overheating LEXUS RX450h 2021 Owners Manual

13Pictorial index
Precautions for winter season .......................................................................................P.291
To prevent freezing (windshield wiper de-icer)
*.................................................... P.311
Precautions for car wash ............................................................................................... P.357
Fuel filler door ........................................................................................................... P.211
Refueling method ............................................................................................................... .P.211
Fuel type/fuel tank capacity ...... ................................................................................... P.462
Tires.......................................................................................................................... .P.380
Tire size/inflation pressure ............................ ................................................... P.380, 466
Winter tires/tire chains ....................................................................................................P.2 91
Checking/rotation/tire pressure warning system............................................. P.380
Coping with flat tires........................................................................................................ P .432
Hood ..........................................................................................................................P.369
Opening ........................................................................................................................ ....... P.369
Engine oil ..................................................................................................................... ......... P.463
Coping with overheating ............................................................................................... P.454
Warning messages .......................................................................................................... P.428
Headlights/front turn signal lights/front side marker lights ........... P.194, 200
Side turn signal lights ............................................................................................. P.194
Parking lights/daytime running lights............................................................. P.200
Fog lights/cornering lights
*.....................................................................P.200, 206
Rear side marker lights ....................................................................................... P.200
Stop/tail lights ........................................................................................................ P.200
Back-up lights/rear turn signal lights ..................................................... P.194, 200
Shifting the shift lever to R ................................................................................................ P. 191
License plate lights ............................................................................................... P.200
*:If equipped
Light bulbs of the exterior lights for driving
(Replacing method: P.399, Watts: P.468)
E
F
G
H
I
J
K
L
M
N
O

721-4. Hybrid system
Air intake vents
Air discharge vents (RX450h)
When a certain level of impact is
detected by the impact sensor, the
emergency shut off system blocks the
high voltage current and stops the fuel pump to minimize the risk of electrocu-
tion and fuel leakage. If the emergency
shut off system activates, your vehicle
will not restart. To restart the hybrid
system, contact your Lexus dealer.
A message is automatically displayed
when a malfunction occurs in the
hybrid system or an improper opera-
tion is attempted.
If a warning message is shown on the
multi-information display, read the
message and follow the instructions.
(
P.428)
■If a warning light comes on, a warning
message is displayed, or the 12-volt bat-
tery is disconnected
The hybrid system may not start. In this
case, try to start the system again. If the
“READY” indicator does not come on, con-
tact your Lexus dealer.
NOTICE
■Hybrid battery (traction battery) air
intake/discharge vents
●Do not place objects that will block the
air intake vents. The hybrid battery
(traction battery) may overheat and be
damaged.
●Clean the air intake/discharge vents
regularly to prevent the hybrid battery
(traction battery) from overheating.
●Do not get water or foreign materials
in either the air in take/discharge vents
as this may cause a short circuit and
damage the hybrid battery (traction
battery).
Emergency shut off system
A
B
Hybrid warning message

872-1. Instrument cluster
2
Vehicle status information and indicators
■Display items
 Odometer
Displays the total distance the vehicle has
been driven.
Trip meter A/trip meter B
Displays the distance the vehicle has been
driven since the meter was last reset. Trip
meters A and B can be used to record and
display different distances independently.
 Distance until next engine oil
change
Displays the distance the vehicle can be
driven until an oil change is necessary.
■Changing the display
Each time the “ODO TRIP” switch is
pressed, the displayed item will be changed. When the trip meter is dis-
played, pressing and holding the switch
will reset the trip meter.
■Pop-up display
Distance until next engine oil change
Displays the distance until the next engine
oil change. This display will be displayed in
the following situations:
 When the power switch is turned to
ON mode.
 When a warning message indicating
that oil maintenance should be per-
formed soon or is required is dis-
played.
The brightness of the instrument panel
lights can be adjusted.
If the brightness is adjusted when the sur-
roundings are bright and the tail lights are
on (day mode bright ness adjustment), the
brightness level of night mode will be
adjusted at the same time.
WARNING
For example, there is a lag between the
driver’s shifting and the new gear number
appearing on the display. This lag could
cause the driver to downshift again,
causing rapid and excessive engine brak-
ing and possibly an accident resulting in
death or injury.
NOTICE
■To prevent damage to the engine and
its components
●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, imme-
diately stop the vehicle in a safe place,
and check the engine after it has
cooled completely. ( P.454)
Odometer and trip meter dis-
play
Changing the instrument panel
light brightness

