2010 Lexus HS250h Basic Information Before Operation / LEXUS 2010 HS250H OWNERS MANUAL (OM75006U)

5
When trouble arises
537
5-2. Steps to take in an emergency
Connect the jumper cables according to the following procedure:
Connect a positive jumper cable clamp to the exclusive jump start-
ing terminal on your vehicle
Connect the clamp on the other end of the positiv
e cable to the pos-
itive (+) battery terminal on the second v
ehicle
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,
stationary, unpainted metallic point aw
ay from the exclusive jump
starting terminal and any moving part s, as shown in the illustration.
Start the engine of the second v
ehicle. Increase the engine
speed slightly and maintain that le
vel for approximately 5 min-
utes to recharge the 12-volt battery of your vehicle.
Maintain the engine sp eed of the second v
ehicle 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 your Lexus dealer.
Once the hybrid system has star
ted, remove the jumper cables
in the exact reverse order from which they were connected.

538
5-2. Steps to take in an emergency
■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 discharged
●The hybrid system may not start. (P. 4 3 4 )
●If the 12-volt battery is depleted with the shift position in P, it will not be possible
to shift out of P. In this case, the vehi cle cannot be towed without lifting both
front wheels because the front wheels are locked by the parking lock. 
(  P. 4 8 3 )
●When the 12-volt battery is reconnected, start the hybrid system, depress the
brake pedal, and confirm that it is poss ible to shift into each shift position.
Close the exclusive jump starting terminal cover and reinstall
the fuse box cover.
Once the hybrid system starts, have the vehicle inspected at your
L
exus dealer as soon as possible.

5
When trouble arises
539
5-2. Steps to take in an emergency
CAUTION
■Avoiding battery fires or explosions
The flammable gas that may be generated by the assisting vehicle battery may
catch fire and explode. Make sure to observe the following to prevent fire or sparks.
●Make sure each jumper cable is connected to the correct terminal and that it is
not unintentionally in contact with any part 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 ju mper cables to come into contact with
each other.
●Do not allow open flame or use matches, cigarette lighters or smoke near the
battery.
■12-volt battery precautions
The 12-volt battery contains poisonous and corrosive acidic electrolyte, while
related parts contain lead and lead comp ounds. Observe the following precautions
when handling 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 co me into 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, immedi-
ately 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 battery support, terminals, and other
battery-related parts.
●Do not allow children near the 12-volt battery.

540
5-2. Steps to take in an emergency
NOTICE
■Exclusive jump starting terminal precaution
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 vehi-
cle.
■When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in
the cooling fans or belt.

5
When trouble arises
541
5-2. Steps to take in an emergency
If your vehicle overheats
Correction procedures
■If the engine coolant temperature warning light comes on or flashes
Stop the vehicle in a safe place an d turn of
f the air conditioning
system.
Check to see if steam is coming out from the engine area.
If you see steam: 
Stop the hybrid system. Carefu lly lif
t the hood after the steam
subsides and then restart the hybrid system.
If you do not see steam:
Leave the hybrid system operating and carefully lift the hood.
Remove the engine compartment cover. ( P. 4 2 3 )
Check to see if the cooling fans are operating.
If the fans are operating: 
Wait until the high engine coolant temperature warning light goes
of
f 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:
●The high engine coolant temperature warning light comes on or
flashes: 
The engine may be overheating.
● “HYBRID S
YSTEM OVERHEAT” is sh own on the multi-information
display: 
The power control unit may be overheating.
Follow the correction procedure as described below.

542
5-2. Steps to take in an emergency
After the hybrid system has cooled
down sufficiently, check the engine
coolant level and inspect the cool-
ing system for leaks.
Add engine coolant if necessary.
Water can be used in an emer -
gency if engine coolant is unavail -
able. ( P. 5 5 2 )
Have the vehicle inspected at the ne arest Lexus dealer as soon as possi-
ble.
■ If “HYBRID S
YSTEM OVERHEAT” is shown on the multi-informa -
tion display
Stop the vehicle in a safe place an d turn of
f the air conditioning
system.
Leave the hybrid system operating and carefully lift the hood.
Remove the engine compartment covers. ( P. 4 2 3 )
Check if the cooling fans are operating.
If the fans are operating: 
Wait until the “HYBRID SYST EM O
VERHEAT” message disap-
pears and then stop the hybrid system. 
If the message does not disappear, call your Lexus dealer.
If the fans are not operating: 
Stop the hybrid system immediately and call your Lexus dealer.

5
When trouble arises
543
5-2. Steps to take in an emergency
After the hybrid system has cooled
down, check the power control
unit coolant level and inspect the
cooling system for leaks.
Add power control unit coolant if
nec
essary.
Water can be used in an emer -
gency if power control unit coolant
is una
vailable. ( P. 5 5 2 )
Have the vehicle inspected at the ne arest Lexus dealer as soon as possi-
ble.
■Overheating
The following symptoms may occur wh en
your vehicle is overheating:
●The high engine coolant temperature warn ing light comes on or flashes, or the
hybrid system output decreases.
●Steam comes out from the engine area.
●“HYBRID SYSTEM OVERHEAT” is displayed on the multi-information display.

544
5-2. Steps to take in an emergency
CAUTION
■To prevent an accident or injury when inspecting under the hood of your vehicle
●If steam is seen coming from under the hood, do not open the hood until the
steam has subsided. The engine compartm ent may be very hot, causing serious
injuries such as burns.
●Check that the indicator on the “POWER ” switch and the READY indicator are
off.
●For vehicles with a hybrid system, there are times when the gasoline engine auto-
matically starts to run or the cooling fans suddenly start to operate. Do not touch
or approach the rotating parts of the belt or fans. Doing so may lead to fingers,
clothes or tools getting caught, resulting in injury.
●Do not loosen the coolant reservoir cap while the hybrid system and radiator are
hot. 
Serious injuries, such as burns, may resu lt from hot coolant and steam released
under pressure.
NOTICE
■When adding engine/power control unit coolant
Wait until the hybrid system has cooled down before adding engine/power control
unit coolant. 
When adding coolant, do so slowly. Adding cool coolant to a hot hybrid system too
quickly can cause damage to the hybrid system.