
413 6-3. Do-it-yourself maintenance
6
Maintenance and care
GS450h_300h_OM_OM30F92E_(EE)
The meanings of each caution symbol on the top of the 12-volt battery are as fol-
lows:
■Before recharging
When recharging, the 12-volt battery produces 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 disconnecting
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 entry & start system may not be possible immedi- ately after reconnecting the 12-volt battery. If this happens, use the wireless remotecontrol or the mechanical key to lock/unlock the doors.
●Start the hybrid system with the power switch in ACCESSORY mode. The hybrid sys-tem may not start with the power switch turned off. However, the hybrid system willoperate 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 tu rn 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 multiple attempts at all methods above, contact any
authorized Lexus retailer or Lexus author ized repairer, or any reliable repairer.
Caution symbols
No smoking, no naked flames, no sparks12-volt battery acid
Shield eyesNote operating instructions
Keep away from childrenExplosive gas
1
2
3

4146-3. Do-it-yourself maintenance
GS450h_300h_OM_OM30F92E_(EE)
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 th ere is insufficient ventilation.
■How to recharge the 12-volt battery
Recharge at a current of 5 A or less and make sure that the recharging period does not
exceed a total of 12 hours.
■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 tothe nearest medical facility.
●If electrolyte gets on your skinWash the affected area thoroughly. If you f eel pain or burning, get medical attention immediately.
●If electrolyte gets on your clothesIt can soak through clothing on to your skin. Immediately take off the clothing and fol-low the procedure above if necessary.
●If you accidentally swallow electrolyteDrink a large quantity of water or milk. Get emergency medical attention immedi-ately.
■When replacing the 12-volt battery
Use a 12-volt battery designed for this vehicle. Failure to do so may cause gas (hydro- gen) to enter the passenger compartment, causing a fire or explosion.
For replacement of the 12-volt battery, contact any authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer.

415 6-3. Do-it-yourself maintenance
6
Maintenance and care
GS450h_300h_OM_OM30F92E_(EE)
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.

4607-2. Steps to take in an emergency
GS450h_300h_OM_OM30F92E_(EE)
If a warning light turns on or a warning buzzer
sounds
Calmly perform the following actions if any of the warning lights comes on or
flashes. If a light comes on or flashes, but then goes off, this does not necessar-
ily indicate a malfunction in the system. However, if this continues to occur,
have the vehicle inspected by any authorized Lexus retailer or Lexus autho-
rized repairer, or any reliable repairer.
Warning light and warning buzzer list
Warning lightWarning light/Details/Actions
Brake system warning light (warning buzzer)
•Low brake fluid • Malfunction in the electronically controlled brake system Immediately stop the vehicle in a safe place and contact any
authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer. Continuing to drive the vehicle may be dan-gerous.
(If equipped)
Charging system warning light
Indicates a malfunction in the vehicle’s charging system Immediately stop the vehicle in a safe place and contact any authorized Lexus retailer or Lexus authorized repairer, or any
reliable repairer.
Malfunction indicator lamp Indicates a malfunction in:• The hybrid system;
• The emission control system (if equipped); • The electronic engine control system; • The electronic throttle control system; or
• The electronic hybrid transmission control system (if equipped) Have the vehicle inspected by any authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer immediately.
SRS warning light
Indicates a malfunction in: • The SRS airbag system; or• The seat belt pretensioner system
Have the vehicle inspected by any authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer immediately.

4757-2. Steps to take in an emergency
7
When trouble arises
GS450h_300h_OM_OM30F92E_(EE)
Indicates a malfunction in:
• The SRS airbag system; or • The seat belt pretensioner systemA buzzer also sounds.
Have the vehicle inspected by any authorized Lexus retailer or Lexus authorized repairer, or any reliablerepairer.
Indicates a malfunction in:•The ABS; or• The brake assist system
A buzzer also sounds. Immediately stop the vehicle in a safe place and contact any authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer.
Indicates that the engine coolant temperature is too high
A buzzer also sounds. P. 535
Indicates a malfunction in the vehicle’s charging system. Immediately stop the vehicle in a safe place and contact any authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer.
Warning messageDetails/Actions

5337-2. Steps to take in an emergency
7
When trouble arises
GS450h_300h_OM_OM30F92E_(EE)
■Starting the hybrid system when the 12-volt battery is discharged
The hybrid system cannot be started by push-starting.
■To prevent 12-volt battery discharge
●Turn off the headlights and the audio system while the hybrid system is off.
●Turn off any unnecessary electrical componen ts when the vehicle is running at a low speed for an extended period, such as in heavy traffic.
■Charging the 12-volt battery
The electricity stored in the 12-volt battery will discharge gradually even when the vehicle is not in use, due to natural discharge and the draining effects of certain electrical appli-ances. If the vehicle is left for a long time, the 12-volt battery may discharge, and the
hybrid system may be unable to start. (The 12-volt battery recharges automatically while the hybrid system is operating.)
■When recharging or replacing the 12-volt battery
●In some cases, it may not be possible to unlock the doors using the smart entry & startsystem when the 12-volt battery is discharged. Use the wireless remote control or themechanical key to lock or unlock the doors.
●The hybrid system may not start on the first attempt after the 12-volt battery hasrecharged but will start normally after the second attempt. This is not a malfunction.
●The power 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-v olt battery, turn the power switch off. If you are unsure what mode the power switch was in before the 12-volt battery dis-
charged, be especially careful when reconnecting the 12-volt battery.
WARNING
■Avoiding 12-volt battery fires or explosions
Observe the following precautions to prevent 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 notunintentionally 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.

5347-2. Steps to take in an emergency
GS450h_300h_OM_OM30F92E_(EE)
WARNING
■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 precautions when han-
dling the 12-volt battery:
●When working with the 12-volt battery, always wear safety glasses and take care not to allow any 12-volt battery fluids (acid) to come into contact with skin, clothing or the
vehicle body.
●Do not lean over the 12-volt battery.
●In the event that 12-volt 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 bereceived.
●Always wash your hands after handling the 12-volt battery support, terminals, andother battery-related parts.
●Do not allow children near the 12-volt battery.
■After recharging the 12-volt battery
Have the 12-volt battery inspected at any authorized Lexus retailer or Lexus autho- rized repairer, or any reliable repairer as soon as possible.
If the 12-volt battery is deteriorating, continued use may cause the 12-volt battery to emit a malodorous gas, which may be detrimental to the health of passengers.
■When replacing the 12-volt battery
P. 414
NOTICE
■When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in the cooling fans or belt.
■To prevent damaging the vehicle
The exclusive jump starting terminal 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.

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8
8-1. Specifications
Vehicle specifications
GS450h_300h_OM_OM30F92E_(EE)
*: The fluid capacity is the quantity of reference.
If replacement is necessary, contact any authorized Lexus retailer or Lexus autho-
rized repairer, or any reliable repairer.
Electrical system
12-volt battery
Open voltage at 20 C (68F):12.0 V or higher
(Voltage is checked 20 minutes after the hybrid system and all lights are turned off.)
Charging rates5 A max.
Hybrid transmission
Fluid capacity*GS450h5.69 L (6.01 qt., 5.01 Imp.qt.)
GS300h3.80 L (4.02 qt., 3.34 Imp.qt.)
Fluid typeToyota Genuine ATF WS
NOTICE
■Hybrid transmission fluid type
Using transmission fluid other than “Toyot a Genuine ATF WS” may cause deterioration in shift quality and ultimately damage the transmission of your vehicle.