overheating Lexus HS250h 2011 Do-it-yourself maintenance / LEXUS 2011 HS250H OWNERS MANUAL (OM75037U)

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1-1. Hybrid system
CAUTION
●If your vehicle needs to be towed, do so with front wheels raised. If the wheels
connected to the electric motor (traction motor) are on the ground when towing,
the motor may continue to generate electricity. This may cause an electricity
leakage leading to a fire. (
P. 4 8 9 )
●Carefully inspect the ground under the vehicle. If you find that liquid has leaked
onto the ground, the fuel system may have been damaged. Leave the vehicle as
soon as possible.
■Nickel-metal hydride battery
Your vehicle contains a sealed nickel-metal hydride battery. If disposed of improp-
erly, it is hazardous to the environment and there is a risk of severe burns and elec-
trical shock that may result in death or serious injury.
■Emergency shut off system
Carefully check to see if there are exposed high voltage parts or cables. Never
touch the parts or cables. (
P. 2 8 )
NOTICE
■Hybrid battery air vent
●Do not put foreign objects near the air ve nt. The hybrid battery (traction battery)
may overheat and be damaged.
●Clean the air vent regularly to prevent th e hybrid battery (traction battery) from
overheating.
●Do not wet or allow foreign substances to enter the air vent 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 (traction battery), the battery may be dam-
aged. Have the vehicle inspected by your Lexus dealer.

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2-1. Driving procedures
2
When driving
CAUTION
■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 venti-
lated area, exhaust gases may collect and enter the vehicle, leading 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 power brake assist function does not operate, do not follow other vehicles
closely and avoid downhill or sharp turns that require braking.
In this case, braking is still possible, but it will require more force on the pedal than
usual. Braking distance may also increase.
●The brake system consists of 2 individual hydraulic systems; if one of the systems
fails, the others will still operate. In th is case, the brake pedal should be depressed
more firmly than usual and the braking distance will increase. If this happens, do
not continue to drive the vehicle. If the brake system warning light (red indicator)
comes on while driving, immediately stop the vehicle in a safe place and contact
your Lexus dealer.
NOTICE
■When driving the vehicle
●Do not depress the accelerator and brake pe dals at the same time during driving.
If the brake pedal is depressed whil e driving with the accelerator pedal
depressed, driving torque may be restrained.
●Do not use the accelerator pedal or depress the accelerator and brake pedals at
the same time to hold the vehicle on a hill.
■When parking the vehicle
Be sure to firmly apply the parking brake an d set the shift position to P. Failure to do
so may cause the vehicle to move or the vehicle may accelerate suddenly if the
accelerator pedal is accidentally depressed.

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2-2. Instrument cluster
2
When driving
NOTICE
■To prevent damage to the hybrid system and its components
A high engine coolant temperature warning light (P. 498) is installed instead of
an engine coolant temperature gauge. If the high engine coolant temperature
warning light illuminates or flashes, the vehicle may be overheating. Immediately
stop the vehicle in a safe area ( P. 5 4 8 ) .

380
3-7. Other interior features
CAUTION
■Burns
●Use caution when seating the following persons in a seat with the seat heater on
to avoid the possibility of burns:
• Babies, small children, the elderly, the sick and the physically challenged
• Persons with sensitive skin
• Persons who are fatigued
• Persons who have taken alcohol or dr ugs that induce sleep (sleeping drugs,
cold remedies, etc.)
●Do not cover the seat with anything when using the seat heater.
Using the seat heater with a blanket or cushion increases the temperature of the
seat and may lead to overheating.
●Do not use the seat heater more than necessary. Doing so may cause minor
burns or overheating.
NOTICE
■To prevent damage to the seat heaters/ventilators
Do not put heavy objects that have an unev en surface on the seat and do not stick
sharp objects (needles, nail s, etc.) into the seat.
■To prevent 12-volt battery discharge
Turn the seat heaters/ventilators off when the hybrid system is off.

5
When trouble arises
499
5-2. Steps to take in an emergency
Have the vehicle inspected by your Lexus dealer immediately.Failing to investigate the cause of the following warnings may lead to the
system operating abnormally and possibly cause an accident. Have the
vehicle inspected by your Lexus dealer immediately.
High engine coolant temperatur e warning light (flashes or
comes on) Indicates that the engine is overheating P. 5 4 8
• Flashes: Engine is overheating. Drive carefully.
• Comes on: Engine is overheated. Stop the vehicle.
Warning lightWarning light/Details
Brake system warning light Indicates a malfunction in:
• The regenerative brake system; or
• The electronically controlled brake system
(U.S.A.)

(Canada)
Malfunction indicator lamp
Indicates a malfunction in:
• The hybrid system;
• The electronic engine control system;
• The electronic throttle control system; or
• The hybrid transmission control system
SRS warning lightIndicates a malfunction in:
• The SRS airbag system;
• The front passenger occupant classification system; or
• The seat belt pretensioner system
(U.S.A.)

