ECU LEXUS RX450h 2021 Workshop Manual

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.

1714-1. Before driving
4
Driving
WARNING
●Do not stack cargo and luggage in the
luggage compartment higher than the
seatbacks.
●When you fold down the rear seats,
long items should not be placed
directly behind the front seats.
●Never allow anyone to ride in the lug-
gage compartment. It is not designed
for passengers. They should ride in
their seats with their seat belts prop-
erly fastened.
●Do not place cargo or luggage in or on
the following locations.
• At the feet of the driver
• On the front passenger or rear seats (when stacking items)
• On the luggage cover
• On the instrument panel
•On the dashboard
●Secure all items in the occupant com-
partment.
■Capacity and distribution
●Do not exceed the maximum axle
weight rating or the total vehicle
weight rating.
●Even if the total load of occupant’s
weight and the cargo load is less than
the total load capacity, do not apply the
load unevenly. Improper loading may
cause deterioration of steering or
braking control which may cause
death or serious injury.
■Roof luggage carrier precautions
Observe the following precautions:
●Place the cargo so that its weight is dis-
tributed evenly between the front and
rear axles.
●If loading long or wide cargo, never
exceed the vehicle overall length or
width. (
P.460)
●Before driving, make sure the cargo is
securely fastened on the roof luggage
carrier.
●Loading cargo on the roof luggage
carrier will make the center of gravity
of the vehicle higher. Avoid high
speeds, sudden starts, sharp turns,
sudden braking or abrupt maneuvers,
otherwise it may result in loss of con-
trol or vehicle rollover due to failure to
operate this vehicle correctly and
result in death or serious injury.
●If driving for a long distance, on rough
roads, or at high sp eeds, stop the vehi-
cle now and then during the trip to
make sure the cargo remains in its
place.
●Do not exceed 165 lb. (75 kg) cargo
weight on the roof luggage carrier.
NOTICE
■When loading cargo (vehicles with a
moon roof or panoramic moon roof)
Be careful not to scratch the surface of
the moon roof or panoramic moon roof.

1744-1. Before driving
for a more safe trailer hookup, the trailer
ball setup must be the proper height for the
coupler on the trailer.Coupler
Trailer ball
■Before towing
Check that the following conditions are
met:
●Ensure that your vehicle’s tires are prop-
erly inflated. ( P.466)
●Trailer tires are inflated according to the
trailer manufacturer’s recommendation.
●All trailer lights work as required by law.
●All lights work each time you connect
them.
●The trailer ball is set at the proper height
for the coupler on the trailer.
●The trailer is level when it is hitched.
Do not drive if the trailer is not level, and
check for improper tongue weight, over-
loading, worn suspension, or other possi-
ble causes.
●The trailer cargo is securely loaded.
●The rear view mirrors conform to all
applicable federal, state/provincial or local regulations. If they do not, install
rear view mirrors appropriate for towing
purposes.
■Adaptive Variable Suspension System
(if equipped)
The suspension can be switched for
improvement in driveability. ( P.284)
■Break-in schedule
If your vehicle is new or equipped with any
new power train components (such as an
engine, hybrid transmission, rear differential
or wheel bearing), Lexus recommends that
you do not tow a trailer until the vehicle has
been driven for over 500 miles (800 km).
After the vehicle has been driven for over
500 miles (800 km), you can start towing.
However, for the next 500 miles (800 km),
drive the vehicle at a speed of less than 50
mph (80 km/h) when towing a trailer, and
avoid full throttle acceleration.
■Maintenance
●If you tow a trailer, your vehicle will
require more frequent maintenance due
to the additional load. (See “Warranty
and Services Guide”, “Owner’s Manual
Supplement” or “Scheduled Mainte-
nance”.)
●Retighten the fixing bolts of the towing
ball and bracket after approximately 600
miles (1000 km) of trailer towing.
■If trailer sway occurs
One or more factors (crosswinds, passing
vehicles, rough roads, etc.) can adversely
affect handling of your vehicle and trailer,
causing instability.
●If trailer swaying occurs:
• Firmly grip the steering wheel. Steer straight ahead.
Do not try to control trailer swaying by
turning the steering wheel.
• Begin releasing th e accelerator pedal
immediately but very gradually to reduce
speed.
Do not increase speed. Do not apply
vehicle brakes.
If you make no extreme correction with the
steering or brakes, your vehicle and trailer
should stabilize. (if enabled, Trailer Sway
Control can also help to stabilize the vehicle
A
B

