2017 Lexus GS300h cooling

4046-3. Do-it-yourself maintenance
GS450h_300h_OM_OM30F92E_(EE)
GS300h
■12-volt battery P. 412
Power control unit coolant
reservoir ( P. 409)
Engine oil level dipstick ( P. 406)
Engine oil filler cap ( P. 407)
Engine coolant reservoir ( P. 409) Fuse box (
P. 437)
Washer fluid tank ( P. 411)
Electric cooling fans
Condenser ( P. 411)
Radiator ( P. 411)1
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4106-3. Do-it-yourself maintenance
GS450h_300h_OM_OM30F92E_(EE)
■Coolant selection
Only use “Toyota Super Long Life Coolant” or a similar high quality ethylene glycol
based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid
organic acid technology.
“Toyota Super Long Life Coolant” is a mixt ure of 50% coolant and 50% deionized water.
(Minimum temperature: -35 C [-31 F])
For more details about coolant, contact an y authorized Lexus retailer or Lexus autho-
rized repairer, or any reliable repairer.
■If the coolant level drops within a short time of replenishing
Visually check the radiator, hoses, engine/p ower control unit coolant reservoir caps,
drain cock and water pump.
If you cannot find a leak, have any authorized Lexus retailer or Lexus authorized repairer,
or any reliable repairer, test the cap an d check for leaks in the cooling system.
WARNING
■When the hybrid system is hot
Do not remove the engine/power control un it coolant reservoir caps or the coolant
inlet cap. ( P. 540)
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing serious injuries, such as burns.
NOTICE
■When adding coolant
Coolant is neither plain water nor straight antifreeze. The correct mixture of water and
antifreeze must be used to provide proper lubrication, corrosion protection and cool-
ing. Be sure to read the antifreeze or coolant label.
■If you spill coolant
Be sure to wash it off with water to prevent it from damaging parts or paint.

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7-2. Steps to take in an emergency
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When trouble arises
GS450h_300h_OM_OM30F92E_(EE) Carrying out the corresponding action turns the messages off.
Air conditioning, heater and other operations are tem-
porarily limited due to high power consumption 
Turn off unnecessary electronic equipment to
reduce power consumption.
Please wait until the power supply returns to nor-
mal.
If this item is frequently displayed, have the vehicle
inspected by any authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer imme-
diately.
(If equipped)
Indicates that part of the PC S (Pre-Crash Safety system)
sensor is dirty, covered with ice, etc.
A buzzer also sounds.
 Remove any dirt, ice, etc.
Other displayed messages
Warning messageDetails/Actions
(Flashes)
(Flashes)
Warning messageDetails/Actions
Maintenance of the hybrid battery (traction battery)
cooling component is required
The filter may be clogged, the air intake vent may be
blocked or there may be a gap in the duct.
 Have maintenance performed on the hybrid battery
(traction battery) cooling component at any autho-
rized Lexus retailer or Lexus authorized repairer, or
any reliable repairer.

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 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, 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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7-2. Steps to take in an emergency
When trouble arises
GS450h_300h_OM_OM30F92E_(EE)
If your vehicle overheats
●The needle of the engine coolant temperature gauge ( P. 104) enters the
red zone or a loss of hybrid system power 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 Output Power” ( P. 466) 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
or “Engine Coolant Temp High Stop in a Safe Place See Owner’s Manual” is
shown on the multi-information display
Stop the vehicle in a safe place and turn 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
cooling system for 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 following may indicate that your vehicle is overheating.
Correction procedures
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537
7-2. Steps to take in an emergency
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When trouble arises
GS450h_300h_OM_OM30F92E_(EE) 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 op
erating 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 immediately and contact any authorized Lexus
retailer or Lexus authorized repairer, or any reliable repairer.
If the fans are operating:
Have the vehicle inspected at the nearest any authorized Lexus retailer or
Lexus authorized repairer, or any reliable repairer.
■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 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 retailer or Lexus
authorized repairer, or any reli-
able repairer.
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5407-2. Steps to take in an emergency
GS450h_300h_OM_OM30F92E_(EE)
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 h ood, 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 indi cator on the power
switch and the “READY” indicator are off.
When the hybrid system is 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 fan, which may lead to fingers or clothing
(especially a tie, a scarf or a muffler) getting caught, resulting in serious injury.
●Do not loosen the coolant inlet cap or the
coolant reservoir caps while the hybrid sys-
tem and radiator are hot.
High temperature steam or coolant could
spray out.GS450h
GS300h

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7-2. Steps to take in an emergency
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When trouble arises
GS450h_300h_OM_OM30F92E_(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 additive.