2021 TOYOTA SIENNA HYBRID battery replacement

861-4. Hybrid system
When a certain level of impact is
detected by the impact sensor,
the emergency shut off system
blocks the high voltage current
and stops the fuel pump to mini-
mize the risk of electrocution
and fuel leakage. If the emer-
gency shut off system activates,
your vehicle will not restart. To
restart the hybrid system, con-
tact your Toyota dealer.
A message is automatically dis-
played when a malfunction
occurs in the hybrid system or
an improper operation is
attempted.
If a warning message is shown
on the multi-information display,
read the message and follow the
NOTICE
■Hybrid battery (traction bat-
tery) air intake vents
●Make sure not to block the air
intake vents with anything, such
as a seat cover, plastic cover, or
luggage. If the vents become
blocked, the hybrid battery
(traction battery) input and out-
put may be restricted, leading to
a reduction in hybrid battery
(traction battery) output and a
malfunction.
●When dust etc. has accumu-
lated in the air intake vents,
clean them with a vacuum
cleaner to prevent the vents
from clogging.
●Do not get water or foreign
materials in the air intake vents
as this may cause a short circuit
and damage the hybrid battery
(traction battery).
●Do not carry large amounts of
water such as water cooler bot-
tles in the vehicle. If water spills
onto the hybrid battery (traction
battery), the battery may be
damaged. Have the vehicle
inspected by your Toyota
dealer.
●There are filters installed to the
air intake vents. When the filters
remain noticeably dirty even
after cleaning the air intake
vents, filters cleaning or
replacement is recommended.
For information regarding filters
cleaning or replacement, refer
to P.444.
●If “Maintenance Required for
Traction Battery Cooling Parts
See Owner’s Manual” is shown
on the multi-information dis-
play, the air intake vents and fil-
ters may be clogged. Refer to
P.443for information on how to
clean the air intake vents.
Emergency shut off sys-
tem
Hybrid warning message

1283-1. Key information
3-1.Key information
The following keys are provided
with the vehicle.Electronic keys
• Operating the smart key system ( P.164)
• Operating the wireless remote control function ( P.130)
Mechanical keys
Key number plate
■When riding in an aircraft
When bringing a key with wireless
remote control function onto an air-
craft, make sure y ou do not press
any buttons on the key while inside
the aircraft cabin. If you are carrying
the key in your bag etc., ensure that
the buttons are not likely to be
pressed accidentally. Pressing a
button may cause the key to emit
radio waves that could interfere with
the operation of the aircraft.
■Key battery depletion
●The standard battery life is 1 to 2
years.
●If the battery becomes low, an
alarm will sound in the cabin and a
message will be dis played on the
multi-information display when the
hybrid system stops.
●To reduce key battery depletion
when the electronic key is to not
be used for long periods of time,
set the electronic key to the bat-
tery-saving mode. ( P.166)
●As the electronic key always
receives radio waves, the battery
will become depleted even if the
electronic key is not used. The fol-
lowing symptoms indicate that the
electronic key battery may be
depleted. Replace the battery
when necessary.
• The smart key system or the wire-
less remote contro l does not oper-
ate.
• The detection area becomes
smaller.
• The LED indicator on the key sur- face does not turn on.
You can replace the battery by your-
self ( P.447). However, as there is
a danger that the electronic key may
be damaged, it is recommended
that replacement is carried out by
your Toyota dealer.
●To avoid serious deterioration, do
not leave the electronic key within
3 ft. (1 m) of the following electri-
cal appliances that produce a
magnetic field:
•TVs
• Personal computers
• Cellular phones, cordless phones and battery chargers
• Table lamps
• Induction cookers
●If the electronic key is near the
vehicle for longer than necessary,
even if the smart key system is not
used, the key battery may become
depleted faster than normal.
When not using the smart key sys-
tem, it is recommended not to stay
with the electronic key near the
vehicle longer than necessary.
■If a message regarding the state
of the electronic key or power
switch mode, e tc. is shown
To prevent trapping the electronic
Keys
Key types
A
B
C

3525-1. Using the air conditioning system and defogger
(Customizable features: P.551)
■Main control screen
Adjust the left side seat tem-
perature setting
Adjust the fan speed setting
Select the air flow mode
: Air flows to the upper body
: Air flows to the upper body and
feet
: Air flows to the feet
: Air flows to the feet and the
windshield defogger operates
Adjust the right side seat
temperature setting
Display the option control
screen. ( P.353)
“AUTO” switch (automatic
mode)
Set automatic mode on/off
(  P.353)
“OFF” switch
Turn the fan off
Set cooling and dehumidifi-
cation function
If “A/C” switch is not pressed, the
WARNING
■To prevent the windshield
from fogging up
Do not use the windshield defog-
ger switch during cool air opera-
tion in extremely humid weather.
The difference between the tem-
perature of the outside air and
that of the windshield can cause
the outer surface of the wind-
shield to fog up, blocking your
vision.
■To prevent burns
●Vehicles with outside rear view
mirror defoggers: Do not touch
the outside rear view mirror sur-
faces, as they can become very
hot and burn you.
●Vehicles with windshield wiper
deicer: Do not touch the glass at
lower part of the windshield or
to the side of the front pillars
when the windshield wiper de-
icer is on.
NOTICE
■To prevent 12-volt battery dis-
charge
Do not leave the air conditioning
system on longer than necessary
when the hybrid system is off.
■When repairing/replacing
parts of the air conditioning
system
Have repair/replacement per-
formed by your Toyota dealer.
When a part of th e air condition-
ing system, such as the evapora-
tor, is to be replaced, it must be
replaced with a new one.
Front air conditioning
control screen
A
B
C
D
E
F
G
H

