
5078-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
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 necessarily indicate a malfunction in the system. However, if this
continues to occur, have the vehicle inspected by any authorized Lexus
dealer or repairer, or another duly qualified and equipped professional.
Warning light and warning buzzer list
Warning lightWarning light/Details/Actions
Brake system warning light (warning buzzer)*1
Indicates that:
• The brake fluid level is low; or
• The brake system is malfunctioning
Immediately stop the vehicle in a safe place and contact any
authorized Lexus dealer or repairer, or another duly quali-
fied and equipped professional. Continuing to drive the
vehicle may be dangerous.
Brake system warning light
Indicates a malfunction in:
• The regenerative braking system; or
• The electronically controlled brake system
Have the vehicle inspected by any authorized Lexus dealer
or repairer, or another duly qualified and equipped profes-
sional immediately.
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 dealer or repairer, or another duly quali-
fied and equipped professional.
Malfunction indicator lamp
Indicates a malfunction in:
• The hybrid system;
• The emission control system (if equipped);
• The electronic engine control system; or
• The electronic throttle control system
Have the vehicle inspected by any authorized Lexus dealer
or repairer, or another duly qualified and equipped profes-
sional immediately.

5538-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
Once the hybrid system has started, remove the jumper cables in the
exact reverse order from which they were connected.
Once the hybrid system starts, have the vehicle inspected at any autho-
rized Lexus dealer or repairer, or another duly qualified and equipped
professional as soon as possible.
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 components 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 cer-
tain electrical appliances. 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 bat-
tery recharges automatically while the hybrid system is operating.)
When recharging or replacing the 12-volt battery
For vehicles with an alarm: Make sure that the key is not inside the vehicle
when recharging or replacing the 12-volt battery. The key may be locked in the
vehicle if the alarm is activated. (P. 98)
In some cases, it may not be possible to unlock the doors using the smart entry
& start system when the 12-volt battery is discharged. Use the wireless remote
control or the mechanical key to lock or unlock the doors.
The hybrid system may not start on the first attempt after the 12-volt battery has
recharged but will start normally after the second attempt. This is not a mal-
function.
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-volt battery, turn the
power switch off.
If you are unsure what mode the power switch was in before the 12-volt battery
discharged, be especially careful when reconnecting the 12-volt battery.
8

5548-2. Steps to take in an emergency
IS300h_EE(OM53B95E)
CAUTION
Avoiding 12-volt battery fires or explosions
Observe the following precautions to prevent accidentally igniting the flamma-
ble 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.
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 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,
immediately 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 the 12-volt battery support, terminals,
and other 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 dealer or repairer,
or another duly qualified and equipped professional as soon as possible.
If the 12-volt battery is deteriorating, continued use may cause the 12-volt bat-
tery to emit a malodorous gas, which may be detrimental to the health of pas-
sengers.
When replacing the 12-volt battery
P. 4 4 9

5689-1. Specifications
IS300h_EE(OM53B95E)
*: The fluid capacity is a reference quantity.
If replacement is necessary, contact any authorized Lexus dealer or repairer, or
another duly qualified and equipped professional.
Electrical system
12-volt battery
Open voltage at 20C
(68F):
12.5 V or higher: Fully charged
11.0 - 12.4 V: Half charged
10.9 V or lower: Discharged
(Check the voltage 20 minutes after the hybrid sys-
tem and all lights are turned off.)
Charging rates4 A — 5 A
Hybrid transmission
Fluid capacity*3.8 L (4.0 qt., 3.3 Imp. qt.)
Fluid typeToyota Genuine ATF WS
NOTICE
Hybrid transmission fluid type
Using transmission fluid other than “Toyota Genuine ATF WS” may cause
deterioration in shift quality, locking up of your transmission accompanied by
vibration, and ultimately damage the hybrid transmission of your vehicle.

611Alphabetical index
IS300h_EE(OM53B95E)
Warning buzzers
Approach warning ................254
Brake system ........................507
Downshifting ........................220
Driver’s and front
passenger’s seat belt
reminder ............................ 509
Lexus parking assist-sensor ..271
Open door .............................509
Pre-crash braking ..................299
Rear passengers’ seat belt
reminder .............................509
Warning lights ...........................105
ABS ......................................508
Automatic headlight leveling
system.................................509
Brake system ........................507
Charging system ...................507
Driver’s and front
passenger’s seat belt
reminder light .....................509
Electric power steering
system.................................508
Low fuel level .......................509
Malfunction indicator lamp ..507
Master warning light ............509
Open door .............................509
Pre-crash safety system ........508
Rear passengers’ seat belt
reminder lights ...................509
Slip indicator ........................508
SRS .......................................508
Tire pressure .........................510Warning messages .................... 514
Warning reflector storage belt .. 419
Washer ...................................... 235
Checking .............................. 446
Preparing and checking
before winter ..................... 311
Switch .................................. 235
Washing and waxing ................ 426
Weight ...................................... 562
Wheels ...................................... 468
Replacing ............................. 468
Size ...................................... 570
Window glasses ........................ 184
Window lock switch ................. 184
Windows................................... 184
Power windows.................... 184
Rear window defogger......... 404
Windshield wiper de-icer ......... 405
Windshield wipers .................... 235
Intermittent windshield wipers
with interval adjuster ......... 235
Rain-sensing windshield
wipers ................................ 237
Winter driving tips.................... 311
Wireless remote control............ 130
Battery-Saving Function ...... 150
Locking/Unlocking ...... 136, 143
Replacing the battery ........... 472
WMA disc ................................ 341
W