Page 609 of 676

6097-2. Steps to take in an emergency
7
When trouble arises
LS600h/LS600hL_EE(OM50G20E)
■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.
■When the 12-volt battery is removed or discharged
The hybrid system may not start. ( P. 504)
■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.)
■When recharging or replacing the 12-volt battery
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 wireless remote control
or the mechanical key to lock or unlock the doors.
■If the 12-volt battery is discharged
The information stored in the computer will be deleted.
If the 12-volt battery is discharged, have the vehicle inspected by your Lexus dealer.
Page 610 of 676

6107-2. Steps to take in an emergency
LS600h/LS600hL_EE(OM50G20E)
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 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.
■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 (acid) 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 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 any authorized Lexus dealer or repairer, or
another duly qualified and equipped professional 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. 505
Page 611 of 676

6117-2. Steps to take in an emergency
7
When trouble arises
LS600h/LS600hL_EE(OM50G20E)
●The needle of the engine coolant temperature gauge ( P. 115) enters
the red zone or a loss of hybrid system power is experienced. (For
example, the vehicle speed does not increase.)
●“Hybrid System Overheat” is shown on the multi-information display.
●Steam comes out from under the hood.
■If the needle of the engine cool ant temperature gauge enters the red
zone
Stop the vehicle in a safe place and turn off the air conditioning sys-
tem, 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 any
authorized Lexus dealer or
repairer, or anot her duly quali-
fied and equipped professional.
If your vehicle overheats
The following may indicate that your vehicle is overheating.
Correction procedures
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Page 612 of 676
6127-2. Steps to take in an emergency
LS600h/LS600hL_EE(OM50G20E)
The coolant level is satisfactory
if it is between the “FULL” and
“LOW” lines on the reservoir.
Reservoir
“FULL”
“LOW”
Add coolant if necessary.
( P. 493)
Water can be used in an emer-
gency if coolant is unavailable.
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2
3
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Page 613 of 676

6137-2. Steps to take in an emergency
7
When trouble arises
LS600h/LS600hL_EE(OM50G20E)
Start the hybrid system and turn the air conditioning system on to
check that the radiator cooling fan operates and to check for coolant
leaks from the radiator or hoses.
The fan operates when the air conditioning system is turned on immediately
after a cold start. Confirm that the fan is operating by checking the fan sound
and air flow. If it is difficult to check these, turn the air conditioning system on
and off repeatedly.
(The fan may not operate in freezing temperatures.)
If the fan is not operating:
Stop the hybrid system immediat ely and contact any authorized
Lexus dealer or repairer, or another duly qualified and equipped pro-
fessional.
If the fan is operating:
Have the vehicle inspected at the nearest any authorized Lexus
dealer or repairer, or another duly qualified and equipped profes-
sional.
■If “Hybrid System Overheat” is shown on the multi-information dis-
play
Stop the vehicle in a safe place.
Stop the hybrid system an d carefully lift the hood.
After the hybrid system has
cooled down, inspect the
hoses and radiator core (radia-
tor) for any leaks.
Radiator
Cooling fans
If a large amount of coolant
leaks, immediately contact any
authorized Lexus dealer or
repairer, or anot her duly quali-
fied and equipped professional.
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7
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2
3
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Page 614 of 676
6147-2. Steps to take in an emergency
LS600h/LS600hL_EE(OM50G20E)
The coolant level is satisfactory
if it is between the “F” and “L”
lines on the reservoir.
Reservoir
“F”
“L”
Add coolant if necessary.
( P. 493)
Water can be used in an emer-
gency if coolant is unavailable.
Start the hybrid system and check for the multi-information display.
If the message does not disappear:
Stop the hybrid system and contact any authorized Lexus dealer or
repairer, or another duly qualified and equipped professional.
If the message is not displayed:
Have the vehicle inspected at the nearest any authorized Lexus
dealer or repairer, or another duly qualified and equipped profes-
sional.
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1
2
3
5
6
Page 615 of 676

6157-2. Steps to take in an emergency
7
When trouble arises
LS600h/LS600hL_EE(OM50G20E)
CAUTION
■When inspecting under the hood of your vehicle
Observe the following precautions.
Failure to do so may result in serious injury such as burns.
●If steam is seen coming from under the hood, do not open the hood until the
steam has subsided. The engine compartment may be very hot.
●After the hybrid system has been turned off, check that the indicator on the
power switch and the “READY” indicator are off.
When the hybrid system is operating, the gasoline engine may automatically
start, or the cooling fan may suddenly operate even if the gasoline engine stops.
Do not touch or approach rotating parts such as the fan, which may lead to fin-
gers or clothing (especially a tie, a scarf or a muffler) getting caught, resulting in
serious injury.
NOTICE
■When adding engine/power control unit coolant
Add coolant slowly after the hybrid system has cooled down sufficiently. Adding
cool coolant to a hot hybrid system too quickly can cause damage to the hybrid
system.
■To prevent damage to the cooling system
Observe the following precautions:
●Avoid contaminating the coolant with foreign matter (such as sand or dust etc.).
●Do not use any coolant additive.
●Do not loosen the coolant reservoir caps
while the hybrid system and radiator are
hot.
High temperature steam or coolant could
spray out.
Page 616 of 676
6167-2. Steps to take in an emergency
LS600h/LS600hL_EE(OM50G20E)
Stop the hybrid system. Set the parking brake and shift the shift lever to
P.
Remove the mud, snow or sand from around the rear wheels.
Place wood, stones or some other material under the rear wheels to
help provide traction.
Restart the hybrid system.
Shift the shift lever to D or R and release the parking brake. Then, while
exercising caution, depress the accelerator pedal.
■When it is difficult to free the vehicle
If the vehicle becomes stuck
Carry out the following procedures if the tires spin or the vehicle
becomes stuck in mud, dirt or snow:
Press to turn off TRC.
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