2020 TOYOTA MIRAI maintenance

3757-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
7
Maintenance and care
Install the 12-volt battery cover.
■Before recharging
When recharging, the 12-volt battery produces hydrogen gas which is flam-
mable and explosive. Therefore, observe the following precautio ns before
recharging:
● If recharging with the 12-volt battery installed on the vehicle , be sure to dis-
connect the ground cable.
● Make sure the power switch on the charger is off when connectin g and dis-
connecting the charger cables to the 12-volt battery.
■ After recharging/reconnecting the 12-volt battery
●Unlocking the doors using the smart key system may not be possi ble imme-
diately after reconnecting the 12-volt battery. If this happens, use the wire-
less remote control or the mechanical key to lock/unlock the do ors.
● Start the fuel cell system with the power switch in ACCESSORY m ode. The
fuel cell system may not start with the power switch turned off. However, the
fuel cell system will operate normally from the second attempt.
● The power switch mode is recorded by the vehicle. If the 12-vol t battery is
reconnected, the vehicle will return the power switch mode to t he status it
was in before the 12-volt battery was disconnected. Make sure t o turn off
the power before disconnect the 12-volt battery. Take extra car e when con-
necting the 12-volt battery if the power switch mode prior to d ischarge is
unknown.
● When the 12-volt battery is reconnected, start the fuel cell sy stem, depress
the brake pedal, and confirm that it is possible to shift into each shift posi-
tion.
If the system will not start even after multiple attempts at al l methods above,
contact your Toyota dealer.
Installing the 12-volt battery cover

3767-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
WARNING
■Chemicals in the 12-volt battery
The 12-volt battery contains poisonous and corrosive sulfuric a cid and may
produce hydrogen gas which is flammable and explosive. To reduce the risk
of death or serious injury, take the following precautions while working on or
near the 12-volt battery:
● Do not cause sparks by touching the 12-volt battery terminals w ith tools.
● Do not smoke or light a match near the 12-volt battery.
● Avoid contact with eyes, skin and clothes.
● Never inhale or swallow electrolyte.
● Wear protective safety glasses when working near the 12-volt ba ttery.
● Keep children away from the 12-volt battery.
■ Where to safely charge the 12-volt battery
Always charge the 12-volt battery in an open area. Do not charg e the
12-volt battery in a garage or closed room where there is insufficient ventila-
tion.
■ How to recharge the 12-volt battery
Only perform a slow charge (5 A or less). The 12-volt battery m ay explode if
charged at a quicker rate.
■ Emergency measures regarding electrolyte
● If electrolyte gets in your eyes
Flush your eyes with clean water for at least 15 minutes and ge t immedi-
ate medical attention. If possible, continue to apply water wit h a sponge or
cloth while traveling to the nearest medical facility.
● If electrolyte gets on your skin
Wash the affected area thoroughly. If you feel pain or burning, get medical
attention immediately.
● If electrolyte gets on your clothes
It can soak through clothing on to your skin. Immediately take off the cloth-
ing and follow the procedure above if necessary.
● If you accidentally swallow electrolyte
Drink a large quantity of water or milk. Get emergency medical attention
immediately.
■ When replacing the 12-volt battery
Use a 12-volt battery designed for this vehicle. Failure to do so may cause
gas (hydrogen) to enter the passenger compartment, causing a fire or
explosion.
For replacement of the 12-volt battery, contact your Toyota dea ler.

3777-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
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Maintenance and care
NOTICE
■When recharging th e 12-volt battery
Never recharge the 12-volt battery while the fuel cell system i s operating.
Also, be sure all accessories are turned off.

3787-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
Tires
Check if the treadwear indicators are showing on the tires. Also check
the tires for uneven wear, such as excessive wear on one side o f the
tread.
Check the spare tire condition and pressure if not rotated.
New tread
Worn tread
Treadwear indicator
The location of treadwear indicators is shown by a “TWI” or “ ” mark,
etc., molded into the s idewall of each tire.
Replace the tires if the treadwear indicators are showing on a tire.
Rotate the tires in the order
shown.
To equalize tire wear and extend
tire life, Toyota recommends that
tire rotation is carried out at the
same interval as tire inspection.
Replace or rotate tires in accordance with maintenance sched-
ules and treadwear.
Checking tires
Tire rotation
Front

