Page 633 of 692

6338-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53D89E)
Maintain the engine speed of the second vehicle and start the hybrid system
of your vehicle by turning the power switch to ON mode.
Make sure the “READY” indicator comes on. If the indicator does not come
on, contact any authorized Lexus retailer or Lexus authorized repairer, or any
reliable repairer.
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 authorized
Lexus retailer or Lexus authorized repair er, or any reliable repairer 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 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 w ill 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 repl acing the 12-volt battery
●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 malfunction.
●The power switch mode is memorized by the vehicle. When the 12-volt battery is reconnected, the system will retu rn to the mode it was in before the 12-volt battery was
discharged. Before disconnecting the 12-vol t 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.
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Page 634 of 692

6348-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
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 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 jump er cables to come into contact with each
other.
●Do not smoke, use matches, cigarette light ers or allow open flame near the 12-volt
battery.
■12-volt battery precautions
The 12-volt battery contains poisonous and co rrosive acidic electrolyte, while related
parts contain lead and lead compounds. Ob serve 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 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 retailer or Lexus autho-
rized repairer, or any reliable repairer as soon as possible.
If the 12-volt battery is deteriorating, co ntinued use may cause the 12-volt battery to emit a malodorous gas, which may be de trimental to the health of passengers.
■When replacing the 12-volt battery
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Page 635 of 692
6358-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53D89E)
NOTICE
■When handling jumper cables
When connecting the jumper cables, ensure th at they do not become entangled in the
cooling fans or belt.
■Exclusive jump starting terminal
The exclusive jump starting terminal is inte nded to charge the 12-volt battery on your
vehicle from another vehicle in an emergency. Do not use the exclusive jump starting
terminal to jump start another vehicle.
Page 636 of 692

6368-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
●The needle of the engine coolant temperature gauge (P. 105) enters the
red zone or a loss of hybrid system po wer is experienced. (For example, the
vehicle speed does not increase.)
●“Engine Coolant Temp High Stop in a Safe Place See Owner’s Manual” or
“Hybrid System Overheated Reduced Ou tput Power” is shown on the multi-
information display.
●Steam comes out from under the hood.
■If the needle of the engine coolant temperature gauge enters the red zone
Stop the vehicle in a safe place and tu rn off the air conditioning system, and
then stop the hybrid system.
If you see steam:
Carefully lift the hood after the steam subsides.
If you do not see steam:
Carefully lift the hood.
After the hybrid system has
cooled down sufficiently, inspect
the hoses and radiator core (radi-
ator) for any leaks.
Radiator
Cooling fans
If a large amount of coolant leaks,
immediately contact any autho-
rized Lexus retailer or Lexus authorized repairer, or any reli-
able repairer.
If your vehicle overheats
The following may indicate that your vehicle is overheating.
Correction procedures
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Page 637 of 692

6378-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53D89E)
The coolant level is satisfactory if
it is between the “FULL” and
“LOW” lines on the reservoir.
Reservoir
“FULL”
“LOW”
Add coolant if necessary.
Water can be used in an emergency if coolant is unavailable.
Start the hybrid system and turn the air conditioning system on to check
that the radiator cooling fans operate and to check for coolant leaks from
the radiator or hoses.
The fans operate when the air conditioning system is turned on immediately after a
cold start. Confirm that the fans are operating by checking the fan sound and air flow. If it is difficult to check these, tu rn the air conditioning system on and off
repeatedly.
(The fans may not operate in freezing temperatures.)
If the fans are not operating:
Stop the hybrid system immediatel y and contact any authorized Lexus
retailer or Lexus auth orized repairer, or any reliable repairer.
If the fans are operating:
Have the vehicle inspected at the nearest authorized Lexus retailer or
Lexus authorized repairer, or any reliable repairer.
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Page 638 of 692
6388-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
■If “Hybrid System Overheated Reduced Output Power” is shown on the
multi-information display
Stop the vehicle in a safe place.
Stop the hybrid system an d carefully lift the hood.
After the hybrid system has
cooled down, inspect the hoses
and radiator core (radiator) for
any leaks.
Radiator
Cooling fans
If a large amount of coolant leaks, immediately contact any autho-
rized Lexus retailer or Lexus
authorized repairer, or any reli- able repairer.
The coolant level is satisfactory if
it is between the “F” and “L” lines
on the reservoir.
Reservoir
“F”
“L”
Add coolant if necessary.
Water can be used in an emergency
if coolant is unavailable.
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2
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Page 639 of 692

6398-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53D89E)
Start the hybrid system and check if “Hybrid System Overheated Reduced
Output Power” is shown on the multi-information display.
If the message does not disappear:
Stop the hybrid system and contact an y authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer.
If the message is not displayed:
Have the vehicle inspected at the nearest authorized Lexus retailer or
Lexus authorized repairer, or any reliable repairer.
WARNING
■When inspecting under the hood of your vehicle
Observe the following precautions. Failure to do so may result in serious injury such as burns.
●If steam is seen coming from under the hood, do not open the hood until the steam
has subsided. The engine compartment may be very hot.
●After the hybrid system has been turned off, check that the “READY” indicator is off.
When the hybrid system operating, the gasoline engine may automatically start, or
the cooling fan may suddenly operate even if the gasoline engine stops. Do not touch or approach rotating parts such as the be lt and fan, which may lead to fingers or
clothing (especially a tie, a scarf or a mu ffler) getting caught, resulting in serious
injury.
6
●Do not loosen the c oolant reservoir caps or
water filler cap while th e hybrid system and
radiator are hot. High temperature steam or coolant could
spray out.
Page 640 of 692
6408-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
NOTICE
■When adding engine/power control unit coolant
Add coolant slowly after the hybrid system has cooled down sufficiently. Adding cool
coolant to a hot hybrid syst em too quickly can cause damage to the hybrid system.
■To prevent damage to the cooling system
Observe the following precautions:
●Avoid contaminating the coolant with foreig n matter (such as sand or dust etc.).
●Do not use any coolant additive.