2010 TOYOTA PRIUS overheating

40 1-1. Hybrid system
PRIUS_U (OM47668U) U.S.A.
NOTICE
■Hybrid battery air vent
● Do not put foreign objects over the air vent. The hybrid battery (traction
battery) may overheat and be damaged.
● Clean the air vent regularly to prevent the hybrid battery (traction battery)
from overheating.
● Do not wet the air vent. It may cause a short circuit and damage the hybrid
battery (traction battery).
● Do not load a large amount of water such as an aquarium into the vehicle.
If water spills over the hybrid battery (traction battery), the battery may be
damaged.

159
2-1. Driving procedures
2
When driving
PRIUS_U (OM47668U) U.S.A.
CAUTION
■
When taking a nap in the vehicle
Always turn the hybrid system off. Otherwise, you may accidentally move the
shift lever or depress the accelerator pedal, which could cause an accident
or fire due to hybrid system overheating. Additionally, if the vehicle is parked
in a poorly ventilated area, exhaust gases may collect and enter the vehicle,
leading to death or a serious health hazard.
■ When braking the vehicle
● When the brakes are wet, drive more cautiously. 
Braking distance increases when the brakes are wet, and may cause one
side of the vehicle to brake differently than the other side. Also the parking
brake may not securely hold the vehicle.
● If the power brake assist function does not operate, do not follow other
vehicles closely and avoid downhill or sharp turns that require braking. 
In this case, braking is still possible, but it will require more force on the
pedal than usual. Braking distance may also increase.
● The brake system consists of 3 individual hydraulic systems: if one of the
systems fails, the other will still operate. In this case, the brake pedal
should be depressed more firmly than usual and braking distance
becomes longer. 
Do not drive your vehicle with only a single brake system. Have your
brakes fixed immediately.

179
2-1. Driving procedures
2
When driving
PRIUS_U (OM47668U) U.S.A.
Parking brake
■Usage in winter time
See “Winter driving tips” for parking brake usage in winter time. ( P. 261)
NOTICE
■Before driving
Fully release the parking brake. 
Driving the vehicle with the parking brake set will lead to brake components
overheating, which may affect braking performance and increase brake
wear.
■ When parking the vehicle
Before you leave the vehicle, set the parking brake, push the “P” position
switch and make sure that the vehicle does not move.
Sets the parking brake*
(Depressing the pedal again
releases the parking brake.)
*: Fully depress the parking
brake pedal with your left
foot while depressing the
brake pedal with your right
foot.
ITO21P116
CanadaU.S.A.

184 2-2. Instrument cluster
PRIUS_U (OM47668U) U.S.A.
Instrument panel light controlThe brightness of the instrument panel lights can be adjusted.
Brighter
Darker
ITO22P101
NOTICE
■To prevent damage to the hybr id system and its components
The hybrid system may be overheating if the high coolant temperature warn-
ing light comes on. In this case, immediately stop the vehicle in a safe place,
and check the hybrid system after it has cooled completely. ( P. 548)

247
2-4. Using other
driving systems
2
When driving
PRIUS_U (OM47668U) U.S.A.
■Reduced effectiveness of EPS
The effectiveness of EPS is reduced to prevent the system from overheating
when there is frequent steering input over an extended period of time. The
steering wheel may feel heavy as a result. Should this occur, refrain from
excessive steering input or stop the vehicle and turn the hybrid system off.
The system should return to normal within 10 minutes.
CAUTION
■The ABS does not opera te effectively when
● The limits of tire gripping performance have been exceeded.
● The vehicle hydroplanes while driving at high speed on the wet or slick
road.
■ Stopping distance when the ABS is ope rating on the wet or slick roads
The ABS is not designed to shorten the vehicle’s stopping distance. Always
maintain a safe distance from the vehicle in front of you in the following situ-
ations.
● When driving on dirt, gravel or snow-covered roads
● When driving with tire chains
● When driving over bumps in the road
● When driving over roads with potholes or roads with uneven pavement
■ TRAC may not operate effectively when
Directional control and power may not be achievable while driving on slip-
pery road surfaces, even if the TRAC is operating. 
Do not drive the vehicle in conditions where stability and power may be lost.

382 3-6. Other interior features
PRIUS_U (OM47668U) U.S.A.
CAUTION
■Burns
● Use caution when seating the following persons in a seat with the seat
heater on to avoid the possibility of burns:
• Babies, small children, the elderly, the sick and the disabled
• Persons with sensitive skin
• Persons who are fatigued
• Persons who have taken alcohol or drugs that induce sleep (sleeping
drugs, cold remedies, etc.)
● Do not cover the seat with anything when using the seat heater. 
Using the seat heater with a blanket or cushion increases the temperature
of the seat and may lead to overheating.
NOTICE
■ To prevent seat heater damage
Do not put unevenly weighted objects on the seat and do not stick sharp
objects (needles, nails, etc.) into the seat.
■ To prevent 12 volt battery discharge
Turn the switches off when the hybrid system is not operating.

5
When trouble arises
513
5-2. Steps to take in an emergency
PRIUS_U (OM47668U) U.S.A.
Warning messageDetailsCorrection
procedure
(If equipped) Indicates that the pre-collision
system is not currently func-
tional because the grille or the
sensor is dirty.
This message also appears
when the pre-collision system
is not functional due to over-
heating. Check the grille
and the sensor and
clean them if they
are dirty. In case of
overheating, the
system will become
functional once the
system cools
down.
(Flashing) 
(If equipped) Indicates that the radar cruise
control sensor is dirty or cov-
ered with ice.
Clean the sensor.
(Flashing) 
(If equipped) Indicates that the radar cruise
control system is unable to
judge vehicle-to-vehicle dis-
tance.
If the windshield
wipers are on, turn
them off or set
them to either the
intermittent or the
slow mode.

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