3797-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
7
Maintenance and care
Your vehicle is equipped with a tire pressure warning system that uses
tire pressure warning valves and transmitters to detect low tire infla-
tion pressure before serious problems arise.
If the tire pressure drops below a predetermined level, the dri ver is
warned by a warning light. ( P. 421)
◆Installing tire pressure warn ing valves and transmitters
When replacing tires or wheels, tire pressure warning valves an d
transmitters must also be installed.
When new tire pressure warning valves and transmitters are
installed, new ID codes must be registered in the tire pressure
warning computer and the tire pressure warning system must be
initialized. Have tire pressure warning valves and transmitter ID
codes registered by your Toyota dealer. ( P. 379)
◆Registering ID codes
The tire pressure warning valve and transmitter is equipped wit h a
unique ID code. When replacing a tire pressure warning valve an d
transmitter, it is necessary to register the ID code. Have the ID code
registered by your Toyota dealer.
Tire pressure warning system

3807-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
■When to replace your vehicle’s tires
Tires should be replaced if:
●The treadwear indicators are showing on a tire.
●You have tire damage such as cuts, splits, cracks deep enough t o
expose the fabric, and bulges indicating internal damage
●A tire goes flat repeatedly or c annot be properly repaired due to the size
or location of a cut or other damage
If you are not sure, consult with your Toyota dealer.
■Replacing tires and wheels
If the ID code of the tire press ure warning valve and transmitt er is not reg-
istered, the tire pressure warni ng system will not work properly. A f t e r d r i v -
ing for about 20 minutes, the tire pressure warning light blink s for 1
minute and stays on to indi cate a system malfunction.
■Tire life
Any tire over 6 years old must be checked by a qualified techni cian even
if it has seldom or never been u sed or damage is not obvious.
■Routine tire inflation pressure checks
The tire pressure warning system does not replace routine tire inflation
pressure checks. Make sure to chec k tire inflation pressure as part of
your routine of daily vehicle checks.
■Maximum load of tire
Check that the maximum load of t he replacement tire is greater than 1/2
of the Gross Axle Weight Ratings (GAWR) of either the front axl e or the
rear axle, whichever is greater.
For the GAWR, see the Certification
Label. For the maximum load of the tire,
see the load limit at maximum cold tire
inflation pressure mentioned on the
sidewall of the tire. ( P. 4 7 2 )

3817-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
7
Maintenance and care
■Tire types
●Summer tires
Summer tires are high-speed performance tires best suited to highway
driving under dry conditions. Si nce summer tires do not have th e same
traction performance as snow tires, summer tires are inadequate for
driving on snow-covered or icy ro ads. For driving on snow-covered
roads or icy roads, the use of snow tires is recommended. When install-
ing snow tires, be sure to replace all four tires.
●All season tires
All season tires are designed to provide better traction in sno w and to
be adequate for driving in most winter conditions as well as fo r use
year-round. All season tires, however, do not have adequate tra ction
performance compared with snow tires in heavy or loose snow. Al so, all
season tires fall short in acceleration and handling performanc e com-
pared with summer tires in highway driving.
●Snow tires
For driving on snow-covered roads or icy roads, we recommend us ing
snow tires. If you need snow tires, select tires of the same si ze, con-
struction and load capacity as t he originally installed tires. Since your
vehicle has radial tires as original equipment, make sure your snow
tires also have radial construct ion. Do not install studded tires without
first checking local regulations for possible restrictions. Sno w tires
should be install ed on all wheels. ( P. 301)
■If the tread on snow tires wea rs down below 0.16 in. (4 mm)
The effectiveness of the tires as snow tires is lost.

3827-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U■
Situations in which the tire pressure warning system may not op
er-
ate properly
●In the following cases, the tire pressure warning system may no t operate
properly.
• If non-genuine Toyota wheels are used.
• A tire has been replaced with a tire that is not an OE (Original Equip-
ment) tire.
• A tire has been replac ed with a tire that is not of the specif ied size.
• Tire chains, etc., are equipped.
• An auxiliary-supported ru n-flat tire is equipped.
• If a window tint that affects the radio wave signals is instal led.
• If there is a lot of snow or ice on the vehicle, particularly around the
wheels or wheel housings.
• If the tire inflation pressure is extremely higher than the sp ecified
level.
• If wheels without the tire pressure warning valves and transmi tters
are used.
• If the ID code on the tire pressure warning valves and transmi tters is
not registered in the tire pressure warning computer.
●Performance may be affected in the following situations.
• Near a TV tower, electric power plant, gas station, radio stat ion, large
display, airport or other facilit y that generates strong radio waves or
electrical noise
• When carrying a portable radio, cellular phone, cordless phone or
other wireless communication device
●When the vehicle is parked, the time taken for the warning to s tart or go
off could be extended.
●When tire inflation pressure declines rapidly for example when a tire has
burst, the warning may not function.