1684-1. Before driving
WARNING
●Always apply the parking brake, shift
the shift lever to P, stop the hybrid sys-
tem and lock the vehicle.
Do not leave the vehicle unattended
while the “READY” indicator is illumi-
nated.
If the vehicle is parked with the shift
lever in P but the parking brake is not
set, the vehicle may start to move, pos-
sibly leading to an accident.
●Do not touch the exhaust pipes while
the “READY” indicator is illuminated
or immediately after turning the hybrid
system off.
Doing so may cause burns.
■When taking a nap in the vehicle
Always turn the hybrid system off. Other-
wise, if you accidentally move the shift
lever or depress the accelerator pedal,
this could cause an accident or fire due
to hybrid system overheating. Addition-
ally, if the vehicle is parked in a poorly
ventilated area, exhaust gases may col-
lect and enter the ve hicle, 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 vehi-
cle.
●If the electronically controlled brake
function does not operate, do not fol-
low other vehicles closely and avoid
hills or sharp turns that require brak-
ing.
In this case, braking is still possible, but
the brake pedal should be depressed
more firmly than usual. Also, the brak-
ing distance will increase. Have your
brakes fixed immediately.
●The brake system consists of 2 or more
individual hydraulic systems; if one of
the systems 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 excessively when
any of the tires is up in the air, or the vehi-
cle is stuck in sand, mud, etc. This may
damage the driveline components or
propel the vehicle 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 the hybrid
system output.
●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
Always set the parking brake and shift
the shift lever to P. Failure to do so may
cause the vehicle to move or the vehicle
may accelerate suddenly if the accelera-
tor 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 on the road,
drive as slowly as possible to avoid
damaging the wheels, underside of the
vehicle, etc.

1824-1. Before driving
frequently. This could cause the
brakes to overheat and result in
reduced braking efficiency.
 Due to the added load of the trailer,
your vehicle’s engine may overheat
on hot days (at temperatures over
85°F [30°C]) when driving up a
long or steep grade. If the engine
coolant temperature gauge indi-
cates overheating, immediately turn
off the air conditioning (if in use),
pull your vehicle off the road and
stop in a safe spot. ( P.454)
 Always place wheel blocks under
both the vehicle’s and the trailer’s
wheels when parking. Put the trans-
mission in P and apply the parking
brake. Avoid parking on a slope, but
if unavoidable, do so only after per-
forming the following:
1 Apply the brakes and keep them
applied.
2 Have someone place wheel blocks
under both the vehicle’s and trailer’s
wheels.
3 When the wheel blocks are in
place, release the brakes slowly
until the blocks absorb the load.
4 Shift into P and apply the parking
brake.
5 Turn off the hybrid system.
 When restarting after parking on a
slope:
1 With the transmission in P, start the
hybrid system. Be sure to keep the
brake pedal depressed. 2
Shift into a forward gear. If revers-
ing, shift into R.
3 If the parking brake is in manual
mode, release the parking brake.
(P.195)
4 Release the brake pedal, and slowly
pull or back away from the wheel
blocks. Stop and apply the brakes.
5 Have someone retrieve the blocks.

