Page 769 of 860
7697-2. Steps to take in an emergency
GS450h_U (OM30D01U)
7
When trouble arises
■Stopping the hybrid system
Shift the shift lever to P and press the power switch as you normally do when stop-
ping the hybrid system.
■Replacing the key battery
As the above procedure is a temporary measure, it is recommended that the elec-
tronic key battery be replaced immediately when the battery is depleted. ( P. 668)
■Changing power switch modes
Release the brake pedal and press the power switch in step above.
The hybrid system does not start and modes will be changed each time the switch is
pressed.( P. 1 9 0 )
■When the electronic key does not work properly
●Make sure that the smart access system with push-button start has not been deac-
tivated in the customization setting. If it is off, turn the function on.
(Customizable features P. 8 0 7 )
●Check if battery-saving mode is set. If it is set, cancel the function. ( P. 1 2 7 )
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Page 770 of 860
770
GS450h_U (OM30D01U)
7-2. Steps to take in an emergency
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 can-
not be used, use the mechanical key to
open the trunk. ( P. 76 7 )
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
The following procedures may be used to start the hybrid system if the
12-volt battery is discharged.
You can also call your Lexus dealer or a qualified repair shop.
1
2
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Page 771 of 860

7717-2. Steps to take in an emergency
GS450h_U (OM30D01U)
7
When trouble arises
Start the engine of the second vehicle. Increase the engine speed
slightly and maintain at that le vel for approximately 5 minutes to
recharge the 12-volt battery of your vehicle.
Open and close any of th e doors of your vehicle with the power switch
off.
Maintain the engine speed of the se cond vehicle and start the hybrid
system of your vehicle by turning the power switch to ON mode.
Make sure the “READY” indicator co mes on. If the indicator does not
come on, contact your Lexus dealer.
Once the hybrid system has started, remove the jumper cables in the
exact reverse order from wh ich they were connected.
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 system while the hybrid system is off.
●Turn off any unnecessary electrical compon ents 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 elec-
trical 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.)
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Page 772 of 860

7727-2. Steps to take in an emergency
GS450h_U (OM30D01U)
■When recharging or replacing the 12-volt battery
●Make sure the key is not inside the vehicle when recharging or replacing the 12-volt
battery to prevent the doors from being locked with the key left inside the vehicle
when the alarm operates.
●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 wire-
less remote control or the mechanical key to lock or unlock the doors.
●The hybrid system may not start on the fir st 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.
CAUTION
■Avoiding 12-volt battery fires or explosions
Observe the following precautions to prev ent 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 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.
Page 773 of 860

7737-2. Steps to take in an emergency
GS450h_U (OM30D01U)
7
When trouble arises
CAUTION
■12-volt battery precautions
The 12-volt battery contains poisonous and corrosive acidic electrolyte, while
related parts contain lead and lead compounds. 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 12-volt battery fluids (aci d) to come into contact with skin, cloth-
ing or the vehicle body.
●Do not lean over the 12-volt battery.
●In the event that 12-volt 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 th e 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 detrimental to the health of passengers.
■When replacing the 12-volt battery
P. 6 5 0
Page 774 of 860

774
GS450h_U (OM30D01U)
7-2. Steps to take in an emergency
If your vehicle overheats
●The needle of the engine coolant temperature gauge enters the red
zone:
The engine may be overheating.
●“Hybrid System Overheat” is shown on the multi-information display:
The power control unit may be overheating.
■If the needle of the engine coolant temperature gauge enters the red
zone
Stop the vehicle in a safe place an d turn off the air conditioning sys-
tem.
Check to see if steam is coming out from the engine area.
If you see steam:
Stop the hybrid system. Carefull y lift the hood after the steam sub-
sides and then restart the hybrid system.
If you do not see steam:
Leave the hybrid system operating and carefully lift the hood.
Check to see if the cooling fans are operating.
If the fans are operating:
Wait until the engine coolant temperature ga uge begins to fall and
then stop the hybrid system.
If the fans are not operating:
Stop the hybrid system immediately and call your Lexus dealer.
The following may indicate that your vehicle is overheating:
Correction procedures
1
2
3
Page 775 of 860

7757-2. Steps to take in an emergency
GS450h_U (OM30D01U)
7
When trouble arises
After the hybrid system has
cooled down sufficiently,
check the engine coolant level
and inspect the cooling sys-
tem for leaks.
If the engine compartment cover
needs to be removed: P. 6 3 8
Add engine coolant if neces-
sary.
Water can be used in an emer-
gency if engine coolant is unavail-
able. ( P. 7 8 7 )
Have the vehicle inspected at the nearest Lexus dealer as soon as pos-
sible.
■If “Hybrid System Overheat” is shown on the multi-information dis-
play
Stop the vehicle in a safe place an d turn off the air conditioning sys-
tem.
Leave the hybrid system operating and carefully lift the hood.
Check if the cooling fans are operating.
If the fans are operating:
Wait until the “Hybrid System Overheat” message disappears and
then stop the hybrid system.
If the message does not disapp ear, call your Lexus dealer.
If the fans are not operating:
Stop the hybrid system immediately and call your Lexus dealer.
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Page 776 of 860
7767-2. Steps to take in an emergency
GS450h_U (OM30D01U)After the hybrid system has
cooled down, check the power
control unit coolant level and
inspect the cooling system for
leaks.
If the engine compartment cover
needs to be removed:
P. 6 3 8
Add power control unit cool-
ant if necessary.
Water can be used in an emer-
gency if power control unit coolant
is unavailable. ( P. 7 8 7 )
Have the vehicle inspected at the nearest Lexus dealer as soon as pos-
sible.
■Overheating
If you observe the following, your vehicle may be overheating:
●The engine coolant temperature gauge enters the red zone or a loss of power is
experienced.
●“Hybrid System Overheat” is shown on the multi-information display.
●Steam comes out from under the hood.
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