(Canada)
“ABS” warning lightIndicates a malfunction in:
•The ABS; or
• The brake assist system
Warning lightWarning light/Details

5
When trouble arises
513
5-2. Steps to take in an emergency
(U.S.A. only)
Indicates that the engine
oil should be changedComes on approxi-
mately 5000 miles
(8000 km) after the
engine oil is changed
(and the oil maintenance
data has been reset)
Check and change the
engine oil.
Indicates that the tire
inflation pressure is lowCheck the tire inflation
pressure, and adjust to the
appropriate level.
(If equipped)
Indicates that the pre-
collision system is not
currently functional
because the grille or the
sensor is dirty.
This message also
appears when the pre-
collision system is not
functional due to over-
heating.
Check the grille and the
sensor and clean them if
they are dirty.In case of overheating,
the system will become
functional once the sys-
tem cools down.
(If equipped)
Indicates that intuitive
parking assist sensor is
dirty or covered with ice
A buzzer also sounds.
The site of the malfunc-
tion and the vehicle
image are flashing.
Clean the sensor.
Wa r n i n g m e s s a g eDetailsCorrection procedure

548
5-2. Steps to take in an emergency
If your vehicle overheats
Correction procedures■ If the engine coolant temperature warning light comes on or flashes
Stop the vehicle in a safe place and turn off the air conditioning
system.
Check to see if steam is coming out from the engine area.
If you see steam:
Stop the hybrid system. Carefully lift the hood after the steam
subsides and then restart the hybrid system.
If you do not see steam:
Leave the hybrid system operating and carefully lift the hood.
Check to see if the cooling fans are operating.
If the fans are operating:
Wait until the high engine coolant temperature warning light goes
off and then stop the hybrid system.
If the fans are not operating:
Stop the hybrid system immediately and call your Lexus dealer.
The following may indicate that your vehicle is overheating:
●The high engine coolant temperature warning light comes on or
flashes:
The engine may be overheating.
● “HYBRID SYSTEM OVERHEAT” is sh own on the multi-information
display:
The power control unit may be overheating.
Follow the correction procedure as described below.

550
5-2. Steps to take in an emergency
After the hybrid system has cooled
down, check the power control
unit coolant level and inspect the
cooling system for leaks.
If the engine compartment cover
needs to be removed. (P. 4 2 9 )
Add power control unit coolant if
necessary.
Water can be used in an emer-
gency if power control unit coolant
is unavailable. ( P. 5 6 0 )
Have the vehicle inspected at the ne arest Lexus dealer as soon as possi-
ble.
■Overheating
The following symptoms may occur wh en your vehicle is overheating:
●The high engine coolant temperature warn ing light comes on or flashes, or the
hybrid system output decreases.
●Steam comes out from the engine area.
●“HYBRID SYSTEM OVERHEAT” is displayed on the multi-information display.

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Alphabetical index
Cooling systemEngine overheating .......................... 548
Cruise control Cruise control ..................................... 204
Dynamic radar cruise control .....208
Cup holders.............................................. 371
Curtain shield airbags ..........................106
Customizable features ...................... 580
Daytime running light system............189
Defogger (vehicles without navigation system)Rear window........................................ 264
Side mirrors.......................................... 264
Defogger (vehicles with navigation system)*
Dimensions ............................................. 556
Dinghy towing ....................................... 253
Display Dynamic radar cruise control ................................................. 208
Multi-information display................. 172
Trip information .................................... 175
Warning message ............................ 507
Do-it-yourself maintenance..............422
Door courtesy lights Door courtesy lights ........................ 364
Wattage ................................................. 564 Doors
Door glasses ........................................... 87
Door lock ............................... 45, 55, 58
Rear door child protector ................59
Side doors ............................................... 58
Side mirrors .............................................84
Driver’s seat belt reminder light ...... 501
Driver’s seat position memory ........... 69
Driving Break-in tips .......................................... 139
Correct posture................................... 104
Procedures ............................................ 138
Winter driving tips ............................. 249
Driving position memory ...................... 69
Electric power steering ...................... 229
Electronic key If the electronic key does not operate properly ........................... 540
Emergency, in case of If the electronic key does not operate properly ........................... 540
If the engine will not start................537
If the hybrid system will not start ........................................................537
If the 12-volt battery is discharged .........................................543
If the warning buzzer sounds ..... 498
If the warning light turns on.......... 498
If the warning message is displayed............................................ 507
D
*: Refer to “Navigation System Owner’s Manual”.
E

614
Alphabetical index
If you have a flat tire ......................... 527
If you lose your keys.........................539
If you think something is wrong ...................................................495
If your electronic key does not operate properly ....................540
If your vehicle becomes stuck..... 552
If your vehicle has to be stopped in an emergency .............................554
If your vehicle needs to be towed ...................................................489
If your vehicle overheats ................548
Emergency flasher Switch ..................................................... 488
Engine Accessory mode ................................ 148
Compartment ..................................... 428
Engine switch......................................... 147
Hood........................................................ 425
How to start the engine.................... 147
How to start the hybrid system .................................................... 147
Identification number.......................556
If the engine will not start ............... 537
If the hybrid system will not start........................................................ 537
Ignition switch........................................ 147
Overheating.........................................548
Power switch ......................................... 147
Engine compartment cover ............. 429 Engine coolant
Capacity ................................................ 560
Checking................................................434
Preparing and checking before winter.....................................249
Engine/power control unit coolant Capacity ................................................ 560
Checking................................................434
Preparing and checking before winter.....................................249
Engine immobilizer system ................. 98
Engine oil Capacity ................................................558
Checking............................................... 430
Preparing and checking before winter.....................................249
Engine oil maintenance data ........... 432
Engine switch ........................................... 147
Enhanced VSC ..................................... 229
EPS ............................................................. 229
EV drive mode switch ..........................152
Event data recorder ............................ 496
Floor mat .................................................. 384
Fluid Brake ....................................................... 562
Washer................................................... 438
Fog lights Replacing light bulbs ........................475
Switch ........................................................ 197
Wattage ................................................. 564
F