2020 LEXUS RX450H ECU

6508-2. Steps to take in an emergency
RX350/RX350L_U
■While towing
If the engine is not running, the power assist for the brakes and steering will not function,
marking steering and braking more difficult.
■Wheel nut wrench
Wheel nut wrench is installe d in luggage compartment. ( P. 667)
WARNING
Observe the following precautions.
Failure to do so may result in death or serious injury.
■When towing the vehicle
2WD models
AWD models
■While towing
●When towing using cables or chains, avoid sudden starts, etc. which place excessive
stress on the towing eyelets, cables or chains. The towing eyelets, cables or chains
may become damaged, broken debris ma y hit people, and cause serious damage.
●Do not turn the engine switch off.
There is a possibility that the steering wheel is locked and cannot be operated.
■Installing towing eyelets to the vehicle
Make sure that towing eyel ets are installed securely.
If not securely installed, towing ey elets may come loose during towing.
Be sure to transport the vehicle with the front
wheels raised or with all four wheels raised off
the ground. If the vehicle is towed with the front
wheels contacting the ground, the drivetrain
and related parts may be damaged.
Be sure to transport the vehicle with all four
wheels raised off the ground. If the vehicle is
towed with the tires contacting the ground, the
drivetrain or related parts may be damaged,
the vehicle may fly off the truck.

6518-2. Steps to take in an emergency
8
When trouble arises
RX350/RX350L_U
NOTICE
■To prevent damage to the vehicle when towing using a wheel-lift type truck
●Do not tow the vehicle from the rear when the engine switch is off. The steering lock
mechanism is not strong enough to hold the front wheels straight.
●When raising the vehicle, ensure adequate ground cleara nce for towing at the oppo-
site end of the raised vehicle. Without ad equate clearance, the vehicle could be dam-
aged while being towed.
■To prevent damage to the vehicle wh en towing with a sling-type truck
Do not tow with a sling-type truck, either from the front or rear.
■To prevent damage to the ve hicle during emergency towing
Do not secure cables or chains to the suspension components.
■Recreational towing (behind motor home, etc)
Never dinghy tow your vehicle to prevent caus-
ing serious damage to the Dynamic Torque
Control AWD system (AWD models) and
transmission. ( P. 230)

6578-2. Steps to take in an emergency
8
When trouble arises
RX350/RX350L_U
*1: Driver's and front passenger's seat belt warning buzzer:
The driver’s seat belt warning buzzer sounds to alert the driver that his or her seat belt
is not fastened. Once the engine switch is turned to IGNITION ON mode, the
buzzer sounds for 6 seconds. If the vehicl e reaches a speed of 12 mph (20 km/h), the
buzzer sounds once. If the seat belt is still unfastened after 24 seconds, the buzzer will
sound intermittently for 10 se conds. Then, if the seat belt is still unfastened, the buzzer
will sound in a different to ne for 20 more seconds.
The front passenger’s seat belt warning buzzer sounds to alert the front passenger
that his or her seat belt is not fastened. Th e buzzer sounds once if the vehicle reaches
a speed of 12 mph (20 km/h). If the seat belt is still unfastened after 24 seconds, the
buzzer will sound intermittently for 10 seconds. Then, if the seat belt is still unfastened,
the buzzer will sound in a different tone for 20 more seconds.
*2: Rear passengers’ seat belt warning buzzer:
The rear passengers’ seat belt warning bu zzer sounds to alert the rear passengers
that his or her seat belt is not fastened. The buzzer so unds for 6 seconds after the
vehicle reaches a speed of 20 km/h (12 mph). Then, if the seat belt is still unfastened,
the buzzer will sound in a different tone for 24 more seconds.
■SRS warning light
This warning light system monitors the airbag sensor assembly, front impact sensors, side
impact sensors (front door), side impact se nsors (rear), driver’s seat position sensor,
driver’s seat belt buckle sw itch, front passenger occupant classification system (ECU and
sensors), “AIR BAG ON” indicator light, “A IR BAG OFF” indicator light, front passen-
ger’s seat belt buckle switch, driver’s seat belt pretension er, front passenger’s seat belt
pretensioner and force limiter, airbags, in terconnecting wiring and power sources.
(  P. 36)
■Front passenger detection sensor, seat belt reminder and warning buzzer
●If luggage is placed on the front passenger seat, the front passenger detection sensor
may cause the warning light to flash and the warning buzzer to sound even if a passen-
ger is not sittin g in the seat.
●If a cushion is placed on the seat, the sens or may not detect a passenger, and the warn-
ing light may not operate properly.
■Electric power steering system warning light (warning buzzer)
When the battery charge becomes insufficien t or the voltage temporarily drops, the
electric power steering system warning li ght may come on and the warning buzzer may
sound.
Master warning light A buzzer sounds and the warning light comes on and flashes to
indicate that the master warnin g system has detected a malfunc-
tion.
 P. 661
Warning lightWarning light/Details/Actions

