Page 685 of 908
ES350 300h_OM_OM33A01U_(U)
6856-3. Do-it-yourself maintenance
6
Maintenance and care
Check the 12-volt battery as follows.
■12-volt battery exterior
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
■Checking 12-volt battery fluid
Check that the level is between the “UPPER LEVEL” and “LOWER
LEVEL” lines.
“UPPER LEVEL” line
“LOWER LEVEL” line
If the fluid level is at or below the
“LOWER LEVEL” line, add distilled
water.
NOTICE
■If the fluid level is low or high
It is normal for the brake fluid level to go down slightly as the brake pads wear out
or when the fluid level in the accumulator is high.
If the reservoir needs frequent refil ling, there may be a serious problem.
12-volt battery (gasoline vehicles)
1
2
1
2
Page 687 of 908

ES350 300h_OM_OM33A01U_(U)
6876-3. Do-it-yourself maintenance
6
Maintenance and care
■After recharging/reconnecting the 12-volt battery
The engine may not start. Follow the procedure below to initialize the system.
Shift the shift lever to P.
Open and close any of the doors.
Restart the engine.
●Unlocking the doors using the smart access system with push-button start may not
be possible immediately after reconnecting the 12-volt battery. If this happens, use
the wireless remote control or the me chanical key to lock/unlock the doors.
●Start the engine with the “START STOP ENGINE” switch in ACCESSORY mode.
The engine may not start with the “START STOP ENGINE” switch turned off. How-
ever, the engine will operate normally from the second attempt.
●The “START STOP ENGINE” switch mode is recorded by the vehicle. If the 12-volt
battery is reconnected, the vehicle will return the “START STOP ENGINE” switch
mode to the status it was in before the 12-volt battery was disconnected. Make sure
to turn off the engine before disconnect the 12-volt battery. Take extra care when
connecting the 12-volt battery if the “START STOP ENGINE” switch mode prior to
discharge is unknown.
If the engine will not start even after mu ltiple attempts, contact your Lexus dealer.
CAUTION
■Chemicals in the 12-volt battery
Batteries contain poisonous and corrosive sulfuric acid and may produce hydro-
gen 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.
1
2
3
Page 691 of 908

ES350 300h_OM_OM33A01U_(U)
6916-3. Do-it-yourself maintenance
6
Maintenance and care
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 prod uces hydrogen gas which is flammable
and explosive. Therefore, observe the following precautions before recharging:
●If recharging with the 12-volt battery installed on the vehicle, be sure to disconnect
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
●The hybrid system may not start. Follow the procedure below to initialize the system.
Shift the shift lever to P.
Open and close any of the doors.
Restart the hybrid system.
●Unlocking the doors using the smart access system with push-button start may not
be possible immediately after reconnecting the 12-volt battery. If this happens, use
the wireless remote control or the me chanical 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 status it was in
before the 12-volt battery was disconnect ed. Make sure to turn off the “POWER”
switch before disconnect 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 mult iple attempts at all methods above, contact
your Lexus dealer.
Exterior
1
2
1
2
3
Page 693 of 908

ES350 300h_OM_OM33A01U_(U)
6936-3. Do-it-yourself maintenance
6
Maintenance and care
CAUTION
■Emergency measures regarding electrolyte
●If electrolyte gets in your eyes
Flush your eyes with clean water for at least 15 minutes and get immediate medi-
cal 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 atten-
tion 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 electrolyte
Drink a large quantity of water or milk . Get emergency medical attention imme-
diately.
■When replacing the 12-volt battery
Use a 12-volt battery designed for this ve hicle. 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 Lexus dealer.
NOTICE
■When recharging the 12-volt battery
Never recharge the 12-volt battery while th e hybrid system is operating. Also, be
sure all accessories are turned off.
Page 711 of 908

ES350 300h_OM_OM33A01U_(U)
7116-3. Do-it-yourself maintenance
6
Maintenance and care
■Use a CR2032 lithium battery
●Batteries can be purchased at your Lexus dealer, local electrical appliance shops
or camera stores.
●Replace only with the same or equivalent type recommended by the manufacturer.
●Dispose of used batteries according to local laws.
■If the electronic key battery is depleted
The following symptoms may occur:
●The smart access system with push-button start and wireless remote control will
not function properly.
●The operational range will be reduced.
CAUTION
■Removed battery and other parts
Keep away from children. These parts are small and if swallowed by a child, they
can cause choking. Failure to do so could result in death or serious injury.
NOTICE
■For normal operation after replacing the battery
Observe the following precautions to prevent accidents:
●Always work with dry hands.
Moisture may cause the battery to rust.
●Do not touch or move any other component inside the remote control.
●Do not bend either of the battery terminals.
Page 719 of 908
ES350 300h_OM_OM33A01U_(U)
7196-3. Do-it-yourself maintenance
6
Maintenance and care
■Engine compartment (type B fuse box) (hybrid vehicles only)
FuseAmpereCircuit
1BATT FAN7. 5Battery cooling fan
2INV W/PMP RLY7. 5INV W/PMP RLY
3DC/DC IGCT10Hybrid system
4INV7. 5Hybrid system
5BATT VL SSR10Hybrid system
6PM IGCT7. 5Power management system, hybrid system
7IGCT-MAIN25INV W/PMP RLY, INV, DC/DC IGCT,
BATT VL SSR, PM IGCT, BATT FAN
8INV W/PMP15Hybrid system
Page 807 of 908

8077-2. Steps to take in an emergency
ES350 300h_OM_OM33A01U_(U)
7
When trouble arises
■When recharging or replacing the 12-volt battery
●Make sure the key is not inside the vehicle when recharging or replacing the 12-volt
battery to prevent the doors from being locked with the key left inside the vehicle
when the alarm operates.
●In some cases, it may not be possible to unlock the doors using the smart access
system with push-button start when the 12-volt battery is discharged. Use the wire-
less remote control or the mechanical key to lock or unlock the doors.
●The engine may not start on the first atte mpt after the 12-volt battery has recharged
but will start normally after the second attempt. This is not a malfunction.
●The “START STOP ENGINE” switch mode is memorized 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 disconnecting the 12-volt battery, turn
the “START STOP ENGINE” switch off.
If you are unsure what mode the “START STOP ENGINE” switch was in before the
12-volt battery discharged, be especially careful when reconnecting the 12-volt
battery.
CAUTION
■Avoiding 12-volt battery fires or explosions
Observe the following precautions to prev ent accidentally igniting the flammable
gas that may be emitted from the 12-volt battery:
●Make sure each jumper cable is connected to the correct terminal and that it is
not unintentionally 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 lighters or allow open flame near the 12-
volt battery.
Page 808 of 908

8087-2. Steps to take in an emergency
ES350 300h_OM_OM33A01U_(U)
CAUTION
■12-volt battery precautions
The 12-volt battery contains poisonous and corrosive acidic electrolyte, while
related parts contain lead and lead compounds. Observe the following precau-
tions when handling the 12-volt battery:
●When working with the 12-volt battery, always wear safety glasses and take care
not to allow any battery fluids (acid) to co me into contact with skin, clothing or the
vehicle body.
●Do not lean over the 12-volt battery.
●In the event that battery fluid comes into contact with the skin or eyes, immedi-
ately 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 th e battery support, terminals, and other
battery-related parts.
●Do not allow children near the 12-volt battery.
NOTICE
■When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in
the cooling fans or engine drive belt.