Page 593 of 681
5938-2. Steps to take in an emergency
8
When trouble arises
NX300h_U_OM78007U ■
Locking the door
Move the inside lock button to the
lock position.
Close the door. ■
Key linked functions
Ensure that the shift lever is in P and depress the brake pedal.
Touch the Lexus emblem side of the
electronic key to the power switch. When the electronic key is detected, a
buzzer sounds and the power switch will
turn to ON mode.
When the smart access system with
push-button start is deactivated in cus-
tomization setting, the power switch will
turn to ACCESSORY mode.
Firmly depress the brake pedal and
check that message shown on the
multi-information display. 1
Closes the windows and moon roof
*
(turn and hold)
Opens the windows and moon roof
*
(turn and hold)
* : These settings must be customized at your
Lexus dealer or repairer, or another duly
qualified and equipped professional.
Starting the hybrid system 2 1
2
1
2
3
Page 594 of 681

594 8-2. Steps to take in an emergency
NX300h_U_OM78007U Press the power switch.
In the event that the hybrid system st ill cannot be operated, contact your Lexus
dealer. ■
Stopping the hybrid system
Set the parking brake, shift the shift lever to P 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 immediatel y when the battery is depleted. ( P. 5 3 2 )■
Alarm (if equipped)
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 al arm system is set, the alarm may be trig-
gered. ■
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. 202)■
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 3 5 )●
Check if battery-saving mo de is set. If it is se t, cancel the function. ( P. 1 4 2 )
WA R N I N G ■
When using the mechanical key and operating the power windows or moon roof
Operate the power window or moon roof afte r checking to make sure that there is no
possibility of any passenger having any of their body parts caught in the window or
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 power window or moon roof. 4
3
Page 595 of 681
595
8
When trouble arises 8-2. Steps to take in an emergency
NX300h_U_OM78007UIf the 12-volt battery is discharged 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.
Open the hood ( P. 5 0 0 ) a n d f u s e
box cover.
Open the exclusive jump starting
terminal cover.
Remove the engine cover.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 596 of 681
596 8-2. Steps to take in an emergency
NX300h_U_OM78007U 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
1
2
3
4
Page 597 of 681

5978-2. Steps to take in an emergency
8
When trouble arises
NX300h_U_OM78007U 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 the 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 3 4 )●
Make sure that the key is not inside the vehicle when recharging or replacing the
12-volt battery. The key may be locked in the vehicle if the alarm is activated. ( P. 88)5
6
7
8
9
10
Page 598 of 681

598 8-2. Steps to take in an emergency
NX300h_U_OM78007U ■
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 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 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.)
WA R N I N G ■
Avoiding 12-volt battery fires or explosions
Observe the following precautions to preven t accidentally igniting the flammable gas
that may be emitted from the 12-volt battery: ●
Make sure each jumper cable is connected to the correct terminal and that it is not
unintentionally in contact with any other than the intended terminal.●
Do not allow the other end of the jumper cable connected to the “+” terminal to come
into contact with any other parts or metal surfaces in the area, such as brackets or
unpainted metal. ●
Do not allow the + and - clamps of the jump er cables to come in to contact with each
other. ●
Do not smoke, use matches, cigarette lighters or allow open flame near the 12-volt
battery. Exhaust hole
Exhaust
hole plug
Exhaust hoseHole section
of the vehicle
Exhaust hole
Page 599 of 681

5998-2. Steps to take in an emergency
8
When trouble arises
NX300h_U_OM78007U WA R N I N G ■
12-volt battery precautions
The 12-volt battery contains poisonous and corrosive acidic electrolyte, while related
parts contain lead and lead compounds. Ob serve the following precautions when han-
dling the 12-volt battery: ●
When working with the 12-volt battery, alwa ys wear safety glasses and take care not
to allow any battery fluids (acid) to come in to 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 hands 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, continued use may cause the 12-volt battery to
emit a malodorous gas, which may be de trimental to the health of passengers.■
When exchanging the 12-volt battery
After exchanging, securely attach the exha ust hose and exhaust hole plug to the
exhaust hole of the exchanged 12-volt battery. If not properly installed, gases (hydro-
gen) may leak into the vehicle interior, and th ere is the possible danger of the gas ignit-
ing and exploding.
NOTICE ■
When handling jumper cables
When connecting the jumper cables, ensure th at they do not become entangled 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 battery
from another vehicle in an emergency. It ca nnot be used to jump start another vehicle.
Page 600 of 681

600 8-2. Steps to take in an emergency
NX300h_U_OM78007UIf your vehicle overheats ■
“Engine Coolant Temp High” is shown on the multi-information display
Stop the vehicle in a safe place and tu rn off the air conditioning system, and
then stop the hybrid system.
If you see steam: Carefully lift the hood after the steam subsides.
If you do not see steam: Carefully lift the hood.
After the hybrid system has cooled down sufficiently, inspect the hoses and
radiator core (radiator) for any leaks.
Radiator
Cooling fans If a large amount of coolant leaks,
immediately contact your Lexus
dealer.The following may indicate that your vehicle is overheating. ●
The needle of the engine coolant temperature gauge ( P. 97) enters the
red zone, or a loss of hybrid system po wer is experienced. (For example, the
vehicle speed does not increase.) ●
“Engine Coolant Temp High” or “Hybrid System Overheated” is shown on
the multi-information display. ●
Steam comes out from under the hood.
Correction procedures 1
2
3
1
2