overheating Lexus GS450h 2018 Owner's Manual / LEXUS 2018 GS450H OWNER'S MANUAL (OM30G62U)

731-2. Hybrid system
GS450h_OM_OM30G62U_(U)
1
For safety and security
WARNING
■Hybrid battery (traction battery)
●Never resell, hand over or modify the hybrid battery. To prevent accidents, hybrid
batteries that have been removed from a disposed vehicle are collected through
Lexus dealer. Do not dispose of the battery yourself.
Unless the battery is properly collected, the following may occur, resulting in death
or serious injury:
• The hybrid battery may be illegally dispos ed of or dumped, and it is hazardous to
the environment or someone may touch a high voltage part, resulting in an electric
shock.
• The hybrid battery is intended to be used exclusively with your hybrid vehicle. If the hybrid battery is used outside of your vehicle or modified in any way, accidents
such as electric shock, heat generation , smoke generation, an explosion and elec-
trolyte leakage may occur.
When reselling or handing over your vehicle, the possibility of an accident is
extremely high because the person receiving the vehicle may not be aware of these
dangers.
●If your vehicle is disposed of without the hybrid battery having been removed, there is
a danger of serious electric shock if high voltage parts, cables and their connectors
are touched. In the event that your vehicle must be disposed of, the hybrid battery
must be disposed of by your Lexus dealer or a qualified service shop. If the hybrid bat-
tery is not disposed of properly, it may cause electric shock that can result in death or
serious injury.
NOTICE
■Hybrid battery (traction ba ttery) air intake vents
●Do not place objects that will block the air in take vents. When the air intake vents are
blocked, battery operations will be rest ricted, leading to poor fuel economy.
●Clean the air intake vents regularly to prevent the hybrid battery (traction battery)
from overheating.
●Do not get water or foreign materials in the air intake vents as this may cause a short
circuit and damage the hybrid battery (traction battery).
●Do not carry large amounts of water such as water cooler bottles in the vehicle. If
water spills onto the hybrid battery (tract ion battery), the battery may be damaged.
Have the vehicle inspected by your Lexus dealer.

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GS450h_OM_OM30G62U_(U)
2. Instrument cluster
WARNING
■The information display at low temperatures
Allow the interior of the vehicle to warm up before using the liquid crystal information
display. At extremely low temperatures, th e information display monitor may respond
slowly, and display changes may be delayed.
For example, there is a lag between the dr iver’s shifting and the new gear number
appearing on the display. This lag could ca use the driver to downshift again, causing
rapid and excessive engine braking and possibly an accident resulting in death or
injury.
NOTICE
■To prevent damage to the hybr id system and its components
●While the tachometer is displayed, do not let the indicator needle of the tachometer
enter the red zone, which indicates the maximum engine speed.
●The engine may be overheating if the engine coolant temperature gauge is in the red
zone (H). In this case, immediately stop the vehicle in a safe place, and check the
engine after it has cooled completely. (→ P. 461)

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GS450h_OM_OM30G62U_(U)
4-1. Before driving
WARNING
Observe the following precautions.
Failure to do so may result in death or serious injury.
■When taking a nap in the vehicle
Always turn the hybrid system off. Otherwise, if you accidentally move the shift lever or
depress the accelerator pedal, this could cause an accident or fire due to hybrid system
overheating. Additionally, if the vehicle is parked in a poorly ventilated area, exhaust
gases may collect and enter the vehicle, lead ing to death or a serious health hazard.
■When braking
●When the brakes are wet, drive more cautiously.
Braking distance increases when the brakes are wet, and this may cause one side of
the vehicle to brake differently than the other side. Also, the parking brake may not
securely hold the vehicle.
●If the electronically controlled brake system does not operate, do not follow other
vehicles closely and avoid hills or sharp turns that require braking.
In this case, braking is still possible, bu t the brake pedal should be depressed more
firmly than usual. Also, the braking distan ce will increase. Have your brakes fixed
immediately.
●The brake system consists of 2 or more indi vidual hydraulic systems; if one of the sys-
tems fails, the other(s) will still operate. In this case, the brake pedal should be
depressed more firmly than usual and the braking distance will increase. Have your
brakes fixed immediately.
■If the vehicle becomes stuck
Do not spin the wheels excessive ly when any of the tires is up in the air, or the vehicle is
stuck in sand, mud, etc. This may damage the driveline components or propel the vehi-
cle forward or backward, causing an accident.
NOTICE
■When driving the vehicle
●Do not depress the accelerator and brake pedals at the same time during driving, as
this may restrain hybrid system output.
●Do not use the accelerator pedal or depre ss the accelerator and brake pedals at the
same time to hold the vehicle on a hill.
■When parking the vehicle
Always set the parking brake, and shift the sh ift lever to P. Failure to do so may cause
the vehicle to move or the vehicle may acce lerate suddenly if the accelerator pedal is
accidentally depressed.
■Avoiding damage to vehicle parts
●Do not turn the steering wheel fully in either direction and hold it there for an
extended period of time.
Doing so may damage the power steering motor.
●When driving over bumps in the road, drive as slowly as possible to avoid damaging
the wheels, underside of the vehicle, etc.

