Page 525 of 612
5258-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53C61E)
*: The hybrid system may not be restarted depending on the vehicle condition.
■Warning messages
→P. 5 2 0
■Warning buzzer
→P. 5 0 7
Once
Indicates that the power switch has
been pressed while driving
→Except when emergency stop-
ping of the vehicle is needed,
immediately release the power
switch.
Interior
buzzerExteriorbuzzerWarning messageDetails/Actions
(Flashes)
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Page 546 of 612

5468-2. Steps to take in an emergency
IS300h_EE(OM53C61E)
■Stopping the hybrid system
Shift the shift lever to P and press the power switch as you normally do when stopping the
hybrid system.
■Replacing the key battery
As the above procedure is a temporary measure, it is recommended that the electronic
key battery be replaced immediately when the battery is depleted. (→P. 4 7 1 )
■Alarm (if equipped)
Using the mechanical key to lock the doors will not set the alarm system.
If a door is unlocked using the mechanical key when the alarm system is set, the alarm
may be triggered.
■Changing power switch modes
Release the brake pedal and press the power switch in step above.
The hybrid system does not start and modes will be changed each time the switch is
pressed. (→P. 2 1 0 )
■When the electronic key does not work properly
●Make sure that the smart entry & start system has not been deactivated in the customi-
zation setting. If it is off, turn the function on.
(Customizable features →P. 5 7 3 )
●Check if battery-saving mode is set. If it is set, cancel the function. (→P. 1 5 0 )
CAUTION
■When using the mechanical key and operating the power windows and moon roof
Operate the power window or moon roof after checking to make sure that there is no
possibility of any passenger having any of their body parts caught in the window or
moon roof. Also, do not allow children to operate the mechanical key. It is possible for
children and other passengers to get caught in power window and moon roof.
3
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Page 553 of 612

5538-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53C61E)
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, turn 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 immediately and contact any authorized Lexus
dealer or repairer, or another duly qualified and equipped professional.
If the fans are operating:
Have the vehicle inspected at the nearest authorized Lexus dealer or
repairer, or another duly qualified and equipped professional.
■If “Hybrid System Overheat” is shown on the multi-information display
Stop the vehicle in a safe place.
Stop the hybrid system and 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 dealer or repairer, or
another duly qualified and
equipped professional.
5
6
7
1
2
3
1
2
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Page 554 of 612
5548-2. Steps to take in an emergency
IS300h_EE(OM53C61E)
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.
Start the hybrid system and check for the multi-information display.
If the message does not disappear:
Stop the hybrid system and contact any authorized Lexus dealer or
repairer, or another duly qualified and equipped professional.
If the message is not displayed:
Have the vehicle inspected at the nearest authorized Lexus dealer or
repairer, or another duly qualified and equipped professional.
4
1
2
3
5
6
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Page 555 of 612

5558-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53C61E)
CAUTION
■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 belt and fan, which may lead to fingers or
clothing (especially a tie, a scarf or a muffler) getting caught, resulting in serious
injury.
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 system 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 foreign matter (such as sand or dust etc.).
●Do not use any coolant additive.
●Do not loosen the coolant reservoir caps or
water filler cap while the hybrid system and
radiator are hot.
High temperature steam or coolant could
spray out.
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Page 556 of 612
5568-2. Steps to take in an emergency
IS300h_EE(OM53C61E)
Stop the hybrid system. Set the parking brake and shift the shift lever to P.
Remove the mud, snow or sand from around the rear wheels.
Place wood, stones or some other material under the rear wheels to help pro-
vide traction.
Restart the hybrid system.
Shift the shift lever to D or R and release the parking brake. Then, while exer-
cising caution, depress the accelerator pedal.
■When it is difficult to free the vehicle
If the vehicle becomes stuck
Carry out the following procedures if the tires spin or the vehicle becomes
stuck in mud, dirt or snow:
Press to turn off TRC.
1
2
3
4
5
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Page 582 of 612

5829-2. Customization
IS300h_EE(OM53C61E)
■Vehicle customization
●When the speed-detecting automatic door lock and shift-linked automatic door lock
are both on, the door lock operates as follows.
• When shifting the shift lever to any position other than P, all the doors will be locked.
• If the vehicle is started with all doors locked, the speed-detecting automatic door
lock will not operate.
• If the vehicle is started with any door unlocked, the speed-detecting automatic door
lock will operate.
●When the smart entry & start system is off, the entry unlock function cannot be custom-
ized.
●When the doors remain closed after unlocking the doors and the timer activated auto-
matic door lock function activates, signals will be generated in accordance with the
operation buzzer volume and operational signal (Emergency flashers) function set-
tings.
■When customizing using the Remote Touch or Lexus Display Audio controller
Stop the vehicle in a safe place, apply the parking brake, and shift the shift lever to P. Also,
to prevent 12-volt battery discharge, leave the hybrid system operating while customiz-
ing the features.
CAUTION
■During customization
As the hybrid system needs to be operating during customization, ensure that the vehi-
cle is parked in a place with adequate ventilation. In a closed area such as a garage,
exhaust gases including harmful carbon monoxide (CO) may collect and enter the
vehicle. This may lead to death or a serious health hazard.
NOTICE
■During customization
To prevent 12-volt battery discharge, ensure that the hybrid system is operating while
customizing features.
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Page 587 of 612

587What to do if... (Troubleshooting)
IS300h_EE(OM53C61E)
●The function to prevent the electronic key from being left inside the trunk will
operate and you can open the trunk as usual. Take the key out from the trunk.
(→P. 1 4 6 )
●Did you press the power switch while firmly depressing the brake pedal?
(→P. 2 0 9 )
●Is the shift lever in P? (→P. 211)
●Is the electronic key anywhere detectable inside the vehicle? (→P. 1 4 9 )
●Is the steering wheel unlocked? (→P. 212)
●Is the electronic key battery weak or depleted?
In this case, the hybrid system can be started in a temporary way. (→P. 5 4 5 )
●Is the 12-volt battery discharged? (→P. 5 4 7 )
●Is the power switch in ON mode?
If you cannot release the shift lever by depressing the brake pedal with the
power switch in ON mode. (→P. 5 4 3 )
●It is locked automatically to prevent theft of the vehicle. (→P. 212) The trunk lid is closed with the electronic key left inside
If you think something is wrong
The hybrid system does not start
The shift lever cannot be shifted from P even if you depress the brake
pedal
The steering wheel cannot be turned after the hybrid system is stopped
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