Page 561 of 660

5617-2. Steps to take in an emergency
7
When trouble arises
RX450h_U_OM0E013U One of the following may be the cause of the problem: ●
The electronic key may not be functioning properly.
( P. 5 6 4 )●
There may not be sufficient fuel in the vehicle’s tank.
Refuel the vehicle. ●
There may be a malfunction in the immobilizer system. ( P. 8 5 )●
There may be a malfunction in the steering lock system. ●
The hybrid system may be malfunctioni ng due to an electrical problem such
as electronic key battery depletion or a blown fuse. However, depending on
the type of malfunction, an interim meas ure is available to start the hybrid sys-
tem. ( P. 5 6 2 )
One of the following may be the cause of the problem: ●
The 12-volt battery may be discharged. ( P. 5 6 8 )●
The 12-volt battery terminal connections may be loose or corroded.
( P. 4 8 3 )If the hybrid system will not start Reasons for the hybrid system not starting vary depending on the situation.
Check the following and perform the appropriate procedure:
The hybrid system will not start ev en though the correct starting proce-
dure is being followed. ( P. 2 3 2 )
The interior lights and headlights are dim, or the horn does not sound or
sounds at a low volume.
Page 562 of 660

562 7-2. Steps to take in an emergency
RX450h_U_OM0E013U One of the following may be the cause of the problem: ●
The 12-volt battery may be discharged. ( P. 5 6 8 )●
One or both of the 12-volt battery terminals may be disconnected. ( P. 4 8 3 )Contact your Lexus dealer if the problem cannot be repaired, or if repair procedures
are unknown.
When the hybrid system does not start, the following steps can be used as an
interim measure to start the hybrid system if the power switch is functioning nor-
mally.
Do not use this starting procedur e except in cases of emergency.
Turn the power switch to ON mode and check that the parking brake is set.
( P. 2 3 3 , 2 4 5 )
Shift the shift lever to P.
Turn the power switch to ACCESSORY mode.
Press and hold the power switch for ab out 15 seconds while depressing the
brake pedal firmly.
Even if the hybrid system can be starte d using the above steps, the system may
be malfunctioning. Have the vehicle inspected by your Lexus dealer.The interior lights and headlights do not turn on, or the horn does not
sound.
Emergency start function 1
2
3
4
Page 564 of 660
564 7-2. Steps to take in an emergency
RX450h_U_OM0E013U ■
Unlocking the door
Use the mechanical key ( P. 133) in order to perform the following opera-
tions:
Insert the mechanical key while
pulling on the driver’s door han-
dle.
Unlocking the door. Turning the key rearward unlocks the
driver’s door. Turning the key again
unlocks the other doors.
Remove the key, return the handle, and then pull the handle again.If the electronic key do es not operate properlyIf communication between the electron ic key and vehicle is interrupted
( P. 160) or the electronic key ca nnot be used because the battery is
depleted, the smart access system with push-button start and wireless
remote control cannot be used. In such cases, the doors can be opened and
the hybrid system can be started by following the procedure below.
Locking and unlocking the doors 1
2
3
Page 567 of 660

5677-2. Steps to take in an emergency
7
When trouble arises
RX450h_U_OM0E013U ■
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 system. ■
Replacing the key battery
As the above procedure is a temporary measure, it is recommended that the electronic
key battery be replaced immediately when the battery is depleted. ( P. 5 0 6 )■
Changing power switch modes
Release the brake pedal and press the power switch in step above.
The hybrid system does not start and mode s will be changed each time the switch is
pressed. ( P. 2 3 3 )■
When the electronic key does not work properly ●
Make sure that the smart access system wi th push-button start has not been deacti-
vated in the custom ization setting. If it is off, turn the function on.
(Customizable features P. 6 1 0 )●
Check if battery-saving mo de is set. If it is se t, cancel the function. ( P. 1 6 0 )
WA R N I N G ■
When using the mechanical key and operating the power windows or the moon roof
or panoramic moon roof
Operate the power window or the moon roof or panoramic moon roof after checking
to make sure that there is no possibility of any passenger ha ving any of their body parts
caught in the window or the moon roof or panoramic moon roof.
Also, do not allow children to operate the mech anical key. It is possible for children and
other passengers to get caught in the powe r window or the moon roof or panoramic
moon roof. 3
Page 568 of 660
568 7-2. Steps to take in an emergency
RX450h_U_OM0E013U 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.
Confirm that the electronic key is
being carried. When connecting the jumper (or
booster) cables, depending on the situa-
tion, the alarm may activate and doors
locked. (
P. 8 8 )
Open the hood ( P. 4 7 3 ) a n d f u s e
box cover.
Open the exclusive jump starting
terminal cover.If the 12-volt battery is discharged The following procedures may be used to start the hybrid system if the vehi-
cle’s 12-volt battery is discharged.
You can also call your Lexus dealer or a qualified repair shop. 1
2
3
Page 569 of 660
5697-2. Steps to take in an emergency
7
When trouble arises
RX450h_U_OM0E013U Remove the engine cover.
Connect the jumper cables according to the following procedure:
Connect a positive jumper cable clamp to the exclusive jump starting ter-
minal on your vehicle.
Connect the clamp on the other end of the positive cable to the positive (+)
battery terminal on the second vehicle.
Connect a negative cable clamp to the negative (-) battery terminal on the
second vehicle.
Connect the clamp at the other end of the negative cable to a solid, station-
ary, unpainted metallic point away from the exclusive jump starting terminal
and any moving parts, as shown in the illustration. 4
5
1
2
3
4
Page 570 of 660

570 7-2. Steps to take in an emergency
RX450h_U_OM0E013U Start the engine of the second vehicle. Increase the engine speed slightly and
maintain at that level for approximately 5 minutes to recharge the 12-volt bat-
tery of your vehicle.
Open and close any of the doors of your vehicle with the power switch off.
Maintain the engine speed of the second vehicle and start the hybrid system
of your vehicle by turning the power switch to ON mode.
Make sure the “READY” indicator comes on. If the indicator light does not
come on, contact your Lexus dealer.
Once the hybrid system has started, remove the jumper cables in the exact
reverse order from which they were connected.
Close the exclusive jump starting terminal cover, and reinstall the fuse box
cover to its original position.
Once the hybrid system starts, have th e 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 system while the hybrid system 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. ■
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 discharge and th e draining effects of certain electrical appli-
ances. If the vehicle is left for a long time, the 12-volt battery may discharge, 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 mechanical 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 dis-
charged, be especially careful when reconnecting the 12-volt battery. ●
The power back door must be initialized. ( P. 1 5 0 )6
7
8
9
10
11
Page 571 of 660

5717-2. Steps to take in an emergency
7
When trouble arises
RX450h_U_OM0E013U ■
When exchanging the 12-volt battery ●
Use a Central Degassing type 12-volt battery (European Regulations). Also, use 12-volt
batteries with case si zes similar to one prior the exchange and an equivalent 20 hour
rate capacity (20HR) or greater.
• If the sizes differ, the 12-volt 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 12-volt battery may discharge and hybrid system may not be
able to start. ●
After exchanging, firmly attach the following items to the exhaust hole of the 12-volt
battery.
For details, consult your Lexus dealer. • Use the exhaust hose that was attached to
the 12-volt battery before exchanging 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 exchanged or the one
installed on the battery prior to the
exchange. (Depending on the 12-volt bat-
tery to be exchanged, the exhaust hole may
be plugged.)
Exhaust hole plug
Exhaust hole
Exhaust hose
Hole section of the vehicle 1
2
3
4