1854-2. Driving procedures
4
Driving
■Electronic key battery depletion
 P.106
■Conditions affe cting operation
 P.126
■Note for the entry function
 P.127
■Steering lock function
●After turning the power switch off and
opening and closing the doors, the steer-
ing wheel will be lock ed due to the steer-
ing lock function. Operating the power
switch again automatically cancels the
steering lock.
●When the steering lock cannot be
released, “Steering Wheel Lock Press
Power Switch while Turning Wheel” will
be displayed on the multi-information dis-
play.
Check that the shift leve r is in P. Press the
power switch shortly and firmly while
turning the steering wheel left and right.
●To prevent the steering lock motor from
overheating, operation of 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 about
10 seconds, the stee ring lock motor will
resume functioning.
■When “Access System with Elec. Key
Malfunction See Owner’s Manual” is
displayed on the mu lti-information dis-
play
The system may be malfunctioning. 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 vehi-
cle, contact your Lexus dealer immediately.
■If the hybrid system
is malfunctioning
 P.72
■Electronic key battery
 P.393
■Operation of the power switch
●If the switch is no t 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 seconds
before restarting the hybrid system.
■Customization
If the smart access system with push-button
start has been deactivated in a customized
setting, refer to P.447.
WARNING
■When starting the hybrid system
Always start the hybrid system while sit-
ting in the driver’s seat. Do not depress
the accelerator pedal while starting the
hybrid system under any circumstances.
Doing so may cause an accident result-
ing in death or serious injury.
WARNING
■Caution while driving
If hybrid system failure occurs while the
vehicle is moving, do not lock or open the
doors until the vehicle reaches a safe and
complete stop. Activation of the steering
lock in this circumstance may lead to an
accident, resulting in death or serious
injury.

1974-2. Driving procedures
4
Driving
■If “Parking Brake Overheated Parking
Brake Unavailable” is displayed on the
multi-information display
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.
■If “EPB Activation Stopped Incom-
pletely” or “Parking Brake Unavailable”
is displayed on th e multi-information
display
Operate the parking brake switch. If the
message does not disappear after operat-
ing the switch several times, the system may
be malfunctioning. Have the vehicle
inspected by your Lexus dealer immedi-
ately.
■Parking brake operation sound
When the parking brake operates, a motor
sound (whirring sound) may be heard. This
does not indicate a malfunction.
■Parking brake indicator light and park-
ing brake light
●Depending on the power switch mode,
the parking brake in dicator light and
parking brake light will turn on and stay
on as described below:
ON mode: Comes on until the parking
brake is released.
Not in ON mode: Stays on for approxi-
mately 15 seconds.
●When the power switch is turned off with
the parking brake set, the parking brake
indicator light and parking brake light will
stay on for about 15 seconds. This does
not indicate a malfunction.
■Changing the mode
When changing the automatic mode on/off,
the message will be shown on the
multi-information display and the buzzer
sounds.
■Parking the vehicle
 P.164
■Parking brake engaged warning buzzer
A buzzer will sound if the vehicle is driven
with the parking brake engaged. “Release Parking Brake” is displayed on the
multi-information display.
■Warning messages and buzzers
Warning messages and buzzers are used to
indicate a system malfunction or to inform
the driver of the need for caution. If a warn-
ing message is shown on the multi-informa-
tion display, read the message and follow
the instructions.
■If the brake system warning light comes
on
 P.418
■Usage in winter time
 P.293
WARNING
■When parking the vehicle
Do not leave a child in the vehicle alone.
The parking brake may be released unin-
tentionally and there is the danger of the
vehicle moving that may lead to an acci-
dent resulting in death or serious injury.
■Parking brake switch
Do not set any objects near the parking
brake switch. Objects may interfere with
the switch and may lead the parking
brake to unexpectedly operate.
NOTICE
■When parking the vehicle
Before you leave the vehicle, shift the
shift lever to P, set the parking brake 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.