1764-1. Before driving
■GCWR (Gross Combination
Weight Rating)
The maximum allowable gross combi-
nation weight. The gross combination
weight is the sum of the total vehicle
weight (including the occupants, cargo
and any optional equipment installed
on the vehicle) and the weight of the
trailer being towed (including the
cargo in the trailer).
■GVWR (Gross Vehicle Weight
Rating)
The maximum allowable gross vehicle
weight. The gross vehicle weight is the
total weight of the vehicle. When tow-
ing a trailer, it is the sum of the vehicle
weight (including the occupants, cargo
and any optional equipment installed
on the vehicle) and the tongue weight.
WARNING
●Vehicle-trailer instabil ity is more likely
on steep long downhills. Before
descending steep or long downhill
grades, slow down and downshift. Do
not make sudden downshifts when
descending steep or long downhill
grades. Avoid holding the brake pedal
down too long or applying the brakes
too frequently. This could cause the
brakes to overheat and result in
reduced braking efficiency.
●Do not tow a trailer when the compact
spare tire is installed on your vehicle.
■When towing a trailer
Lexus recommends trailers with brakes
that conform to any applicable federal
and state/provincial regulations.
●If the gross trailer weight exceeds
unbraked TWR, trailer brakes are
required. Lexus recommends trailers
with brakes that conform to all applica-
ble federal and state/provincial regula-
tions.
●Never tap into your vehicle’s hydraulic
system, as this will lower the vehicle’s
braking effectiveness.
●Never tow a trailer without using a
safety chain securely attached to both
the trailer and the vehicle. If damage
occurs to the coupling unit or hitch
ball, there is danger of the trailer wan-
dering into another lane.
NOTICE
■When installing a trailer hitch
Use only the position recommended by
your Lexus dealer. Do not install the
trailer hitch on the bumper; this may
cause body damage.
■Do not directly splice trailer lights
Do not directly splice trailer lights.
Directly splicing trailer lights may dam-
age your vehicle’s electrical system and
cause a malfunction.
Towing related terms

1844-2. Driving procedures
4-2.Driving procedures
1Check that the parking brake is set.
2 Check that the shift lever is in P.
3 Firmly depress the brake pedal.
and a message will be displayed on
the multi-information display.
If it is not displayed, the hybrid system can-
not be started.
4 Press the power switch shortly and
firmly.
When operating the power switch, one
short, firm press is enough. It is not neces-
sary to press and hold the switch.
If the “READY” indicator turns on, the
hybrid system will operate normally.
Continue depressing the brake pedal until
the “READY” indicator is illuminated.
The hybrid system can be started from any
power switch mode.
5Check that the “READY” indicator
is illuminated.
The vehicle will not move when the
“READY” indicator is off.
■Power switch illumination
According to the situation, the power
switch illumination operates as follows.
●When a door is opened, or the power
switch mode is changed from ACCES-
SORY or ON mode to off, the power
switch illumination slowly blinks.
●When depressing the brake pedal with
carrying the electronic key on your per-
son, the power switch illumination rapidly
blinks.
●When the power switch is in ACCES-
SORY or ON mode, the power switch
illumination illuminates.
■If the hybrid system does not start
●The immobilizer system may not have
been deactivated. ( P.73)
Contact your Lexus dealer.
●Check that the shift leve r is securely set in
P. The hybrid system may not start if the
shift lever is displaced out of P. “To Start
Vehicle, Put Shift Lever into P” will be dis-
played on the multi-information display.
●If the door is unlock ed with the mechani-
cal key, the hybrid system cannot be
started using the sm art access system
with push-button start. Refer to P.448to
start the hybrid system. However, if the
electronic key is carried inside the vehicle
and the doors are locked ( P.111), the
hybrid system can be started.
■When the ambient temperature is low,
such as during winter driving conditions
When starting the hybrid system, the flash-
ing time of the “READY” indicator may be
long. Leave the vehicle as it is until the
“READY” indicator is steady on, as steady
means the vehicle is able to move.
■Sounds and vibrations specific to a
hybrid vehicle
 P.67
Power (ignition) switch
Performing the following opera-
tions when carryin g the electronic
key on your person starts the hybrid
system or changes power switch
modes.
Starting the hybrid system

