Page 947 of 1014
9207-2. Steps to take in an emergency
GS450h_300h_OM_OM30D53E_(EE)
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 your Lexus
dealer.
The coolant level is satisfactory if it is between the “F”/
“FULL” and “L”/“LOW” lines on the reservoir.
Reservoir
“F”/“FULL”
“L”/“LOW”
1
2
3
1
2
GS300hGS450h
4
1
2
3
GS300hGS450h
Page 949 of 1014
9227-2. Steps to take in an emergency
GS450h_300h_OM_OM30D53E_(EE)
Add coolant if necessary.
Water can be used in an emergency if power control unit 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 your Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the nearest Lexus dealer.
5
GS300hGS450h
6
Page 950 of 1014
923
7 7-2. Steps to take in an emergency
When trouble arises
GS450h_300h_OM_OM30D53E_(EE)
When adding coolant
Add coolant in accordance with the following procedure.
Remove caps A and B.
Add coolant through the inlet of cap A up to the B-line, and then install cap
A.
Add coolant through the inlet of cap B until it is full, and then install cap B.
GS300h only: When installing cap B, apply coolant to the O-ring on the
end of cap B.
Cap A
Cap B
B-line (Target fill line)
1
2
3
GS300h GS450h
1
2
3
Page 951 of 1014

9247-2. Steps to take in an emergency
GS450h_300h_OM_OM30D53E_(EE)
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 indicator on
the power switch and the “READY” indicator are off.
When the hybrid system is operating, the gasoline engine may automati-
cally start, or the cooling fan may suddenly operate even if the gasoline
engine stops. Do not touch or approach rotating parts such as the fan,
which may lead to fingers or clothing (especially a tie, a scarf or a muf-
fler) getting caught, resulting in serious injury.
Do not loosen the coolant inlet cap or
the coolant reservoir caps while the
hybrid system and radiator are hot.
High temperature steam or coolant
could spray out.
Page 952 of 1014
9257-2. Steps to take in an emergency
7
When trouble arises
GS450h_300h_OM_OM30D53E_(EE)
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 additives.
Page 964 of 1014
933
8 8-1. Specifications
Vehicle specifications
GS450h_300h_OM_OM30D53E_(EE)
Cooling system
Gasoline
engine
Power control unit
Left-hand
drive
vehiclesRight-hand
drive
vehicles
Capacity
GS300h8.4 L (8.9 qt.,
7.4 Imp.qt.)2.1 L (2.2 qt.,
1.8 Imp.qt.)2.3 L (2.4 qt.,
2.0 Imp.qt.)
GS450h9.4 L (9.9 qt.,
8.3 Imp.qt.)3.1 L (3.3 qt.,
2.7 Imp.qt.)2.9 L (3.1 qt.,
2.6 Imp.qt.)
Coolant typeUse either of the following:
• “Toyota Super Long Life Coolant”
• Similar high-quality ethylene glycol-based
non-silicate, non-amine, non-nitrite, and
non-borate coolant with long-life hybrid
organic acid technology
Do not use plain water alone.
Ignition system
Spark plug
Make
GapDENSO FK20HBR8
0.8 mm (0.031 in.)
NOTICE
Iridium-tipped spark plugs
Use only iridium-tipped spark plugs. Do not adjust the spark plug gap.
Page 997 of 1014

965Alphabetical index
GS450h_300h_OM_OM30D53E_(EE)
Child safety .................................58
12-volt battery
precautions .................752, 916
Airbag precautions..................47
Child restraint system .............59
How your child should
wear the seat belt ............39, 41
Installing child restraints ........71
Moon roof precautions .........221
Power window lock switch...215
Power window precautions...217
Rear door child-protectors ....184
Removed electronic key
battery precautions .............781
Seat belt comfort guide...........39
Seat belt precautions ...............43
Seat heater precautions .........703
Trunk precautions ................190
Child-protectors ........................184
Cleaning ............................720, 724
Aluminum wheels.................721
Exterior .................................720
Interior ..................................724
Seat belts...............................725Clock ........................................ 698
Coat hooks ................................ 715
Condenser ................................ 747
Console box .............................. 690
Console box light...................... 690
Coolant ..................................... 744
Capacity ............................... 933
Checking .............................. 744
Preparing and checking
before winter ..................... 434
Cooling system ......................... 744
Engine overheating .............. 917
Hybrid system overheating .. 917
Cruise control
Cruise control ...................... 298
Dynamic radar cruise control ....
302
Dynamic radar cruise control
with full-speed range ......... 319
Cup holders............................... 691
Curtain shield airbags ................ 45
Customizable features .............. 943
Page 1000 of 1014

968Alphabetical index
GS450h_300h_OM_OM30D53E_(EE)
Emergency brake signal ............399
Emergency flashers ...................820
Emergency tire puncture
repair kit ..................................885
Energy monitor..........................131
Engine .......................................928
Accessory mode....................247
Compartment ........................738
Engine switch .......................246
Hood .....................................734
How to start the hybrid
system.................................246
Identification number ...........928
Ignition switch
(power switch)....................246
Overheating ..........................917
Power switch ........................246
Engine compartment cover........740
Engine coolant ...........................744
Capacity ................................933
Checking ...............................744
Preparing and checking
before winter ......................434
Engine coolant temperature
gauge .......................................109
Engine oil ..................................741
Capacity ................................930
Checking ...............................741
Oil level warning message....853
Oil pressure warning
message ..............................841
Preparing and checking
before winter ......................434Engine switch ........................... 246
EPS (Electric Power Steering) . 398
Function ............................... 398
Warning light ....................... 833
Warning message................. 845
EV drive mode.......................... 254
First-aid kit storage net ............. 694
Flat tire
Vehicles with a spare tire..... 871
Vehicles without a spare tire 885
Floor mats ................................... 34
Fluid
Brake.................................... 935
Hybrid transmission............. 934
Washer ................................. 748
Fog lights .................................. 283
Replacing light bulbs ... 805, 818
Switch .................................. 283
Wattage ................................ 940
Follow me home system ........... 273
Footwell light ........................... 684
Front air conditioning system ... 478
Front fog lights ......................... 283
Replacing light bulbs ... 805, 818
Switch .................................. 283
Wattage ................................ 940
Front personal lights ................. 685
Front position lights.................. 272
Light switch ......................... 272
Replacing light bulbs ........... 818
Welcome light illumination
control ............................... 143
F