6588-2. Steps to take in an emergency
RX350/RX350L_U
■If the malfunction indicator lamp comes on while driving
First check the following:
●Is the fuel tank empty?
If it is, fill the fuel tank immediately.
●Is the fuel tank cap loose?
If it is, tighten it securely.
The light will go off after several driving trips.
If the light does not go off even after severa l trips, contact your Lexus dealer as soon as
possible.
■When the tire pressure warning light comes on
Inspect the tires to check if a tire is punctured.
If a tire is punctured: P. 666
If none of the tires are punctured:
Turn the engine switch off then turn it to IGNITION ON mode. Check if the tire pressure
warning light comes on or blinks.
If the tire pressure warning light comes on
After the temperature of the tires has lowere d sufficiently, check the inflation pressure
of each tire and adjust th em to the specified level.
If the warning light does not turn off even after several minutes have elapsed, check
that the inflation pressure of each tire is at the specified level and perform initialization.
(  P. 606)
If the warning light does not turn off severa l minutes after the initialization has been per-
formed, have the vehicle inspected by your Lexus dealer immediately.
If the tire pressure wa rning light blinks for 1 minute then stays on
There may be a malfunction in the tire pressure warning system. Have the vehicle
inspected by your Lexus dealer immediately.
■The tire pressure warning light ma y come on due to natural causes
The tire pressure warning light may come on due to natural causes such as natural air
leaks and tire inflation pressure changes caus ed by temperature. In this case, adjusting
the tire inflation pressure will turn off the warning light (after a few minutes).
■When a tire is replaced with a spare tire
The compact spare tire is not equipped with a tire pressure warning valve and transmit-
ter. If a tire goes flat, the tire pressure warning light will not turn off even though the flat
tire has been replaced with the spare tire. Replace the spare tire with the repaired tire
and adjust the tire inflation pressure. The tire pressure warnin g light will go off after a few
minutes.
■Conditions that the tire pressure wa rning system may not function properly
 P. 609
■Warning buzzer
In some cases, the buzzer ma y not be heard due to being in a noisy location or audio
sound.
■Customization
Some functions can be customized. ( P. 722)
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6708-2. Steps to take in an emergency
RX350/RX350L_U
Secure the deck board using the hook. (P. 540)
Disengage the hook and take out
the jack.
RX350: Remove the wheel nut wrench
and then the jack
RX350L: Remove the jack handle and
then the jack
RX350
Secure the deck board using the hook. ( P. 540)
Loosen the center fastener that
secures the spare tire.
RX350L
Remove the deck board.
Remove the cover.
Taking out the jack
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Taking out the spare tire
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6808-2. Steps to take in an emergency
RX350/RX350L_U
WARNING
■When using the compact spare tire
●Remember that the compact spare tire provided is specifically designed for use with
your vehicle. Do not use your comp act spare tire on another vehicle.
●Do not use more than one compact spare tire simultaneously.
●Replace the compact spare tire with a standard tire as soon as possible.
●Avoid sudden acceleration, abrupt steering, sudden braking and shifting operations
that cause sudden engine braking.
■When the compact spare tire is attached
The vehicle speed may not be correctly detected, and the following systems may not
operate correctly:
Also, not only can the following system not be utilized fully, but it may even negatively
affect the drive-train components:
• AWD system (AWD models)
■Speed limit when using the compact spare tire
Do not drive at speeds in excess of 50 mph (80 km/h) when a compact spare tire is
installed on the vehicle.
The compact spare tire is not designed for driving at high speeds. Failure to observe
this precaution may lead to an accident causing death or serious injury.
■After using the tools and jack
Before driving, make sure all the tools and jack are securely in place in their storage
location to reduce the possibilit y of personal injury during a collision or sudden brak-
ing.
• ABS & Brake assist
•VSC
•TRAC
• Trailer Sway Control
•EPS
• VDIM (if equipped)
• Adaptive Variable Suspension System (if equipped)
• Dynamic radar cruise control with full- speed range
• PCS (Pre-Collision System)
• LKA (Lane-keeping Assist)
• Automatic High Beam • AFS (Adaptive Front-lighting System)
(if equipped)
• Tire pressure warning system
• Intuitive parking assist (if equipped)
• Intelligent Clearance Sonar (ICS) (if equipped)
• Lexus parking assist monitor (if equipped)
• Panoramic view monitor (if equipped)
• BSM (Blind Spot Monitor) (if
equipped)
• Navigation system (if equipped)

