2021 LEXUS RX450h Owners Manual

3776-3. Do-it-yourself maintenance
6
Maintenance and care
2Remove the cover after removing
the clips.
1 Press
2 Pull out
RX450hL
1 Remove the deck board and side
auxiliary box cover. ( P.332)
2 Remove the 12-volt battery cover.
3 Remove the deck side trim cover.
■Before recharging
When recharging, the 12-volt battery pro-
duces hydrogen gas which is flammable
and explosive. Therefore, observe the fol- lowing precautions before recharging:
●If recharging with the 12-volt battery
installed on the vehicle, be sure to discon-
nect the ground cable.
●Make sure the power switch on the char-
ger is off when connecting and discon-
necting the charger cables to the 12-volt
battery.
■After recharging/reconnecting the
12-volt battery
●The hybrid system may not start. Follow
the procedure below to initialize the sys-
tem.
1 Shift the shift lever to P.
2 Open and close any of the doors.
3 Restart the hybrid system.
●Unlocking the doors using the smart
access system with pu sh-button start may
not be possible immediately after recon-
necting the 12-volt battery. If this hap-
pens, use the wireless 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 recon-
nected, the vehicle will return the power
switch mode to the stat us it was in before
the 12-volt battery was disconnected.
Make sure to turn off the power before
disconnect the 12-volt battery. Take extra
care when connecting the 12-volt battery
if the power switch mode prior to dis-
charge is unknown.
If the system will not start even after multiple
attempts at all the methods above, contact
your Lexus dealer.

3786-3. Do-it-yourself maintenance
WARNING
■Chemicals in the 12-volt battery
The 12-volt battery contains poisonous
and corrosive sulfuric acid and may pro-
duce hydrogen gas which is flammable
and explosive. To reduce the risk of death
or serious injury, take the following pre-
cautions 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 bat-
tery in a garage or closed room where
there is insufficient ventilation.
■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 immediate
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 clothing
and follow the procedure above if nec-
essary.
●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 com-
partment, causing a fire or explosion.
For replacement of the 12-volt battery,
contact your Lexus dealer.
■When handling the 12-volt battery
 P.453
■When disconnecting the 12-volt bat-
tery (RX450h)
Do not disconnect the negative (-) termi-
nal on the body side as shown. The dis-
connected negative (-) terminal may
touch the positive (+) terminal, which
may cause a short and result in death or
serious injury.
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.

3796-3. Do-it-yourself maintenance
6
Maintenance and care
RX450h
Make sure that the 12-volt battery ter-
minals are not corroded and that there
are no loose connections, cracks, or
loose clamps.
Terminals
Hold-down clamp
RX450hL
Make sure that the 12-volt battery ter-
minals are not corroded and that there
are no loose connections, cracks, or
loose clamps.
Terminals
Hold-down clamp
RX450h
Install the 12-volt battery cover with the
clips.
1 Push up center position
2 Insert
3 Press
RX450hL
1 Install the deck side trim cover.
2 Install the 12-volt battery cover.
Exterior
A
B
A
B
Installing the 12-volt battery
cover

3806-3. Do-it-yourself maintenance
Check if the treadwear indicators are
showing on the tires. Also check the
tires for uneven wear, such as excessive
wear on one side of 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 sidewall of each tire.
Replace the tires if the treadwear indica-
tors are showing on a tire.
■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 to expose the fabric,
and bulges indicating internal damage.
●A tire goes flat repe atedly or cannot be
properly repaired due to the size or loca-
tion of a cut or other damage.
If you are not sure, consult with your Lexus
dealer.
■Tire life
Any tire over 6 years old must be checked
by a qualified technician even if it has sel-
dom or never been used or damage is not
obvious.
■Proper storage of the spare tire
(RX450hL)
As an improperly stored spare tire may
cause damage to the wire cable that holds
it, check that the spare tire is stored prop-
erly on a daily basis.
●If the stored spare tire appears to be
slanted or rattles while driving, the spare
tire may not be properly stored. Store the
spare tire again by performing the follow-
ing tire change procedure correctly:
1 If the spare tire is slanted, the hoist
assembly may be stuck in the wheel
opening. If the spare tire rattles while
driving, it may not be fully raised. Lower
the spare tire to the ground and make
sure that the hoist assembly is perpen-
dicular to the wheel opening.
2 Raise the tire slowly and steadily until a
click is heard and the jack handle skips.
If the spare tire cannot be lowered, the wire
cable may be severed. Have the vehicle
Tires
Replace or rotate tires in accor-
dance with maintenance schedules
and treadwear.
Checking tires
A
B
C

