
498
PRIUS PRIME_OM_OM47E74U_(U)
5-5. Using the driving support systems
■Turning off both TRAC and VSC systems
To turn the TRAC and VSC systems off, press and hold for more than 3
seconds while the vehicle is stopped.
The VSC OFF indicator will come on and the “Traction Control Tu rned Off”
will be shown on the multi-information display.
*
Press again to turn the systems back on.
*: Pre-collision brake assist and pre-collision braking will also be disabled.
The PCS warning light will come on and the message will be show n on the
multi-information display. ( P. 6 7 2 )
■ When the message is displayed on the multi-information display show-
ing that TRAC has been disab led even if has not been pressed
TRAC is temporary deactivated. If the information continues to show, contact
your Toyota dealer.
■ Operating conditions of hill-start assist control
When the following four conditions are met, the hill-start assi st control will
operate:
● The shift position is in a position other than P or N (when sta rting off forward/
backward on an upward incline)
● The vehicle is stopped
● The accelerator pedal is not depressed
● The parking brake is not engaged
■ Automatic system cancelation of hill-start assist control
The hill-start assist control will turn off in any of the following situations:
● Shift the shift position to P or N
● The accelerator pedal is depressed
● The parking brake is engaged
● No more than 2 seconds have elapsed after the brake pedal is re leased.
■ Sounds and vibrations caused by the ABS, brake assist, VSC, TRAC and
hill-start assist control systems
●A sound may be heard from the engine compartment when the brake pedal
is depressed repeatedly, when the hybrid system is started or just after the
vehicle begins to move. This sound does not indicate that a mal function has
occurred in any of these systems.
● Any of the following conditions may occur when the above system s are
operating. None of these indicates that a malfunction has occur red.
• Vibrations may be felt through the vehicle body and steering.
• A motor sound may be heard also after the vehicle comes to a s top.

PRIUS PRIME_OM_OM47E74U_(U)
4995-5. Using the driving support systems
5
Driving
■ECB operating sound
ECB operating sound may be heard in the following cases, but it does not
indicate that a malfunction has occurred.
● Operating sound heard from the engine compartment when the brak e pedal
is operated.
● Motor sound of the brake system heard from the front part of th e vehicle
when the driver’s door is opened.
● Operating sound heard from the engine compartment when one or t wo min-
utes passed after the stop of the hybrid system.
■ EPS operation sound
When the steering wheel is operated, a motor sound (whirring so und) may be
heard. This does not indicate a malfunction.
■ Automatic reactivation of TRAC and VSC systems
After turning the TRAC and VSC systems off, the systems will be automati-
cally re-enabled in the following situations:
● When the power switch is turned off
● If only the TRAC system is turned off, the TRAC will turn on wh en vehicle
speed increases
If both the TRAC and VSC systems are turned off, automatic re-e nabling
will not occur when vehicle speed increases.
■ Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the s ystem from
overheating when there is frequent steering input over an exten ded period of
time. The steering wheel may feel heavy as a result. Should thi s occur, refrain
from excessive steering input or stop the vehicle and turn the hybrid system
off. The EPS system should return to normal within 10 minutes.
■ Electric power steering system wa rning light (warning buzzer)
P. 672

502
PRIUS PRIME_OM_OM47E74U_(U)
5-6. Driving tips
Winter driving tips
●Use fluids that are appropriate t o the prevailing outside tempera-
tures. • Engine oil
• Engine/power control unit coolant
• Washer fluid
● Have a service technician inspect the condition of the 12-volt bat-
tery.
● Have the vehicle fitted with four snow tires or purchase a set of tire
chains for the front tires.
Ensure that all tires are the same size and brand, and that cha ins match
the size of the tires.
Perform the following accordi ng to the driving conditions:
● Do not try to forcibly open a window or move a wiper that is fr ozen.
Pour warm water over the frozen area to melt the ice. Wipe away
the water immediately to p revent it from freezing.
● To ensure proper operation of the climate control system fan,
remove any snow that has accumulated on the air inlet vents in
front of the windshield.
● Check for and remove any excess ic e or snow that may have accu-
mulated on the exterior lights, vehicle’s roof, chassis, around the
tires or on the brakes.
● Remove any snow or mud from the bottom of your shoes before
getting in the vehicle.
Carry out the necessary preparations and inspections before
driving the vehicle in winter. Always drive the vehicle in a ma n-
ner appropriate to the prevailing weather conditions.
Preparation for winter
Before driving the vehicle

