2010 TOYOTA PRIUS Owners Manual

5
When trouble arises
545
5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
■
Starting the hybrid system when the 12 volt battery is discharged
The hybrid system cannot be started by push-starting. In addition, the shift
position may not changed from “P”.
■ Avoiding a discharged 12 volt battery
● Turn off the headlights and the audio system while the hybrid system is
turned off.
● Turn off any unnecessary electrical components when the vehicle is run-
ning at a low speed for an extended period, such as in heavy traffic, etc.
■ When the 12 volt battery is removed or discharged
The hybrid system may not start. (
P. 438)
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.
Turn the “POWER” switch to ACCESSORY mode.
Maintain the engine speed on the second vehicle and turn
the “POWER” switch to ON mode, then start your vehicle’s
hybrid system.
Make sure the “READY” indicator comes on. If the indicator
does not come on, contact your Toyota dealer.
Once the vehicle’s hybrid syst em has started, remove the
jumper cables in the exact reverse order in which they were
connected.
Once the hybrid system starts, ha ve the vehicle checked at your
Toyota dealer as soon as possible.STEP4
STEP5
STEP6
STEP7
STEP8

546 5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
CAUTION
■Avoiding 12 volt battery fires or explosions
Observe the following precautions to prevent accidentally igniting the flam-
mable gas that may be emitted from the 12 volt battery.
● Make sure the jumper cable is connected to the correct terminal and that it
is not unintentionally in contact with any part other than the intended termi-
nal.
● Do not allow the jumper cables to come into contact with the “+” and “-” ter-
minals.
● Do not allow open flame or use matches , cigarette lighters or smoke 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 pre-
cautions 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 come 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,
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 battery support, terminals, and
other battery-related parts.
● Do not allow children near the 12 volt battery.

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When trouble arises
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5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
NOTICE
■
To prevent damaging the vehicle
The exclusive jump starting terminal 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.
■ When handling jumper cables
Be careful that the jumper cables do not become tangled in the cooling fan
or any of the belts when connecting or disconnecting them.

548
5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
If your vehicle overheats
Correction procedures■ If the high coolant temperatur e warning light comes on or
flashes
Stop the vehicle in a safe place and turn off the air condition-
ing system.
Check to see if steam is coming out from under the hood.
If you see steam: 
Stop the hybrid system. Carefully lift 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.
The following may indicate that your vehicle is overheating:
● The high coolant temperature warn ing light comes on or flashes:
The engine may be overheating.
● “HYBRID SYSTEM OVERHEAT” is shown on the multi-informa-
tion display: 
The power control unit may be overheating.
Follow the correction procedure as described below.
STEP1
STEP2

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When trouble arises
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5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
Check to see if the cooling fans are operating.
If the fans are operating: 
Wait until the high coolant temperature warning light goes
off and then stop the hybrid system.
If the fans are not operating:  Stop the hybrid system immedi ately and call your local
Toyota dealer.
After the hybrid system has
cooled down sufficiently, check
the engine coolant level and
inspect the radiator core (radia-
tor) for any leaks.
If necessary, add engine coolant
up to the “FULL” line.
Water can be used in an emer-
gency measure if engine coolant
is unavailable. (P. 562)
STEP3
STEP4
ITO52P130
STEP5

550 5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.■
If “HYBRID SYSTEM OVERHEAT” is shown on the multi-infor-
mation display
Stop the vehicle in a safe place and turn off the air condition-
ing system.
Leave the hybrid system operating and carefully lift the hood.
Check if the cooling fans are operating.
If the fans are operating: 
Wait until “HYBRID SYSTEM OVERHEAT” disappears and
then stop the hybrid system. 
If the message does not disapp ear, call your Toyota dealer.
If the fans are not operating: 
Stop the hybrid system immediately and call your Toyota
dealer.
After the hybrid system has
cooled down, check the power
control unit coolant level and
inspect the cooling system for
leaks.
STEP1
STEP2
STEP3
STEP4

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When trouble arises
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5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
If necessary, add power control
unit coolant up to the full line.
Water can be used in an emer-
gency measure if power control
unit coolant is unavailable.

( P. 562)
Have the vehicle checked at nearest Toyota dealer as soon as possi-
ble.
STEP5
■ Overheating
The following symptoms may occur when your vehicle is overheating:
● Hybrid system output decrease.
● Steam is coming from under the hood.

552 5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
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 compartment may be very hot, caus-
ing serious injury such as burns.
● With a hybrid vehicle, there are times when the gasoline engine automati-
cally 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 an accidental injury.
● Do not loosen the coolant reservoir cap while the hybrid system and radia-
tor are hot. 
Serious injury, such as burns, may result 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 sys-
tem too quickly can cause damage to the hybrid system.