6818-2. Steps to take in an emergency
8
When trouble arises
RX350/RX350L_U
NOTICE
■Be careful when driving over bumps with the compact spare tire installed on the vehi-
cle
When driving with the compact spare tire installed, the vehicle height will be different
than when driving with standard tires. Be careful when driving over uneven road sur-
faces, etc.
■Driving with tire chains and the compact spare tire
Do not fit tire chains to the compact spare tire.
Tire chains may damage the vehicle body and adversely affect driving performance.
■When replacing the tires
When removing or fitting the wheels, tires or the tire pressure warning valve and trans-
mitter, contact your Lexus dealer as the tire pressure warning valve and transmitter
may be damaged if not handled correctly.
■When stowing the flat tire (RX350L)
●Ensure that there is no object caught between the tire and the vehicle underbody.
●Securely tighten the spare tire clamp bolt to hold the spare wheel carrier by the hook.
●Stow the flat tire in the spare tire location. Failure to do so may cause damage to the
spare tire carrier. Proper storage reduces the possibilit y of injury in a collision or
during sudden braking.
●Have the flat tire repaired and the spare tire replaced with it as soon as possible.
■Proper storage of the spare tire (RX350L)
●If the spare tire clamp bolt is turned withou t a tire on the hoist assembly, the wire cable
may not be able to be lowered. If the wire cable cannot be lowered, contact your
Lexus dealer.
●If the hoist assembly is slanted when stowing a
tire, the hoist assembly may become stuck in
the wheel opening and the tire may not be
raised properly, causing damage to the wheel
or the wire cable.

6898-2. Steps to take in an emergency
8
When trouble arises
RX350/RX350L_U
■Starting the engine when the battery is discharged
The engine cannot be started by push-starting.
■To prevent battery discharge
●Turn off the headlights and the audio system while the engine is off.
●Turn off any unnecessary electrical components when the vehicle is running at a low
speed for an extended period, such as in heavy traffic.
■When removing the battery terminals
When the battery terminals are removed, the information stored in the ECU is cleared.
Before removing the battery termin als, contact your Lexus dealer.
■Charging the battery
The electricity stored in the battery will disc harge gradually even when the vehicle is not
in use, due to natural discharge and the draini ng effects of certain electrical appliances. If
the vehicle is left for a long time, the battery may discharge, and the engine may be
unable to start. (The battery recharges automatically during driving.)
■When the battery is removed or discharged
●In some cases, it may not be possible to un lock the doors using the smart access system
with push-button start when the battery is discharged. Use the wireless remote control
or the mechanical key to lock or unlock the doors.
●The engine may not start on the first attempt after the battery has recharged but will
start normally after the second attempt. This is not a malfunction.
●The engine switch mode is memorized by the vehicle. When the battery is recon-
nected, the system will return to the mode it was in before the battery was discharged.
Before disconnecting the battery, turn the engine switch off.
If you are unsure what mode the engine switch was in before the battery discharged, be
especially careful when reconnecting the battery.
●The power back door must be initialized. ( P. 138)
■When replacing the battery
●Use a battery with the same case size as the previous battery and an equivalent 20
hour rate capacity (20HR) or greater.
• If the sizes differ, the battery cannot be properly secured.
• If the 20 hour rate capacity is low, even if the time period where the vehicle is not used is a short time, the battery may discharge and the engine may not be able to
start.
●For details, consult your Lexus dealer.