2021 LEXUS RX450h Owners Manual

4497-2. Steps to take in an emergency
7
When trouble arises
When the smart access system with
push-button start is deactivated in custom-
ization setting, the powe r switch will turn to
ACCESSORY mode.
3 Firmly depress the brake pedal and
check that is shown on the
multi-information display.
4 Press the power switch shortly and
firmly.
In the event that the hybrid system still
cannot be started, contact your Lexus
dealer.
■Stopping the hybrid system
Shift the shift lever to P, set the parking
brake, and press the power switch as you
normally do when stopping the hybrid sys-
tem.
■Replacing the key battery
As the above procedure is a temporary
measure, it is recomme nded that the elec-
tronic key battery be replaced immediately
when the battery is depleted. ( P.393)
■Alarm (For Canada)
Using the mechanical key to lock the doors
will not set the alarm system.
If a door is unlocked using the mechanical
key when the alarm system is set, the alarm
may be triggered. ( P.75)
■Changing power switch modes
Release the brake pedal and press the
power switch in step 3 above. The hybrid
system does not start and modes will be
changed each time the switch is pressed.
(  P.187)
If the 12-volt battery is dis-
charged
The following procedures may be
used to start the hybrid system if the
vehicle’s 12-volt battery is dis-
charged.
You can also call your Lexus dealer
or a qualified repair shop.

4507-2. Steps to take in an emergency
If you have a set of jumper (or booster)
cables and a second vehicle with a
12-volt battery, you can jump start your
vehicle by following the steps below.
1Confirm that the electronic key is
being carried.
When connecting the jumper (or booster)
cables, depending on the situation, the
alarm may activate and doors locked.
( P.76)
2 Open the hood ( P.369) and fuse
box cover. 3
Open the exclusive jump starting
terminal cover.
4 Remove the engine cover.
5 Connect a positive jumper cable clamp to on your vehicle and connect the
clamp on the other end of the positive cab le to on the second vehicle. Then,
Restarting the hybrid system
A
B

4517-2. Steps to take in an emergency
7
When trouble arises
connect a negative cable clamp to on the second vehicle and connect the
clamp at the other end of the negative cable to .
Exclusive jump starting terminal (your vehicle)
Positive (+) battery terminal (second vehicle)
Negative (-) battery terminal (second vehicle)
Solid, stationary, unpainted metallic point away from the exclusive jump starting
terminal and any mo ving parts as shown in the illustration
6 Start the engine of the second vehi-
cle. Increase the engine speed
slightly and maintain at that level for
approximately 5 minutes to
recharge the 12-volt battery of your
vehicle.
7 Open and close any of the doors of
your vehicle with the power switch
off.
8 Maintain the engine speed of the
second vehicle and start the hybrid
system of your vehicle by turning
the power switch to ON mode.
9 Make sure the “READY” indicator
comes on. If the indicator light does
not come on, contact your Lexus
dealer. 10
Once the hybrid system has
started, remove the jumper cables
in the exact reverse order from
which they were connected.
11 Close the exclusive jump starting
terminal cover, and reinstall the fuse
box cover to its original position.
Once the hybrid system starts, have
the vehicle inspected at your Lexus
dealer as soon as possible.
■Starting the hybrid system when the
12-volt battery is discharged
The hybrid system cannot be started by
push-starting.
■To prevent 12-volt battery discharge
●Turn off the headlights and the audio sys-
tem while the hybrid system is off.
●Turn off any unnecessary electrical com-
C
D
A
B
C
D

4527-2. Steps to take in an emergency
ponents when the vehicle is running at a
low speed for an extended period, such
as in heavy traffic.
■When removing the 12-volt battery ter-
minals
When the 12-volt battery terminals are
removed, the information stored in the
ECU is cleared. Before removing the
12-volt battery terminals, contact your
Lexus dealer.
■Charging the 12-volt battery
The electricity stored in the 12-volt battery
will discharge gradually even when the
vehicle is not in use, due to natural dis-
charge and the draining effects of certain
electrical appliances. If the vehicle is left for
a long time, the 12-volt battery may dis-
charge, and the hybrid system may be
unable to start. (The 12-volt battery
recharges automatically while the hybrid
system is operating.)
■When the 12-volt battery is removed or
discharged
●In some cases, it may not be possible to
unlock the doors using the smart access
system with push-button start when the
12-volt battery is discharged. Use the
wireless remote control or the mechani-
cal key to lock or unlock the doors.
●The hybrid system may not start on the
first attempt after the 12-volt battery has
recharged but will start normally after the
second attempt. This is not a malfunction.
●The power switch mode is memorized by
the vehicle. When the 12-volt battery is
reconnected, the system will return to the
mode it was in before the 12-volt battery
was discharged. Before disconnecting
the 12-volt battery, turn the power switch
off.
If you are unsure what mode the power
switch was in before the 12-volt battery
discharged, be especially careful when
reconnecting the 12-volt battery.
●The power back door mu st be initialized.
(  P.119)
■When replacing the 12-volt battery
●RX450h: Use a Central Degassing type
12-volt battery (European Regulations). RX450hL: Use a 12-volt battery
designed for this vehicle.
●RX450h: Use a 12-volt battery that the
case size is same
as the previous one
(LN2), 20 hour rate capacity (20HR) is
equivalent (60Ah) or greater, and per-
formance rating (CCA) is equivalent
(460A) or greater.
• If the sizes differ, the 12-volt battery can- not 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 12-volt battery
may discharge and the hybrid system
may not be able to start.
●Use a 12-volt battery with a handle. If a
12-volt battery without a handle is used,
removal is more difficult.
●After replacing, firm ly attach the follow-
ing items to the exhaust hole of the
12-volt battery.
• Use the exhaust hose that was attached to the 12-volt battery before replacing
and confirm that it is firmly connected to
the hole section of the vehicle.
• Use the exhaust hole plug included with the 12-volt battery re placed or the one
installed on the 12-volt battery prior to
the replacement. (Depending on the
12-volt battery to be replaced, the
exhaust hole may be plugged.)
RX450h
Exhaust hole plug
Exhaust hole
A
B