GS450h_OM_OM30G62U_(U)
1854-2. Driving procedures
4
Driving
■When the steering lock cannot be released
■Steering lock motor overheating prevention
To prevent the steering lock motor from overheating, the motor may be suspended if the
hybrid system is turned on and off repeatedly in a short period of time. In this case, refrain
from operating the hybrid system. After abou t 10 seconds, the steering lock motor will
resume functioning.
■When “Check Access System with Elec. Key” will be displayed on the multi-informa-
tion display
The system may be malfunctio ning. Have the vehicle inspected by your Lexus dealer
immediately.
■If the “READY” indicator does not come on
In the event that the “READY” indicator does not come on even after performing the
proper procedures for starting the vehicl e, contact your Lexus dealer immediately.
■If the hybrid system is malfunctioning
→P. 410
■If the electronic key battery is depleted
→P. 382
■Operation of the power switch
●If the switch is not pressed shortly and firmly, the power switch mode may not change or
the hybrid system may not start.
●If attempting to restart the hybrid system immediately after turning the power switch off,
the hybrid system may not start in some cases. After turning the power switch off,
please wait a few seco nds before restarting the hybrid system.
■If the smart access system with push-button start has been deactivated in a customized
setting
→ P. 454
“Steering Lock active” will be displayed on the
multi-information display.
Check that the shift lever is set in P. Press the
power switch while turning the steering wheel
left and right.

GS450h_OM_OM30G62U_(U)
1974-2. Driving procedures
4
Driving
■Parking brake operation
●When the power switch is not in ON mode, the parking brake cannot be released using
the parking brake switch.
●When the power switch is not in ON mode , automatic mode (automatic brake setting
and releasing) is not available.
●If the parking brake is operated repeatedly over a short period of time, the system may
restrict operation to prevent overheating. If this happens, refrain from operating the
parking brake. Normal operation will return after about 1 minute.
●In situations such as when parking on a steep slope*, the maximum amount of braking
force can be used by pressing the parking brake switch with the parking brake already
set.
*: Use wheel chocks when parking on a steep slope.
■Parking brake operation sound
When the parking brake operates, a motor so und (whirring sound) may be heard. This
does not indicate a malfunction.
■Parking brake indicator light
●Depending on the power switch mode, the parking brake indicator light will come on
and stay on as described below:
ON mode: Comes on until the parking brake is released.
Not in ON mode: Stays on fo r approximately 15 seconds.
●When the power switch is turned off with th e parking brake set, the parking brake indi-
cator light will stay on for about 15 seconds. This does not in dicate a malfunction.
■When there is a malfunction in the system
Warning lights and/or warning message will turn on or flash. ( →P. 406, 410)
Depending on the condition, the park ing brake indicator light may flash.
■Parking the vehicle
→P. 168
■Parking brake engaged warning buzzer
→P. 416
■Usage in winter time
→P. 277
NOTICE
■When parking the vehicle
Before you leave the vehicle, set the parking brake, shift the shift lever to P and make
sure that the vehicle does not move.
■When the system malfunctions
Stop the vehicle in a safe place and check the warning messages.
■When the parking brake cannot be released due to a malfunction
Use the parking brake release tool to manually release the parking brake. (→P. 452)
Driving the vehicle with the parking brake se t will lead to brake components overheat-
ing, which may affect braking performance and increase brake wear.

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4-5. Using the driving support systems
■ECB operation sound
ECB operating sound may be heard in the following cases, but it does not indicate that a
malfunction has occurred.
●Operating sound heard from the engine compartment when the brake pedal is oper-
ated.
●Motor sounds of the brake system heard from the front part of the vehicle when the
driver’s door is opened.
●Operating sound heard from the engine compartment when one or two minutes
passed after the stop of the hybrid system.
■EPS, VGRS and DRS operation sound
When the steering wheel is operated, a motor sound (whirring sound) may be heard.
This does not indicate a malfunction.
■Automatic reactivation of TRAC and VSC systems
After turning the TRAC and VSC systems off, the systems will be automatically re-
enabled in the following situations:
●When the power switch is turned off
●If only the TRAC system is turned off, the TRAC will turn on when vehicle speed
increases
If both TRAC and VSC systems are turned off, automatic re-enabling will not occur
when vehicle speed increases.
■Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the system from overheating
when there is frequent steering input over an extended period of time. The steering
wheel may feel heavy as a result . Should this occur, refrain from excessive steering input
or stop the vehicle and turn the hybrid system off. The EPS system should return to nor-
mal within 10 minutes.
■Operating conditions of hill-start assist control
When the following four conditions are met, the hill-start assist control will operate;
●The shift lever is in a position other than N or P (when starting off forward/backward on
an upward incline).
●The vehicle is stopped.
●The accelerator pedal is not depressed.
●The parking brake is not engaged.
■Automatic system cancelation of hill-start assist control
The hill-start assist control will be cancel ed in any of the following situations;
●The shift lever is shifted to N or P.
●The accelerator pedal is depressed.
●The parking brake is engaged.
●Approximately 2 seconds elapse after the brake pedal is released.

