2021 TOYOTA AVALON HYBRID battery

3986-2. Maintenance
The OBD system determines that a problem exists somewhere in the
emission control system. Your vehicle may not pass the I/M test and
may need to be repaired. Contact your Toyota dealer to service the
vehicle.
●When the 12-volt battery is disconnected or discharged
Readiness codes that are set during ordinary driving are erased.
Also, depending on your driving habits, the readiness codes may
not be completely set.
●When the fuel tank cap is loose
The malfunction indicator lamp comes on indicating a temporary
malfunction and your vehicle may not pass the I/M test.
The error code in the OBD system will not be cleared unless the vehi-
cle is driven 40 or more times.
Contact your Toyota dealer to prepare the vehicle for re-testing.
Emission inspection and maintenance (I/M)
programs
Some states have vehicle emission inspection programs which
include OBD (On Board Diagnostics) checks. The OBD system
monitors the operation of the emission control system.
If the malfunction indicator lamp comes on
Your vehicle may not pass the I/M test in the following situations:
When the malfunction indicator lamp still remains on after sev-
eral driving trips
If your vehicle does not pass the I/M test

399
6
Maintenance and care
6-3. Do-it-yourself maintenance
Do-it-yourself ser vice precautions
If you perform maintenance by yourself, be sure to follow the
correct procedure as given in these sections.
ItemsParts and tools
12-volt battery
condition
(P. 411)•Grease
• Conventional wrench (for terminal clamp bolts)
Brake fluid level
(P. 409)
• SAE J1703 or FMVSS No.116 DOT 3
SAE J1704 or FMVSS No.116 DOT 4
• Rag or paper towel
• Funnel (used only for adding brake fluid)
Engine/power
control unit cool-
ant level
(P. 407)
• “Toyota Super Long Life Coolant” or a similar high
quality ethylene glycol-based non-silicate, non-
amine, non-nitrite and non-borate coolant with long-
life hybrid organic acid technology
“Toyota Super Long Life Coolant” is pre-mixed with
50% coolant and 50% deionized water.
• Funnel (used only for adding coolant)
Engine oil level
(P. 404)• “Toyota Genuine Motor Oil” or equivalent
• Rag or paper towel
• Funnel (used only for adding engine oil)
Fuses (P. 442)• Fuse with same amperage rating as original
Hybrid battery
(traction battery)
air intake vent
(P. 434)
• Vacuum cleaner, etc.
• Phillips screwdriver
Radiator/con-
denser (
P. 408)

4116-3. Do-it-yourself maintenance
6
Maintenance and care
The 12-volt battery is located on
the right-hand side of the trunk.
Remove the 12-volt battery cover.
12-volt batter y
Location
Removing the 12-volt battery cover

4126-3. Do-it-yourself maintenance
Make sure that the 12-volt battery terminals are not corroded and that
there are no loose connections, cracks, or loose clamps.
Terminals
Hold-down clamp
■Before recharging
When recharging, the 12-volt battery produces hydrogen gas which is flam-
mable and explosive. Therefore, observe the following precautions 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 connecting 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 possible 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 doors.
●Start the hybrid system with the power switch in ACCESSORY mode. The
hybrid system may not start with the power switch turned off. However, the
hybrid system will operate normally from the second attempt.
●The power switch mode is recorded by the vehicle. If the 12-volt battery is
reconnected, the vehicle will return the power switch mode to the status it
was in before the 12-volt battery was disconnected. Make sure to turn off
the power before disconnecting the 12-volt battery. Take extra care when
connecting the 12-volt battery if the power switch mode prior to discharge is
unknown.
If the system will not start even after multiple attempts, contact your Toyota
dealer.
Exterior
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4136-3. Do-it-yourself maintenance
6
Maintenance and care
WARNING
■Chemicals in the 12-volt battery
The 12-volt battery contains poisonous and corrosive sulfuric acid 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 with 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 battery.
●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 charge 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 may 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 get immedi-
ate medical attention. If possible, continue to apply water with 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 disconnecting the 12-volt battery
Do not disconnect the negative (-) terminal on the body side. The discon-
nected negative (-) terminal may touch the positive (+) terminal, which may
cause a short and result in death or serious injury.
■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 dealer.

4146-3. Do-it-yourself maintenance
NOTICE
■When recharging the 12-volt battery
Never recharge the 12-volt battery while the hybrid system is operating.
Also, be sure all accessories are turned off.

4346-3. Do-it-yourself maintenance
Remove the dust from the air
intake vent with a vacuum
cleaner, etc.
Make sure to only use a vacuum to
suck out dust and clogs. Attempt-
ing to blow out dust and clogs
using an airgun, etc. may push it
into the air intake vent. (P. 4 3 8 )
If dust and clogs cannot be completely removed with the air intake
vent cover installed, remove the cover and clean the filter.
Turn the power switch off.
Using a Phillips screwdriver,
remove the clip.
Cleaning the hybrid batter y (traction bat-
ter y) air intake vent and filter
To prevent the fuel economy from being affected, visually
inspect the hybrid battery (traction battery) air intake vent peri-
odically for dust and clogs. If it is dusty or clogged or if “Mainte-
nance Required for Traction Battery Cooling Parts See Owner’s
Manual” is displayed on the multi-information display, clean the
air intake vent using the following procedures:
Cleaning the air intake vent
If dust and clogs cannot be completely removed
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4376-3. Do-it-yourself maintenance
6
Maintenance and care
■Scheduled maintenance of the air intake vent is necessary when
In some situations such as when the vehicle is used frequently or in heavy
traffic or dusty areas, the air intake vent may need to be cleaned more regu-
larly. For details, refer to “Schedule maintenance guide” or “Owner’s Manual
Supplement”.
■Cleaning the air intake vent
●Dust in the air intake vent may interfere with the cooling of the hybrid battery
(traction battery). If charging/discharging of the hybrid battery (traction bat-
tery) becomes limited, the distance that the vehicle can be driven using the
electric motor (traction motor) may be reduced and the fuel economy may
be reduced.
●Improper handling of the air intake vent cover and filter may result in dam-
age to them. If you have any concerns about cleaning the filter, contact your
Toyota dealer.
■If “Maintenance Required for Traction Battery Cooling Parts See Owner’s
Manual” is displayed on the multi-information display
●If this warning message is displayed on the multi-information display,
remove the air intake vent cover and clean the filter. (P. 434)
●After cleaning the air intake vent, start the hybrid system and check that the
warning message is no longer displayed.
It may take approximately 20 minutes after the hybrid system is started until
the warning message disappears. If the warning message does not disap-
pear, have the vehicle inspected by your Toyota dealer.
WARNING
■When cleaning the air intake vent
●Do not use water or other liquids to clean the air intake vent. If water is
applied to the hybrid battery (traction battery) or other components, a mal-
function or fire may occur.
●Before cleaning the air intake vent, make sure to turn the power switch off
to stop the hybrid system.
■
When removing the air intake vent cover
Do not touch the service plug located near the air intake vent. (P. 82)