2018 Lexus GS450h cooling

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GS450h_OM_OM30G62U_(U)
6-3. Do-it-yourself maintenance
WARNING
The engine compartment contains many mechanisms and fluids that may move suddenly,
become hot, or become electrically energize d. To avoid death or serious injury, observe
the following precautions.
■When working on the engine compartment
●Make sure that the “POWER ON” on the multi-information display and the
“READY” indicator are both off.
●Keep hands, clothing and tools away from the moving fan and engine drive belt.
●Be careful not to touch the engine, power co ntrol unit, radiator, exhaust manifold, etc.
right after driving as they may be hot. Oil and other fluids may also be hot.
●Do not leave anything that may burn easily, such as paper and rags, in the engine
compartment.
●Do not smoke, cause sparks or expose an open flame to fuel. Fuel fumes are flamma-
ble.
■When working near the electric cooling fans or radiator grille
Be sure the power switch is off.
With the power switch in ON mode, the electric cooling fans may automatically start to
run if the air conditioning is on and/ or the coolant temperature is high. ( →P. 359)
■Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc. from getting in
your eyes.
NOTICE
■If you remove the air cleaner filter
Driving with the air cleaner f ilter removed may cause excessive engine wear due to dirt
in the air.

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GS450h_OM_OM30G62U_(U)6-3. Do-it-yourself maintenance
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Maintenance and care
Engine compartment
■12-volt battery
→ P. 362
Engine oil level dipstick
(→P. 355)
Engine coolant reservoir (→P. 358)
Engine oil filler cap (→ P. 356)
Power control unit coolant
reservoir ( →P. 358) Brake fluid reservoir
(→P. 360)
Fuse box ( →P. 384)
Washer fluid tank ( →P. 361)
Electric cooling fans
Condenser ( →P. 359)
Radiator (→ P. 359)1
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GS450h_OM_OM30G62U_(U)
6-3. Do-it-yourself maintenance
The coolant level is satisfactory if it is between the “FULL” and “LOW” lines on
the reservoir when the hybrid system is cold.
■Engine coolant reservoir
Reservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW”
line, add coolant up to the “FULL”
line. ( →P. 461)
■Power control unit coolant reservoir
Reservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW”
line, add coolant up to the “FULL”
line. ( →P. 461)
■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.
U.S.A.:
“Toyota Super Long Life Coolant” is a mixt ure of 50% coolant and 50% deionized water.
(Minimum temperature: -31 °F [-35 °C])
Canada:
“Toyota Super Long Life Cool ant” is a mixture of 55% coolant and 45% deionized water.
(Minimum temperature: -44° F [-42°C])
For more details about coolant, contact your Lexus dealer.
■If the coolant level drops within a short time of replenishing
Visually check the radiator, hoses, engine/power control unit coolant reservoir caps,
drain cock and water pump.
If you cannot find a leak, have your Lexus de aler test the cap and check for leaks in the
cooling system.
Coolant
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GS450h_OM_OM30G62U_(U)
3596-3. Do-it-yourself maintenance
6
Maintenance and care
Check the radiator and condenser and clear away any foreign objects.
If either of the above parts is extremely dirty or you are not sure of their condi-
tion, have your vehicle inspected by your Lexus dealer.
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. 465)
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.
Radiator and condenser
WARNING
■When the hybrid system is hot
Do not touch the radiator or condenser as they may be hot and cause serious injuries,
such as burns.

4327-2. Steps to take in an emergency
GS450h_OM_OM30G62U_(U)
Carrying out the corresponding action turns the messages off.
Warning messageDetails/Actions
(If equipped)
Indicates that the PCS (Pre-Collision System) is tempo-
rarily unavailable
→ When conditions improve, the system resumes
operation. If this item is displayed continuously, have
the vehicle inspected by your Lexus dealer.
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 at your Lexus dealer immediately.
(If equipped)
Indicates that part of th e PCS (Pre-Collision System)
sensor is dirty, covered with ice, etc.
A buzzer also sounds.
→ Remove any dirt, ice, etc.
Other displayed messages
(Flashes)
(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 performe d on the hybrid battery
(traction battery) cooling component at your Lexus
dealer.

4607-2. Steps to take in an emergency
GS450h_OM_OM30G62U_(U)
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 cab le 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 yo ur Lexus dealer 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 de trimental to the health of passengers.
■When replacing the 12-volt battery
→P. 364
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 te rminal 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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When trouble arises
7-2. Steps to take in an emergency
If your vehicle overheats
●The needle of the engine coolant temperature gauge ( →P. 88) enters the red
zone or a loss of hybrid system power is experienced. (For example, the vehi-
cle 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. 410) 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 your Lexus
dealer.
The following may indicate that your vehicle is overheating.
Correction procedures
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4627-2. Steps to take in an emergency
GS450h_OM_OM30G62U_(U)
The coolant level is satisfactory if it is between the “FULL” and “LOW” lines
on the reservoir.
Reservoir
“FULL”
“LOW”
Coolant inlet cap
Add coolant if necessary.
(→ P. 464)
Water can be used in an emergency
if engine 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 immediately and contact your Lexus dealer.
If the fans are operating:
Have the vehicle inspected at the nearest Lexus dealer.
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