1984-2. Driving procedures
Turns the brake hold system on
The brake hold standby indicator (green) comes on. While the system is holding
the brake, the brake hold operated indica-
tor (yellow) comes on.
■Brake hold system operating conditions
The brake hold system cannot be turned on
in the following conditions:
●The driver’s door is not closed.
●The driver is not wearing the seat belt.
If any of the conditions above are detected
when the brake hold system is enabled, the
system will turn off and the brake hold
standby indicator light will go off. In addi-
tion, if any of the conditions are detected
while the system is holding the brake, a
warning buzzer will sound and a message
will be shown on the multi-information dis-
NOTICE
■When the parking brake cannot be
released due to a malfunction
Driving the vehicle with the parking
brake set will lead to brake components
overheating, which may affect braking
performance and increase brake wear.
Have the vehicle inspected by your
Lexus dealer immediately if this occurs.
Brake Hold
The brake hold system keeps the
brake applied when the shift lever is
in D, S or N with the system on and
the brake pedal has been
depressed to stop the vehicle. The
system releases the brake when the
accelerator pedal is depressed with
the shift lever in D or S to allow
smooth start off.
Enabling the system
A
B

3195-3. Using the air conditioning system and defogger
5
Interior features
Vehicles with seat ventilators
When any switch is pressed, the system
is set to automatic mode and the
“AUTO” indicator (green) lights up.
Each time the switch is pressed, the
operation condition changes as fol-
lows.
Hi (3 segments lit) Mid (2 segments
lit)  Lo (1 segment lit) Off
The level indicator (amber) lights up
during operation.
■Second-row seats
Each time the switch is pressed, the
operation condition changes as fol-
lows.
Hi (3 segments lit) Mid (2 segments
lit)  Lo (1 segment lit) Off
The level indicator (amber) lights up
during operation.
■Operation condition
The power switch is in ON mode.
■When the air conditioning system is
operating in front seat concentrated air-
flow mode (S-FLOW)
If a passenger is not detected in the front
passenger seat, the seat heater of the front
passenger’s seat will be turned off if on.
(  P.312)
■Customization
Some functions can be customized.
(  P.480)
When any switch is pressed, the system
is set to automatic mode and the
“AUTO” indicator (green) lights up.
Each time the switch is pressed, the
operation condition changes as fol-
lows.
Hi (3 segments lit) Mid (2 segments
A
B
A
WARNING
■To prevent overheating and minor
burn injuries
Observe the following precautions when
using the seat heaters.
●Do not cover the seat with a blanket or
cushion when using the seat heater.
●Do not use seat heater more than nec-
essary.
Seat ventilators (front seats)
A

4547-2. Steps to take in an emergency
“Engine Coolant Temp High Stop in
a Safe Place See Owner’s Manual”
is shown on the multi-information
display
1 Stop the vehicle in a safe place and
turn off the air conditioning system,
and then stop the hybrid system.
2 If you see steam:
Carefully lift the hood after the
steam subsides.
If you do not see steam:
Carefully lift the hood.
3 After the hybrid system has cooled
down sufficiently, inspect the hoses
WARNING
●Make sure to replace the 12-volt bat-
tery with one designed for this vehicle.
Otherwise, hydrogen gas may enter
the vehicle, possibly causing a fire or
explosion.
●After replacing, securely attach the
exhaust hose and exhaust hole plug to
the exhaust hole of the replaced
12-volt battery. If not properly installed,
gases (hydrogen) may leak into the
vehicle interior, and there is the possi-
ble danger of the gas igniting and
exploding.
NOTICE
■When handling jumper cables
When connecting the jumper cables,
ensure that they do not become entan-
gled 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 bat-
tery from another ve hicle in an emer-
gency. It cannot be used to jump start
another vehicle.
If your vehicle overheats
The following may indicate that
your vehicle is overheating.
 The needle of the engine coolant
temperature gauge ( P.83)
enters the red zone, or a loss of
hybrid system power is experi-
enced. (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 Output power
reduced” is shown on the
multi-information display.
 Steam comes out from under the
hood.
Correction procedures