2024-3. Operating the lights and wipers
once.
You can flash the high beams with the
headlights on or off.
AFS (Adaptive Front-lighting System)
secures excellent visibility at intersec-
tions and on curves by automatically
adjusting the direction of the light axis
of the headlights according to vehicle
speed and the degree of the tire’s angle
as controlled by steering input.
AFS operates at speeds of 6 mph (10
km/h) or higher.
■Customization
Some functions can be customized.
(  P.480)
 When the steering wheel or turn
signal lever is operated while the
headlights are on (low beam), a cor-
nering light will turn on and light up
the direction of movement of the
vehicle. The cornering lights are
designed to ensure excellent visibil-
ity when making a turn at an inter-
section.
However, when vehicle speed is approxi-
mately 22 mph (35 km/h) or higher, the
cornering lights will not turn on.
 When the shift lever is in R while the
headlights are on (low beam), both
cornering lights will turn on. This is
designed to enhance visibility when
parking.
■Cornering lights (if equipped)
When the cornering lights are on for more
than 30 minutes, they will turn off automati-
cally.
AFS (Adaptive Front-lighting
System) (if equipped)
Cornering lights (if equipped)

2064-3. Operating the lights and wipers
*:If equipped
1 (U.S.A.) or (Canada)
Turns the fog lights off
2 Turns the fog lights on
■Fog lights can be used when
The headlights are on in low beam.
Operate the lever operates the
wipers or washer as follows.
When “AUTO” is selected, the wipers
will operate automatically when the
sensor detects falling rain. The system
automatically adjusts wiper timing in
accordance with rain volume and vehi-
cle speed.
The sensor sensitivity can be adjusted
when “AUTO” is selected.
Fog light switch*
The fog lights secu re excellent visi-
bility in difficult driving conditions,
such as in rain and fog.
Operating instructions
Windshield wipers and
washer
Operating the lever can switch
between automatic operation and
manual operation, or can use the
washer.
NOTICE
■When the windshield is dry
Do not use the wipers, as they may dam-
age the windshield.
Operating the wiper lever

2114-4. Refueling
4
Driving
4-4.Refueling
Close all the doors and windows,
and turn the power switch off.
 Confirm the type of fuel.
■Fuel types
 P.469
■Fuel tank opening for unleaded gasoline
To help prevent incorrect fueling, your vehi-
cle has a fuel tank opening that only accom-
modates the special nozzle on unleaded
fuel pumps.
Opening the fuel tank cap
The fuel tank of your vehicle has a
special structure, which requires a
reduction in fuel tank pressure
before refueling. After the opener
switch has been pressed, it will take
several seconds until the vehicle is
ready for refueling.
Before refueling the vehicle
WARNING
■When refueling the vehicle
Observe the following precautions while
refueling the vehicle. Failure to do so may
result in death or serious injury.
●After exiting the vehicle and before
opening the fuel door, touch an
unpainted metal surface to discharge
any static electricity. It is important to
discharge static electricity before refu-
eling because sparks resulting from
static electricity can cause fuel vapors
to ignite while refueling.
●Always hold the grips on the fuel tank
cap and turn it slowly to remove it.
A whooshing sound may be heard
when the fuel tank cap is loosened.
Wait until the sound cannot be heard
before fully removing the cap. In hot
weather, pressurized fuel may spray
out of the filler neck and cause injury.
●Do not allow anyone that has not dis-
charged static electricity from their
body to come close to an open fuel
tank.
●Do not inhale vaporized fuel.
Fuel contains substances that are
harmful if inhaled.
●Do not smoke while refueling the vehi-
cle.
Doing so may cause the fuel to ignite
and cause a fire.
●Do not return to the vehicle or touch
any person or object that is statically
charged.
This may cause static electricity to
build up, resulting in a possible ignition
hazard.
■When refueling
Observe the following precautions to
prevent fuel overflowing from the fuel
tank:
●Securely insert the fuel nozzle into the
fuel filler neck.
●Stop filling the tank after the fuel noz-
zle automatically clicks off.
●Do not top off the fuel tank.
NOTICE
■Refueling
●Finish refueling within 30 minutes. If
more than 30 minutes passes, the
internal valve closes. In this condition,
fuel may overflow during the refueling
process.
Press the fuel filler door opener switch
again.

