Page 695 of 792
6958-2. Steps to take in an emergency
8
When trouble arises
RX450h_RX450hL _U_OM48F85UIf 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, depe nding on the situa-
tion, the alarm may activate and doors
locked. (
→ P. 87)
Open the hood ( → P. 595) and fuse
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 deal er or a qualified repair shop.1
2
3
Page 696 of 792
696 8-2. Steps to take in an emergency
RX450h_RX450hL _U_OM48F85URemove the engine cover.
Connect the jumper cables accordin g 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 th e negative cable to a solid, station-
ary, unpainted meta llic point away from the excl usive jump starting terminal
and any moving parts, as shown in the illustration. 4
5
1
2
3
4
Page 697 of 792

6978-2. Steps to take in an emergency
8
When trouble arises
RX450h_RX450hL _U_OM48F85UStart the engine of the second vehicle. Increase the engine speed slightly and
maintain at that level for approximatel y 5 minutes to recharge the 12-volt bat-
tery of your vehicle.
Open and close any of the doors of yo ur vehicle with the power switch off.
Maintain the engine speed of the seco nd vehicle and start the hybrid system
of your vehicle by turning th e 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 termin al 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 componen ts 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.6
7
8
9
10
11
Page 700 of 792

700 8-2. Steps to take in an emergency
RX450h_RX450hL _U_OM48F85UWARNING ■
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 cab le 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 light ers or allow open flame near the 12-volt
battery. ■
12-volt battery precautions
The 12-volt battery contains poisonous and co rrosive acidic electr olyte, 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, always 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 yo ur 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 replacing the 12-volt battery ●
When the vent plug and indicator are close to the hold down clamp, the battery fluid
(sulfuric acid) may leak. ●
For information regarding 12-volt battery replacement, contact your Lexus dealer.●
Make sure to replace the 12-volt battery with one designed for this vehicle. Other-
wise, 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 (hydro-
gen) may leak into the vehicle interior, an d there is the possible danger of the gas
igniting and exploding.
Page 701 of 792
7018-2. Steps to take in an emergency
8
When trouble arises
RX450h_RX450hL _U_OM48F85UNOTICE ■
When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in the
cooling fans or belt. ■
To prevent damaging the vehicle
The exclusive jump starting te rminal is to be used when charging the 12-volt battery
from another vehicle in an emergency. It cannot be used to jump start another vehicle.