coolant temperature TOYOTA PRIUS PRIME 2021 Owners Manual (in English)

PRIUS PRIME_OM_OM47D71U_(U)
2033. Instrument cluster
3
Instrument cluster
*1: These lights turn on when the power switch is turned to ON mode to indi-
cate that a system check is being performed. They will turn off after the
hybrid system is on, or after a few seconds. There may be a malfunction in
a system if a light does not come on, or turn off. Have the vehicle
inspected by your Toyota dealer.
*2: The light flashes or illuminates to indicate a malfunction.
*3: The light flashes to indicate a malfunction.
*1High coolant temperature warning light P. 676
*1, 3PKSB OFF indicator (if equipped) P. 676
Open door warning light P. 676
Low fuel level warning light P. 676
Driver’s and front passenger’s seat belt
reminder lightP. 677
Rear passengers’ seat belt reminder light
(U.S.A.)P. 677
Rear passengers’ seat belt reminder light
(Canada)P. 677
*1Master warning light P. 677
*1Tire pressure warning lightP. 677
Warning lightsPages

208
PRIUS PRIME_OM_OM47D71U_(U)
3. Instrument cluster
■BSM (Blind Spot Monitor) outside rear view mirror indicators
(if equipped) (P. 432)
• When the BSM function is enabled on the screen of the multi-infor-
mation display, the power switch is turned to ON mode.
If the system is functioning correctly, the BSM outside rear view mirror indi-
cators will turn off after a few seconds.
If the BSM outside rear view mirror indicators do not illuminate or do not
turn off, there may be a malfunction in the system.
If this occurs, have the vehicle inspected by your Toyota dealer. ●Indicators are also displayed on the out-
side rear view mirrors.
●In order to confirm operation, the BSM
outside rear view mirror indicators illumi-
nate in the following situations:
• When the power switch is in ON
mode, the BSM function is enabled
on the screen of the multi-infor-
mation display.
WARNING
■If a safety system warning light does not come on
Should a safety system light such as the ABS and SRS warning light not
come on when you start the hybrid system, this could mean that these sys-
tems are not available to help protect you in an accident, which could result
in death or serious injury. Have the vehicle inspected by your Toyota dealer
immediately if this occurs.
NOTICE
■To prevent damage to the engine and its components
The engine may be overheating if the high coolant temperature warning
light comes on or flashes. In this case, immediately stop the vehicle in a
safe place, and check the engine after it has cooled completely. (P. 721)

5186-1. Using the air conditioning system and defogger
PRIUS PRIME_OM_OM47D71U_(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 before driv-
ing (P. 535). 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 temperature 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_OM47D71U_(U)
5296-1. 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 before driv-
ing (P. 535). 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 temperature 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_OM47D71U_(U)
5957-3. Do-it-yourself maintenance
7
Maintenance and care
Tire inflation
pressure
(P. 623)• Tire pressure gauge
• Compressed air source
Washer fluid
(P. 6 1 2 )• Water or washer fluid containing antifreeze (for win-
ter use)
• Funnel (used only for adding water or washer fluid)
WARNING
The engine compartment contains many mechanisms and fluids that may
move suddenly, become hot, or become electrically energized. To avoid death
or serious injury, observe the following precautions.
■When working on the engine compartment
●Make sure that the “Accessory”, “Ignition ON” or mileage display
(P. 210) on the main display and the “READY” indicator are both off.
●Keep hands, clothing and tools away from the moving fan.
●Be careful not to touch the engine, power control unit, radiator, exhaust
manifold, etc. right after driving as they may be hot. Oil and other fluids
may also be hot.
●Do not leave anything that may burn easily, such as paper and rags, in the
engine compartment.
●Do not smoke, cause sparks or expose an open flame to fuel. Fuel fumes
are flammable.
●Be extremely cautious when working on the 12-volt battery. It contains poi-
sonous and corrosive sulfuric acid.
■When working near the electric cooling fans or radiator grille
Be sure the power switch is off.
With the power switch in ON mode, the electric cooling fans may automati-
cally start to run if the air conditioning is on and/or the coolant temperature
is high. (P. 606)
■Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc.
from getting in your eyes.
ItemsParts and tools

