Page 940 of 1014

9137-2. Steps to take in an emergency
7
When trouble arises
GS450h_300h_OM_OM30D53E_(EE)
If 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 trunk lid and remove
the 12-volt battery cover.
In the event that the trunk opener
cannot be used, use the mechanical
key to open the trunk. (P. 910)
Connect the jumper cables according to the following procedure:
Positive (+) battery terminal on your vehicle
Positive (+) battery terminal on the second vehicle
Negative (-) battery terminal on the second vehicle
Negative (-) battery terminal on your vehicle
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 battery of your vehicle.
The following procedures may be used to start the hybrid system if
the 12-volt battery is discharged.
You can also call any authorized Lexus dealer or repairer, or
another duly qualified and equipped professional.
1
2
1
2
3
4
3
Page 941 of 1014

9147-2. Steps to take in an emergency
GS450h_300h_OM_OM30D53E_(EE)
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
does not come on, contact any authorized Lexus dealer or
repairer, or another duly qualified and equipped professional.
Once the hybrid system has started, remove the jumper cables in
the exact reverse order from which they were connected.
Once the hybrid system starts, have the vehicle inspected at any
authorized Lexus dealer or repairer, or another duly qualified and
equipped professional 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 appliances. 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.)
4
5
6
7
Page 942 of 1014

915
7 7-2. Steps to take in an emergency
When trouble arises
GS450h_300h_OM_OM30D53E_(EE)
When recharging or replacing the 12-volt battery
For vehicles with an alarm: 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. 99)
In some cases, it may not be possible to unlock the doors using the smart
entry & start system when the 12-volt battery is discharged. Use the wire-
less 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 bat-
tery 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 bat-
tery.
CAUTION
Avoiding 12-volt battery fires or explosions
Observe the following precautions to prevent 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 termi-
nal.
Do not allow the other end of the jumper cable connected to the “+” termi-
nal 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 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.