set, cancel the function.
( P.137)
If the fuel door cannot
be opened
If the fuel door opener
switch cannot be operated,
the following procedure can
be used to open the fuel
door.
Opening the fuel door
If the electronic key
does not operate prop-
erly
If communication between
the electronic key and vehi-
cle is interrupted ( P.138)
or the electronic key cannot
be used because the battery
is depleted, the smart key
system and wireless remote
control cannot be used. In
such cases, the doors and
trunk can be opened and
the fuel cell system can be
started by following the pro-
cedure below.
NOTICE
■In case of a smart key system
malfunction or other key-
related problems
Take your vehicle with all the elec-
tronic keys provided with your
vehicle to your Toyota dealer.

4838-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
8
When trouble arises
■Locking and unlocking the
door
Use the mechanical key
( P.126) in order to perform the
following operations:
1 Locks all the doors
2 Unlocks all the doors
■Locking the door
1 With the door open, push
down the inside lock button.
2 Close the door.
■Trunk
Turn the mechanical key clock-
wise to open. ( P.72)
■Key linked functions
1 Closes the windows (turn and
hold)
2 Opens the windows (turn and
hold)
These settings mus t be customized
at your Toyota dealer.
Locking and unlocking
the doors, unlocking the
trunk
WARNING
■When using the mechanical
key and operating the power
windows
Operate the power window after
checking to make sure that there
is no possibility of any passenger
having any of their body parts
caught in the window.
Also, do not allo w children to
operate the mechanical key. It is
possible for children and other
passengers to get caught in the
power window.

4848-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
1With the P shift position
selected, firmly depress the
brake pedal.
2 Touch the Toyota emblem
side of the electronic key to
the power switch.
When the electronic key is
detected, a buzzer sounds and the
power switch will turn to ON.
When the smart key system is
deactivated in customization set-
ting, the power switch will turn to
ACC.
3Firmly depress the brake
pedal and check that is
shown on the multi-informa-
tion display.
4 Press the power switch.
In the event that the fuel cell
system still cannot be started,
contact your Toyota dealer.
■Stopping the fuel cell system
Set the parking brake, shift the shift
position to P and press the power
switch as you no rmally do when
stopping the fuel cell system.
■Electronic key battery
As the above proce dure is a tempo-
rary measure, it is recommended
that the electronic key battery be
replaced immediatel y when the bat-
tery is depleted. ( P.436)
■Alarm (For Canada)
Using the mechanical key to lock
the doors will not set the alarm sys-
tem. If a door is unlocked using the
mechanical key when the alarm sys-
tem is set, the alarm may be trig-
gered. ( P.71)
■Changing power switch modes
Release the brake pedal and press
the power switch in step 3 above.
The fuel cell system does not start
and modes will be changed each
time the switch is pressed. ( P.183)
Starting the fuel cell sys-
tem

4858-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
8
When trouble arises
If you have a set of jumper (or
booster) cables and a second
vehicle with a 12-volt battery,
you can jump start your vehicle
by following the steps below.
1 Confirm that the electronic
key is being carried.
When connecting the jumper (or
booster) cables, depending on the
situation, the ala rm may activate and doors locked. (
P. 7 2 )
2 Open the hood. Remove the
fuse box cover. ( P.406)
Push the tabs in and lift the lid off.
3 Open the exclusive jump
starting terminal cover.
4 Connect a positive jumper cabl e clamp to on your vehicle and
connect the clamp on the other end of the positive cable to on
the second vehicle. Then, connect a negative cable clamp to
on the second vehicle and connect the clamp at the other end of
the negative cable to .
If the 12-volt batter y is
discharged
The following procedures
may be used to start the fuel
cell system if the 12-volt
battery is discharged.
You can also call your Toy-
ota dealer or a qualified
repair shop.
Restarting the fuel cell
system

4868-2. Steps to take in an emergency
Owners Manual_USA_M62064_enWhen connecting to an unpaint
ed metallic point , make the connection
after checking the surrounding a rea. Also, do not make any connections
where parts nearby may interfere.
Use jumper cables that can reach the specified terminals and connecting
point.
Exclusive jump starting terminal (your vehicle)
Positive (+) battery terminal (second vehicle)
Negative (-) battery term inal (second vehicle)
Metallic point shown in the illustration
5 Start the engine of the sec-
ond vehicle. Increase the
engine speed slightly and
maintain at that level for
approximately 5 minutes to
recharge the 12-volt battery
of your vehicle.
6 Open and close any of the
doors of your vehicle with the
power switch off.
7 Maintain the engine speed of
the second vehicle and start
the fuel cell system of your
vehicle by turning the power
switch to ON. 8
Make sure the “READY” indi-
cator comes on. If the indica-
tor does not come on, contact
your Toyota dealer.
9 Once the fuel cell system has
started, remove the jumper
cables in the exact reverse
order from which they were
connected.
10Close the exclusive jump starting terminal cover and
install the fuse box cover.
Once the fuel cell system starts,
have the vehicle inspected at
your Toyota dealer as soon as
possible.