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GS450h_OM_OM30G62U_(U)5-2. Using the air conditio ning system and defogger
5
Interior features
Heated steering wheel/seat heaters/seat ventila-
tors
Heated steering wheel and seat heaters heat the side grips of the steering
wheel and seats, respectively. Seat ventilators maintain good airflow by blow-
ing air from the seats.
WARNING
●Care should be taken to prevent injury if anyone in the following categories comes in
contact with the steering wheel or seats when the heater is on:
• Babies, small children, the elderly, th e sick and the physically challenged
• Persons with sensitive skin
• Persons who are fatigued
• Persons who have taken alcohol or drugs that induce sleep (sleeping drugs, cold
remedies, etc.)
●Observe the following precautions to pr event the minor burns or overheating:
• Do not cover the seat with a blanket or cushion when using the seat heater.
• Do not use seat heater more than necessary.
NOTICE
●To prevent damage to the seat heaters/seat ventilators, do not put heavy objects that
have an uneven surface on the seat and do not stick sharp objects (needles, nails, etc.)
into the seat.
●To prevent 12-volt battery discharge, do not use the functions when the hybrid system
is off.

4187-2. Steps to take in an emergency
GS450h_OM_OM30G62U_(U)
Indicates that the parking brake system is overheatingA buzzer also sounds.
→ Do not use the parking brake until the message dis-
appears.
Indicates an engine malfunction
A buzzer also sounds.
→ Have the vehicle inspected by your Lexus dealer.
Indicates an engine malfunction
A buzzer also sounds.
→ Have the vehicle inspected by your Lexus dealer.
Indicates a malfunction in:
• The SRS airbag system;
• The front passenger occupa nt classification system;
or,
• The seat belt pretensioner system
A buzzer also sounds.
→ Have the vehicle inspected by your Lexus dealer.
Warning messageDetails/Actions
(U.S.A.) (Canada)
(U.S.A.) (Canada)
(U.S.A.) (Canada)

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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
1
2
3
1
2

530Alphabetical index
GS450h_OM_OM30G62U_(U)
Child restraint system............................ 53Booster seats, definition ....................53
Booster seats, installation....................61
Convertible seats, definition ............ 53
Convertible seats, installation .........59
Front passenger occupant classification system ......................... 46
Infant seats, definition .......................... 53
Infant seats, installation .......................59
Installing CRS with LATCH anchors .................... 58
Installing CRS with seat belts ..........59
Installing CRS with top tether strap ......................... 62
Child safety ................................................ 52 12-volt battery precautions ........................... 363, 460
Airbag precautions ..............................38
Child restraint system ......................... 53
How your child should wear the seat belt ................................... 31, 32
Installing child restraints..................... 57
Moon roof precautions.................... 165
Power window lock switch ............ 160
Power window precautions .......... 162
Rear door child-protectors ........... 125
Removed electronic key battery precautions.............. 383
Seat belt comfort guide .......................31
Seat belt extender precautions ...... 34
Seat belt precautions ..........................56
Seat heater precautions................... 301
Trunk precautions................................. 131 Child-protectors .................................... 125
Cleaning .......................................336, 340
Aluminum wheels .............................. 337
Exterior ................................................... 336
Interior .....................................................340
Seat belts.................................................. 341
Clock........................................................... 315
Coat hooks ............................................. 320
Condenser.............................................. 359
Console box ........................................... 308
Console box light ................................. 309
Consumption screen ..............................112
Coolant .................................................... 358 Capacity................................................. 475
Checking ...............................................358
Preparing and checking before winter.................................................... 276
Cooling system ..................................... 358 Hybrid system overheating ............461
Consumption screen ............................109
Cruise control Cruise control ..................................... 255
Dynamic radar cruise control with full-speed range ................... 243
Cup holders............................................ 309
Curtain shield airbags ............................36
Customizable features .......................494