PRIUS PRIME_OM_OM47D71U_(U)
6057-3. Do-it-yourself maintenance
7
Maintenance and care
■Coolant selection
Only use “Toyota Super Long Life Coolant” or a similar high quality ethylene
glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with
long-life hybrid organic acid technology.
U.S.A.:
“Toyota Super Long Life Coolant” is a mixture of 50% coolant and 50% deion-
ized water. (Minimum temperature: -31F [-35C])
Canada:
“Toyota Super Long Life Coolant” is a mixture of 55% coolant and 45% deion-
ized water. (Minimum temperature: -44F [-42C])
For more details about coolant, contact your Toyota dealer.
■If the coolant level drops within a short time of replenishing
Visually check the radiator, hoses, engine/power control unit coolant reservoir
caps, drain cock and water pump.
If you cannot find a leak, have your Toyota dealer test the cap and check for
leaks in the cooling system.
WARNING
■When the hybrid system is hot
Do not remove the engine/power control unit coolant reservoir caps.
The cooling system may be under pressure and may spray hot coolant if the
cap is removed, causing serious injuries, such as burns.
NOTICE
■When adding coolant
Coolant is neither plain water nor straight antifreeze. The correct mixture of
water and antifreeze must be used to provide proper lubrication, corrosion
protection and cooling. Be sure to read the antifreeze or coolant label.
■If you spill coolant
Be sure to wash it off with water to prevent it from damaging parts or paint.

606
PRIUS PRIME_OM_OM47D71U_(U)
7-3. Do-it-yourself maintenance
Check the radiator and condenser and clear away any foreign objects.
If either of the above parts is extremely dirty or you are not sure of
their condition, have your vehicle inspected by your Toyota dealer.
Radiator and condenser
WARNING
■When the hybrid system is hot
Do not touch the radiator or condenser as they may be hot and cause seri-
ous injuries, such as burns.
■When the electric cooling fans are operating
Do not touch the engine compartment.
With the power switch in ON mode, the electric cooling fans may automati-
cally start to run if the air conditioning is on and/or the coolant temperature
is high. Be sure the power switch is off when working near the electric cool-
ing fans or radiator grille.

673
PRIUS PRIME_OM_OM47D71U_(U)
8
When trouble arises
8-2. Steps to take in an emergency
If you think something is wrong
●Fluid leaks under the vehicle
(Water dripping from the air conditioning after use is normal.)
●Flat-looking tires or uneven tire wear
●High coolant temperature warning light flashes or comes on
●Changes in exhaust sound
●Excessive tire squeal when cornering
●Strange noises related to the suspension system
●Pinging or other noises related to the hybrid system
●Engine missing, stumbling or running roughly
●Appreciable loss of power
●Vehicle pulls heavily to one side when braking
●Vehicle pulls heavily to one side when driving on a level road
●Loss of brake effectiveness, spongy feeling, pedal almost touches
the floor
If you notice any of the following symptoms, your vehicle proba-
bly needs adjustment or repair. Contact your Toyota dealer as
soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms

6768-2. Steps to take in an emergency
PRIUS PRIME_OM_OM47D71U_(U)
Slip indicator light
Indicates a malfunction in:
• The VSC system;
• The TRAC system; or
• The hill-start assist control system
Have the vehicle inspected by your Toyota dealer
immediately.
The light will flash when the ABS, VSC or TRAC system is
operating.
High coolant temperature warning light
• When the light flashes:
Indicates that the engine coolant temperature is too high
The light changes from a flashing to a solid light when
the temperature further increases
Immediately stop the vehicle in a safe place. (P. 721)
• When the light comes on without flashing:
Indicates a malfunction in the exhaust heat recirculator
system
Have the vehicle inspected by your Toyota dealer
immediately.
(Flashes)
(If equipped)
PKSB OFF indicator
Indicates a malfunction in the Parking Support Brake func-
tion
Have the vehicle inspected by your Toyota dealer.
The warning light will operate as follows, even when the
system is not malfunctioning:
• The light will come on when the Parking Support Brake
function is turned off (P. 456)
• The light will come on when the Parking Support Brake
function is operating (P. 460)
• The light will flash when the system cannot be temporar-
ily used (P. 464)
Open door warning light (warning buzzer)*3
Indicates that a door is not fully closed
Check that all the doors are closed.
Low fuel level warning light
Indicates that remaining fuel is approximately 1.7 gal.
(6.4 L, 1.4 Imp.gal.) or less
Refuel the vehicle.
Warning lightWarning light/Details/Actions

721
PRIUS PRIME_OM_OM47D71U_(U)
8
When trouble arises
8-2. Steps to take in an emergency
If your vehicle overheats
■If the high coolant temperature warning light comes on or
flashes
Stop the vehicle in a safe place and turn off the air conditioning
system, 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
your Toyota dealer.
The following may indicate that your vehicle is overheating.
●The high coolant temperature warning light (P. 676) comes on
or flashes, or a loss of hybrid system power is experienced. (For
example, the vehicle speed does not increase.)
●“Hybrid System Overheated” is shown on the multi-information
display.
●Steam comes out from under the hood.
Correction procedures
1
2
3
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