4878-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
8
When trouble arises
■Starting the fuel cell system
when the 12-volt battery is dis-
charged
The fuel cell system cannot be
started by push-starting.
■To prevent 12-volt battery dis-
charge
●Turn off the headlights and the
audio system while the fuel cell
system is off.
●Turn off any unnecessary electri-
cal components when the vehicle
is running at a low speed for an
extended period, such as in heavy
traffic.
■When the 12-volt battery is
removed or discharged
●Information stor ed in the ECU is
cleared. When the 12-volt battery
is depleted, have the vehicle
inspected at you r Toyota dealer.
●Some systems may require initial-
ization. ( P.526)
●If the 12-volt battery discharges, it
may not be possible to shift the
shift position to other positions.
In this case, the vehicle cannot be
towed without lifting both rear
wheels because the rear wheels will
be locked.
■When removing the 12-volt bat-
tery terminals
When the 12-volt battery terminals
are removed, the information stored
in the ECU is cleared. Before
removing the 12-volt battery termi-
nals, contact your Toyota dealer.
■Charging the 1 2-volt battery
The electricity stor ed in the 12-volt
battery will discharge gradually even
when the vehicle is not in use, due
to natural discharge and the drain-
ing effects of certain electrical appli-
ances. If the vehicle is left for a long
time, the 12-volt battery may dis-
charge, and the fuel cell system
may be unable to s tart. (The 12-volt battery recharges automatically
while the fuel cell
system is operat-
ing.)
■When recharging or replacing
the 12-volt battery
●In some cases, it may not be pos-
sible to unlock the doors using the
smart key system when the 12-
volt battery is discharged. Use the
wireless remote c ontrol or the
mechanical key to lock or unlock
the doors.
●The fuel cell system may not start
on the first attempt after the 12-
volt battery has recharged but will
start normally after the second
attempt. This is not a malfunction.
●The power switch mode is memo-
rized by the vehicle. When the 12-
volt battery is reconnected, the
system will return to the mode it
was in before the 12-volt battery
was discharged. Before discon-
necting the 12-volt battery, turn
the power switch off.
If you are unsure what mode the
power switch was in before the
12-volt battery discharged, be
especially careful when recon-
necting the 12-volt battery.
●When the 12-volt battery is recon-
nected, start the fuel cell system,
depress the brake pedal, and con-
firm that it is possible to shift into
each shift position.
●If the battery is removed or the ter-
minals disconnected without oper-
ating the water release function
during cold weather, the vehicle
may not start due to the fuel cell
system being frozen. To prevent
this, operate th e water release
function before removing the bat-
tery or disconnecting the termi-
nals. ( P.196)

4888-2. Steps to take in an emergency
Owners Manual_USA_M62064_en
■When replacing the 12-volt bat-
tery
●Use a Central Degassing type 12-
volt battery (European Regula-
tions).
●Use a 12-volt battery with the
same case size as the previous
12-volt battery and an equivalent
20 hour rate capacity (20HR) or
greater.
• If the sizes differ, the 12-volt bat- tery cannot be properly secured.
• If the 20 hour rate capacity is low,
even if the time period where the
vehicle is not used is a short time,
the 12-volt battery may discharge
and the fuel cell system may not
be able to start.
●Use a 12-volt battery with a han-
dle. If a 12-volt b attery without a
handle is used, removal is more
difficult.
●After replacing, firmly attach the
following items to the exhaust hole
of the 12-volt battery.
• Use the exhaust hose that was
attached to the 12-volt battery
before replacing an d confirm that
it is firmly connected to the hole
section of t he vehicle.
• Use the exhaust hole plug included with the 12-volt battery
replaced or the one installed on
the 12-volt battery prior to the
replacement. (Depending on the
12-volt battery to be replaced, the
exhaust hole may be plugged.)
Exhaust hole plug
Exhaust hole
Exhaust hose For details, consult your Toyota
dealer.
WARNING
■When removing the 12-volt
battery terminals
Always remove the negative (-)
terminal first. If the positive (+) ter-
minal contacts any metal in the
surrounding area when the posi-
tive (+) terminal is removed, a
spark may occur, leading to a fire
in addition to ele ctrical shocks
and death or serious injury.
■Avoiding 12-volt battery fires
or explosions
Observe the following precautions
to prevent accidentally igniting the
flammable gas that may be emit-
ted from the 12-volt battery:
●Make sure each jumper cable is
connected to the correct termi-
nal and that it is not unintention-
ally in contact with any other
than the intended terminal.
●Do not allow the other end of
the jumper cable connected to
the “+” terminal to come into
contact with any other parts or
metal surfaces in the area, such
as brackets or unpainted metal.
●Do not allow the + and - clamps
of the jumper cables to come
into contact with each other.
●Do not smoke, use matches,
cigarette lighter s or allow open
flame near the 1 2-volt battery.
■12-volt battery precautions
The 12-volt battery contains poi-
sonous and corrosive acidic elec-
trolyte, while related parts contain
lead and lead compounds.
Observe the following precautions
when handling the 12-volt battery:

4898-2. Steps to take in an emergency
Owners Manual_USA_M62064_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.
■When connecting jumper
cables
Make sure to connect jumper
cables to the specified terminals
and connecting point. Failure to
do so may adversely affect the
electronic devices or damage to
them.
■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.

4908-2. Steps to take in an emergency
Owners Manual_USA_M62064_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.455) 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.455) comes on
 Steam comes out from under the hood.
Parts name for cooling components