504
PRIUS PRIME_OM_OM47E74U_(U)
5-6. Driving tips
■Tire chain installation
Observe the following precautions when installing and removing chains:
● Install and remove tire chains in a safe location.
● Install tire chains on the front tires only. Do not install tir e chains on the rear
tires.
● Install tire chains on front tires as tightly as possible. Retighten chains after
driving 1/4 - 1/2 mile (0.5 - 1.0 km).
● Install tire chains following the instructions provided with the tire chains.
■ Consumption of fuel and electricity
In cold temperatures, resistance of the parts of a vehicle (transmission, tires,
etc.) generally increases, resulting in increase of energy consumption. As a
result, fuel economy is likely to decrease.
Consumption of fuel and electricity of this vehicle is also likely to become
worse in cold temperatures.
WARNING
■Driving with snow tires
Observe the following precautions to reduce the risk of accidents.
Failure to do so may result in a loss of vehicle control and ca use death or
serious injury.
● Use tires of the specified size.
● Maintain the recommended level of air pressure.
● Do not drive in excess of 75 mph (120 km/h), regardless of the type of
snow tires being used.
● Use snow tires on all, not just some wheels.
■ Driving with tire chains
Observe the following precautions to reduce the risk of accidents.
Failure to do so may result in the vehicle being unable to be d riven safely,
and may cause death or serious injury.
● Do not drive in excess of the speed limit specified for the tir e chains being
used, or 30 mph (50 km/h), whichever is lower.
● Avoid driving on bumpy road surfaces or over potholes.
● Avoid sudden acceleration, abrupt steering, sudden braking and shifting
operations that cause sudden engine braking.
● Slow down sufficiently before entering a curve to ensure that vehicle con-
trol is maintained.
● Do not use LTA (Lane Tracing Assist).
■ When parking the vehicle
When parking the vehicle without applying the parking brake, ma ke sure to
chock the wheels. If you do not chock the wheels, the vehicle m ay move
unexpectedly, possibly resulting in an accident.

5146-1. Using the air conditioning system and defogger
PRIUS PRIME_OM_OM47E74U_(U)
■Heating
●In HV mode, the gasoline engine may operate in order to extract heat from
the engine coolant via the heater.
● In EV mode, heating is done by a heat pump system.
• When the outside temperature is low or it is snowing, compared to con-
ventional vehicles, heating may be less effective and warm air may not
come out.
• If frost has formed on the outside heat exchanger, the heating perfor-
mance will decline. The frost can be removed from the outside heat
exchanger by operating the Remote Air Conditioning System befor e driv-
ing ( P. 531). When frosted over, the heating operation of the Remote
Air Conditioning System starts after defrosting.
• When is turned on, the heating is controlled optimally. Therefore, the set heating performance may not be achieved even if the fan speed
setting is increased.
● In the following situations the gasoline engine may operate in order to
extract heat from the engine coolant via the heater even in EV mode.
• The outside temperature is approximately 14°F (-10°C) or low
• is operating
■ Using automatic mode
Fan speed is adjusted automatically according to the temperatur e setting and
the ambient conditions.
Therefore, the fan may stop for a while until warm or cool air is ready to flow
immediately after is pressed.
■ Water droplets during air conditioning operation• When the outside heat exchanger is
frosted over, fan speed declines and it
may become harder to heat the inte-
rior. However, it is not a malfunction.
In this situation, the air temperature
from the outlets may not change even
though the set temperature is raised.
The outside heat exchanger, accumulator
and air conditioning piping may incur con-
densation or frost may form. During or
after the air conditioning operation, water
droplets may fall from the vehicle. How-
ever, it is not a malfunction.
Outside heat exchanger
Outside heat exchanger
Accumulator

5166-1. Using the air conditioning system and defogger
PRIUS PRIME_OM_OM47E74U_(U)■
Fogging up of the windows
●The windows will easily fog up when the humidity in the vehicle is high.
Turning on will dehumidify the air from the outlets and defog the
windshield effectively.
● If you turn off, the windows may fog up more easily.
● The windows may fog up if the recirculated air mode is used.
■ Windshield fog detection function
When automatic mode is set, the humidity sensor (P. 519) detects fog on
the windshield and controls the air conditioning system to prev ent fog.
■ When driving on dusty roads
Close all windows. If dust thrown up by the vehicle is still drawn into the vehi-
cle after closing the windows, it is recommended that the air intake mode be
set to outside air mode and the fan speed to any setting except off.
■ Outside/recirculated air mode
●Setting to the recirculated air mode temporarily is recommended in prevent-
ing dirty air from entering the vehicle interior and helping to cool the vehicle
when the outside air temperature is high.
● Outside/recirculated air mode may automatically switch dependin g on the
temperature setting or the inside temperature.
■ Fresh air intake system while parking
When parking, the system automatically switches to outside air mode to
encourage better air circulation throughout the vehicle, helpin g to reduce
odors that occur when starting the vehicle.
■ Operation of the air conditioning system in the air conditionin g eco
mode
● In the air conditioning eco mode, the air conditioning system i s controlled as
follows to prioritize fuel efficiency:
• Engine speed and compressor operation controlled to restrict h eating/
cooling capacity
• Fan speed restricted when automatic mode is selected
● To improve air conditioning performance, perform the following operations:
• Adjust the fan speed
• Adjust the temperature setting
• Turn off the air conditioning eco mode
● When the driving mode is set to Eco driving mode, the air condi tioning eco
mode will be turned on automatically. Even in this case, the ai r conditioning
eco mode can be turned off by pressing . ( P. 425)
■ When the outside tempera ture falls to nearly 32F (0 C)
The dehumidification function may not operate even when is pressed.