4066-2. Maintenance
6-2.Maintenance
■Repair and replacement
It is recommended that genuine
Toyota parts be used for repairs to
ensure performanc e of each sys-
tem. If non-Toyota p arts are used in
replacement or if a repair shop other
than a Toyota dealer performs
repairs, confirm the warranty cover-
age.
■Allow inspection and repairs to
be performed by a Toyota
dealer
●Toyota technicians are well-
trained specialists and are kept up
to date with the latest service
information. They are well
informed about the operations of
all systems on your vehicle.
●Keep a copy of the repair order. It
proves that the maintenance that
has been performed is under war-
ranty coverage. If any problem
should arise while your vehicle is
under warranty, your Toyota
dealer will promptly take care of it.
General maintenance should be
performed on a daily basis. This
can be done by yourself or by a
Toyota dealer.
Scheduled maintenance should
be performed at specified inter-
vals according to the mainte-
nance schedule.
For details about maintenance
items and schedules, refer to the
“Scheduled Maintenance Guide” or
“Owner’s Manual Supplement”.
Maintenance require-
ments
To ensure safe and econom-
ical driving, day-to-day care
and regular maintenance
are essential. It is the
owner’s responsibility to
perform regular checks.
Toyota recommends the fol-
lowing maintenance:
WARNING
■If your vehicle is not properly
maintained
Improper maintenance could
result in serious damage to the
vehicle and possible death or seri-
ous injury.
■Handling of the 12-volt bat-
tery
●Engine exhaust, some of its
constituents, and a wide variety
of automobile components con-
tain or emit chemicals known to
the State of California to cause
cancer and birth defects and
other reproductive harm. Work
in a well ventilated area.
●Oils, fuels and fluids contained
in vehicles as well as waste pro-
duced by component wear con-
tain or emit chemicals known to
the State of California to cause
cancer and birth defects or
other reproductive harm. Avoid
exposure and wash any
affected area immediately.
●12-volt battery posts, terminals
and related accessories con-
tain lead and lead compounds
which are known to cause brain
damage. Wash your hands after
handling. ( P.422)
General maintenance
Scheduled maintenance

4236-3. Do-it-yourself maintenance
6
Maintenance and care
Remove the cover.
Make sure that the 12-volt bat-
tery terminals are not corroded
and that there are no loose con-
WARNING
●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 insuf-
ficient ventilation.
■Emergency measures regard-
ing electrolyte
●If electrolyte gets in your eyes
Flush your eyes with clean water
for at least 15 minutes and get
immediate medical attention. If
possible, continue to apply water
with a sponge or cloth while trav-
eling to the nearest medical facil-
ity.
●If electrolyte gets on your skin
Wash the affected area thor-
oughly. 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
clothing and follow the procedure
above if necessary.
●If you accidentally swallow elec-
trolyte
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. Failu re 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.
■When there is insufficient 12-
volt battery fluid
Do not use if ther e is insufficient
fluid in the 12-volt battery. There
is a possible danger that the 12-
volt battery may explode.
NOTICE
■When recharging the 12-volt
battery
Never recharge t he 12-volt bat-
tery while the hybrid system is
operating. Also, be sure all acces-
sories are turned off.
Removing the 12-volt bat-
tery cover
Exterior

5107-2. Steps to take in an emergency
WARNING
●Always wash your hands after
handling the 12-volt battery sup-
port, terminals, and other bat-
tery-related parts.
●Do not allow children 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
●For information regarding 12-
volt battery replacement, con-
tact your To yota dealer.
●After exchanging, securely
attach the exhaust hose and
exhaust hole plug to the
exhaust hole of the exchanged
12-volt battery. If not properly
installed, gases (hydrogen) may
leak into the vehicle interior, and
there is the possible danger of
the gas igniting and exploding.
NOTICE
■When handling jumper cables
When connecting the jumper
cables, ensure that they do not
become entangled in the cooling
fan, etc.
■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.

5238-1. Specifications
8
Vehicle specifications
*: The fluid capacity is the quantity of reference.If replacement is necessary, contact y our Toyota dealer.
*: The fluid capacity is the quantity of reference.
If replacement is necessary, contact y our Toyota dealer.
NOTICE
■Iridium-tipped spark plugs
Use only iridium-tipped spark plugs. Do not adjust the spark pl ug gap.
Electrical system (12-volt Battery)
Open voltage at 68°F (20°C):
12.0 V or higher
(Turn the power switch to OFF and turn on
the high beam headlights for 30 seconds.)
If the voltage is lower than the standard
value, charge the battery.
Charging rates5 A max.
Hybrid transmission
Fluid capacity*4.6 qt. (4.4 L, 3.9 Imp.qt.)
Fluid typeToyota Genuine ATF WS
NOTICE
■Hybrid transmission fluid type
Using transmission fluid other than the above type may cause ab normal
noise or vibration, or ultimately damage the transmission of yo ur vehicle.
Rear differential (rear electric motor) (AWD models)
Fluid capacity*1.8 qt. (1.7 L, 1.5 Imp.qt.)
Fluid typeToyota Genuine ATF WS
NOTICE
■Transmission fluid type
Using transmission fluid other than the above type may cause ab normal
noise or vibration, or ultimately damage the transmission of yo ur vehicle.