2124-4. Refueling
1Press the switch to open the fuel
filler door.
The fuel filler door will open within about
10 seconds of the sw itch being pressed.
Before refueling is possible, a message will
be shown on the multi-information display
in the instrument clus ter to indicate the
progress of the fuel filler door opener.
2 Open the fuel filler door until it is
securely locked.
3 Turn the fuel tank cap slowly and
remove it, then put it into the holder
on the fuel filler door.
■If the fuel filler door cannot be opened
 P.446
1 After refueling, turn the fuel tank
cap until you hear a click. Once the
cap is released, it will turn slightly in
the opposite direction.
2 Close the fuel filler door.
NOTICE
●Do not spill fuel during refueling.
Doing so may damage the vehicle,
such as causing the emission control
system to operate abnormally or dam-
aging fuel system components or the
vehicle’s painted surface.
Opening the fuel tank cap
NOTICE
■When refueling
When refueling your vehicle, make sure
that the fuel filler door lock is not pushed
by the fuel nozzle boot, etc., as this may
cause a valve to close, possibly resulting
in a fuel spill.
If the fuel filler door lock has been
pushed, operate the fuel filler door
opener switch in the vehicle before con-
tinuing to refuel.
Closing the fuel tank cap

2524-5. Using the driving support systems
the farther away the vehicle will be detected, causing the outside rear view mirror indi-
cator to illuminate or flash.
■The Blind Spot Monitor is operational
when
The Blind Spot Monitor is operational when
all of the following conditions are met:
●The Blind Spot Monitor is on.
●The shift lever is in a position other than R.
●The vehicle speed is greater than approx-
imately 10 mph (16 km/h).
■The Blind Spot Monitor will detect a
vehicle when
The Blind Spot Monitor will detect a vehicle
present in the detection area in the follow-
ing situations:
●A vehicle in an adj acent lane overtakes
your vehicle.
●You overtake a vehicle in an adjacent lane
slowly.
●Another vehicle enters the detection
area when it changes lanes.
■Conditions under wh ich the Blind Spot
Monitor will not detect a vehicle
The Blind Spot Monitor is not designed to
detect the following types of vehicles and/or
objects:
●Small motorcycles, bicycles, pedestrians,
etc.*
●Vehicles traveling in the opposite direc-
tion
●Guardrails, walls, signs, parked vehicles
and similar stationary objects*
●Following vehicles th at are in the same
lane*
●Vehicles traveling 2 lanes away from your
vehicle*
●Vehicles which are being overtaken rap-
idly by your vehicle*
*
: Depending on the conditions, detection of a vehicle and/or object may occur.
■Conditions under which the Blind Spot
Monitor may not function correctly
●The Blind Spot Monitor may not detect
vehicles correctly in the following situa-
tions:
• When the sensor is misaligned due to a
strong impact to the sensor or its sur-
rounding area
• When mud, snow, ice, a sticker, etc. is
covering the sensor or surrounding area
on the rear bumper
• When driving on a road surface that is
wet with standing water during bad
weather, such as heavy rain, snow, or fog
• When multiple vehicles are approaching
with only a small gap between each vehi-
cle
• When the distance between your vehicle
and a following vehicle is short
• When there is a significant difference in speed between your vehicle and the vehi-
cle that enters the detection area
• When the difference in speed between your vehicle and another vehicle is
changing
• When a vehicle enters a detection area traveling at about the same speed as your
vehicle
• As your vehicle starts from a stop, a vehi- cle remains in the detection area
• When driving up and down consecutive steep inclines, such as hills, dips in the
road, etc.
• When driving on roads with sharp bends, consecutive curves, or uneven surfaces
• When vehicle lanes are wide, or when
driving on the edge of a lane, and the
vehicle in an adjacent lane is far away
from your vehicle
• When an accessory (such as a bicycle carrier) is installed to the rear of the vehi-
cle
• When there is a significant difference in height between your vehicle and the
vehicle that enters the detection area
• Immediately after the Blind Spot Monitor
is turned on
●Instances of the Blind Spot Monitor
unnecessarily detecting a vehicle and/or
object may increase in the following situ-