4537-2. Steps to take in an emergency
7
When trouble arises
Exhaust hose
Hole section of the vehicle
RX450hLExhaust hole
Exhaust hose
Hole section of the vehicle
●For details, consult your Lexus dealer.
WARNING
■When removing the 12-volt battery
terminals
Always remove the negative (-) terminal
first. If the positive (+) terminal contacts
any metal in the surrounding area when
the positive (+) terminal is removed, a
spark may occur, leading to a fire in addi-
tion to electrical shocks and death or
serious injury.
■Avoiding 12-volt battery fires or
explosions
Observe the following precautions to
prevent accidentally igniting the flamma-
ble gas that may be emitted from the
12-volt battery:
●Make sure each jumper cable is con-
nected to the correct terminal and that
it is not unintentiona lly in contact with
any other than the intended terminal.
●Do not allow the other end of the
jumper cable connected to the “+” ter-
minal to come into contact with any
other parts or metal surfaces in the
area, such as brackets or unpainted
metal.
C
D
A
B
C
●Do not allow the + and - clamps of the
jumper cables to come into contact
with each other.
●Do not smoke, use matches, cigarette
lighters or allow open flame near the
12-volt battery.
■12-volt battery precautions
The 12-volt battery contains poisonous
and corrosive acidic electrolyte, while
related parts contain lead and lead com-
pounds. Observe the following precau-
tions when handling the 12-volt battery:
●When working with the 12-volt battery,
always wear safety glasses and take
care not to allow any battery fluids
(acid) to come into contact with skin,
clothing or the vehicle body.
●Do not lean over the 12-volt battery.
●In the event that battery fluid comes
into contact with the skin or eyes,
immediately wash the affected area
with water and seek medical attention.
Place a wet sponge or cloth over the
affected area until medical attention
can be received.
●Always wash your ha nds after handling
the 12-volt battery support, terminals,
and other battery-related parts.
●Do not allow children near the 12-volt
battery.
■After recharging the 12-volt battery
Have the 12-volt battery inspected at
your Lexus dealer as soon as possible.
If the 12-volt battery is deteriorating, con-
tinued use may cause the 12-volt battery
to emit a malodorous gas, which may be
detrimental to the health of passengers.
■When replacing the 12-volt battery
●When the vent plug and indicator are
close to the hold down clamp, the bat-
tery fluid (sulfuric acid) may leak.
●For information regarding 12-volt bat-
tery replacement, contact your Lexus
dealer.

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

4557-2. Steps to take in an emergency
7
When trouble arises
and radiator core (radiator) for any
leaks.
Radiator
Cooling fans
If a large amount of coolant leaks, immedi-
ately contact your Lexus dealer.
4The coolant level is satisfactory if it
is between the “FULL” and “LOW”
lines on the reservoir.
Reservoir
“FULL” line
“LOW” line
Radiator cap
5 Add coolant if necessary.
Water can be used in an emergency if coolant is unavailable.
6
Start the hybrid system and turn the
air conditioning system on to check
that the radiator cooling fans oper-
ate and to check for coolant leaks
from the radiator or hoses.
The fans operate when the air conditioning
system is turned on immediately after a
cold start. Confirm that the fans are oper-
ating by checking the fan sound and air
flow. If it is difficult to check these, turn the
air conditioning system on and off repeat-
edly.
(The fans may not oper ate in freezing tem-
peratures.)
7 If the fans are not operating:
Stop the hybrid system immediately
and contact your Lexus dealer.
If the fans are operating:
Have the vehicle inspected at the
nearest Lexus dealer.
8 Check if “Engine Coolant Temp
High Stop in a Safe Place See
Owner's Manual” is shown on the
multi-information display.
If the message does not disappear:
Stop the hybrid system and contact your
Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the nearest
A
B
A
B
C
D

4567-2. Steps to take in an emergency
Lexus dealer.
If “Hybrid System Overheated Out-
put power reduced” is shown on the
multi-information display
1 Stop the vehicle in a safe place.
2 Stop the hybrid system and care-
fully lift the hood.
3 After the hybrid system has cooled
down, inspect the hoses and radia-
tor core (radiator) for any leaks.
Radiator
Cooling fans
If a large amount of coolant leaks, immedi-
ately contact your Lexus dealer.
4The coolant level is satisfactory if it
is between the “FULL” and “LOW”
lines on the reservoir.
Reservoir
“FULL” line
“LOW” line 5
Add coolant if necessary.
Water can be used in an emergency if
coolant is unavailable.
6Start the hybrid system and check if
“Hybrid System Overheated Out-
put power reduced” is shown on
the multi-information display.
If the message does not disappear:
Stop the hybrid system and contact
your Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the
nearest Lexus dealer.
A
B
A
B
C
WARNING
■When inspecting under the hood of
your vehicle
Observe the following precautions.
Failure to do so may result in serious
injury such as burns.
●If steam is seen coming from under the
hood, do not open the hood until the
steam has subsided. The engine com-
partment may be very hot.