PRIUS PRIME_OM_OM47E74U_(U)
5256-1. Using the air conditioning system and defogger
6
Interior features
■Heating
●In HV mode, the gasoline engine may operate in order to extract heat from
the engine coolant via the heater.
● In EV mode, heating is done by a heat pump system.
• When the outside temperature is low or it is snowing, compared to con-
ventional vehicles, heating may be less effective and warm air may not
come out.
• If frost has formed of the outside heat exchanger, the heating perfor-
mance will decline. The frost can be removed from the outside heat
exchanger by operating the Remote Air Conditioning System befor e driv-
ing ( P. 531). When frosted over, the heating operation of the Remote
Air Conditioning System starts after defrosting.
• When is turned on, the heating is controlled optimally. There -
fore, the set heating performance may not be achieved even if the fan
speed setting is increased.
● In the following situations the gasoline engine may operate in order to
extract heat from the engine coolant via the heater even in EV mode.
• The outside temperature is approximately 14°F (-10°C) or low
• is operating
■ Using automatic mode
Fan speed is adjusted automatically according to the temperatur e setting and
the ambient conditions.
Therefore, the fan may stop for a while until warm or cool air is ready to flow
immediately after is pressed.
■ Water droplets during air conditioning operation• When the outside heat exchanger is
frosted over, fan speed declines and it
may become harder to heat the inte-
rior. However, it is not a malfunction.
In this situation, the air temperature
from the outlets may not change even
though the set temperature is raised.
The outside heat exchanger, accumulator
and air conditioning piping may incur con-
densation or frost may form. During or
after the air conditioning operation, water
droplets may fall from the vehicle. How-
ever, it is not a malfunction.
Outside heat exchanger
Outside heat exchanger
Accumulator

PRIUS PRIME_OM_OM47E74U_(U)
5276-1. Using the air conditioning system and defogger
6
Interior features
■Windshield fog detection function
When automatic mode is set, the humidity sensor (P. 530) detects fog on
the windshield and controls the air conditioning system to prev ent fog.
■ When driving on dusty roads
Close all windows. If dust thrown up by the vehicle is still drawn into the vehi-
cle after closing the windows, it is recommended that the air intake mode be
set to outside air mode and the fan speed to any setting except off.
■ Outside/recirculated air mode
●Setting to the recirculated air mode temporarily is recommended in prevent-
ing dirty air from entering the vehicle interior and helping to cool the vehicle
when the outside air temperature is high.
● Outside/recirculated air mode may automatically switch dependin g on the
temperature setting or the inside temperature.
■ Fresh air intake system while parking
When parking, the system automatically switches to outside air mode to
encourage better air circulation throughout the vehicle, helpin g to reduce
odors that occur when starting the vehicle.
■ Operation of the air conditioning system in the air conditionin g eco
mode
● In the air conditioning eco mode, the air conditioning system i s controlled as
follows to prioritize fuel efficiency:
• Engine speed and compressor operation controlled to restrict h eating/
cooling capacity
• Fan speed restricted when automatic mode is selected
● To improve air conditioning performance, perform the following operations:
• Adjust the fan speed
• Adjust the temperature setting
• Turn off the air conditioning eco mode
● When the driving mode is set to Eco driving mode, the air condi tioning eco
mode will be turned on automatically. Even in this case, the ai r conditioning
eco mode can be turned off by selecting . ( P. 425)
■ When the outside tempera ture falls to nearly 32F (0 C)
The dehumidification function may not operate even when is
selected.
■ When the outside temperature exceeds 75°F (24°C) and the air co ndition-
ing system is on
● In order to reduce the air conditioning power consumption, the air condition-
ing system may switch to recirculated air mode automatically. This may also
reduce fuel consumption.
● Recirculated air mode is selected as a default mode when the power switch
is turned to ON mode.
● It is possible to switch to outside air mode at any time by pressing
.