3816-3. Do-it-yourself maintenance
6
Maintenance and care
inspected at your Lexus dealer.
■Maximum load of tire
Check that the maximum load of the
replacement tire is greater than 1/2 of the
Gross Axle Weight Ratings (GAWR) of
either the front axle or the rear axle, which-
ever 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.471)
■Tire types
●Summer tires
Summer tires are high-speed performance
tires best suited to highway driving under
dry conditions. Since summer tires do not
have the same traction performance as
snow tires, summer tires are inadequate for
driving on snow-covered or icy roads. For
driving on snow-covered roads or icy
roads, the use of snow tires is recom-
mended. When installing snow tires, be
sure to replace all four tires.
●All season tires
All season tires are designed to provide
better traction in snow and to be adequate
for driving in most winter conditions as well
as for use year-round. All season tires,
however, do not have adequate traction
performance compared with snow tires in
heavy or loose snow. Also, all season tires
fall short in acceleration and handling per-
formance compared with summer tires in
highway driving.
●Snow tires
For driving on snow-covered roads or icy roads, we recommend using snow tires. If
you need snow tires, select tires of the
same size, construction and load capacity
as the originally instal
led tires. Since your
vehicle has radial tires as original equip-
ment, make sure your snow tires also have
radial construction. Do not install studded
tires without first checking local regula-
tions for possible restrictions. Snow tires
should be installe d on all wheels. (P.291)
■If the tread on snow tires wears down
below 0.16 in. (4 mm)
The effectiveness of the tires as snow tires is
lost.
WARNING
■When inspecting or replacing tires
Observe the following precautions to
prevent accidents.
Failure to do so may cause damage to
parts of the drive train as well as danger-
ous handling characteristics, which may
lead to an accident resulting in death or
serious injury.
●Do not mix tires of different makes,
models or tread patterns.
Also, do not mix tires of remarkably
different treadwear.
●Do not use tire sizes other than those
recommended by Lexus.
●Do not mix differently constructed
tires (radial, bias-belted or bias-ply
tires).
●Do not mix summer, all season and
snow tires.
●Do not use tires that have been used
on another vehicle.
Do not use tires if you do not know
how they were used previously.
●Do not tow if your vehicle has a com-
pact spare tire installed.

3826-3. Do-it-yourself maintenance
Rotate the tires in the order shown.
To equalize tire wear and extend tire life,
Lexus recommends that tire rotation is car-
ried out at the same interval as tire inspec-
tion.
Do not fail to initialize the tire pressure
warning system after tire rotation.
Your vehicle is equipped with a tire
pressure warning system that uses tire
pressure warning valves and transmit-
ters to detect low tire inflation pressure
before serious problems arise.
The tire pressure detected by the tire pressure warning system can be
displayed on the multi-information
display. (
P.88)
The illustration used is intended as an
example, and may differ from the image
that is actually displayed on the multi-infor-
mation display.
 If the tire pressure drops below a
predetermined level, the driver is
warned by a screen display and a
warning light. ( P.422)
The illustration used is intended as an
example, and may differ from the image
that is actually displayed on the multi-infor-
mation display.
■Routine tire inflation pressure checks
The tire pressure warning system does not
replace routine tire inflation pressure
checks. Make sure to check tire inflation
pressure as part of your routine of daily
vehicle checks.
NOTICE
■Driving on rough roads
Take particular care when driving on
roads with loose surfaces or potholes.
These conditions may cause losses in tire
inflation pressure, reducing the cushion-
ing ability of the tires. In addition, driving
on rough roads may cause damage to
the tires themselves, as well as the vehi-
cle’s wheels and body.
■If tire inflation pres sure of each tire
becomes low while driving
Do not continue driving, or your tires
and/or wheels may be ruined.
Tire rotation
Tire pressure warning system

3836-3. Do-it-yourself maintenance
6
Maintenance and care
■Situations in which the tire pressure
warning system may not operate prop-
erly
●In the following cases, the tire pressure
warning system may not operate prop-
erly.
• If non-genuine Lexus wheels are used.
• A tire has been replaced with a tire that is
not an OE (Original Equipment) tire.
• A tire has been replaced with a tire that is
not of the specified size.
• Tire chains, etc. are equipped.
• If a window tint that affects the radio wave signals is installed.
• If there is a lot of snow or ice on the vehi- cle, particularly around the wheels or
wheel housings.
• If the tire inflation pressure is extremely higher than the specified level.
• If wheel without the tire pressure warning
valve and transmitter is used.
• If the ID code on the tire pressure warn- ing valves and transmitters is not regis-
tered in the tire pressure warning
computer.
●Performance may be affected in the fol-
lowing situations.
• Near a TV tower, electric power plant, gas station, radio stat
ion, large display,
airport or other fac ility that generates
strong radio waves or electrical noise
• When carrying a portable radio, cellular phone, cordless phone or other wireless
communication device
If tire position information is not correctly
displayed due to the radio wave conditions,
the display may be corrected by driving and
changing the radio wave conditions.
●When the vehicle is parked, the time
taken for the warning to start or go off
could be extended.
●When tire inflation pr essure declines rap-
idly for example when a tire has burst, the
warning may not function.
■Warning performance of the tire pres-
sure warning system
The warning of the tire pressure warning
system will change in accordance with the
conditions under which it was initialized. For
this reason, the system may give a warning
even if the tire pressure does not reach a
low enough level, or if the pressure is higher
than the pressure that was adjusted to when
the system was initialized.
■Tire pressure warning system certification
Except for vehicles sold in Canada

3846-3. Do-it-yourself maintenance
For vehicles sold in Canada
When replacing tires or wheels, tire
pressure warning valves and transmit-
ters 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 warn-
ing valve and transmitter ID codes reg-
istered by your Lexus dealer.
Installing tire pressure warning
valves and transmitters