2023 TOYOTA HIGHLANDER HYBRID coolant reservoir

3966-3. Do-it-yourself maintenance
Engine coolant reservoir ( P.399)
Fuse boxes ( P.425)
Engine oil filler cap ( P.397)
Engine oil level dipstick ( P.397)
Brake fluid reservoir ( P.400)
Washer fluid tank ( P.401)
Electric cooling fan
Condenser ( P.400)
Radiator ( P.400)
Power control unit coolant reservoir ( P.399)
■12-volt battery
 P. 4 0 2
With the engine at operating
temperature and turned off,
check the oil level on the dip-
Engine compar tment
Components
Checking and adding the
engine oil

3996-3. Do-it-yourself maintenance
6
Maintenance and care■Engine coolant reservoir
The coolant level is satisfactory
if it is between the “FULL” and
“LOW” lines on the reservoir
when the engine is cold.
Reservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW”
line, add coolant up to the “FULL”
line. ( P.484)
■Power control unit coolant
reservoir
The coolant level is satisfactory
if it is between the “FULL” and
“LOW” lines on the reservoir
when the hybrid system is cold.
Reservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW”
line, add coolant up to the “FULL”
line. ( P.484)
■Coolant selection
Only use “Toyota Super Long Life
Coolant” or a similar high quality
ethylene glycol ba sed 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% c oolant and 50%
deionized water. (Minimum tem-
perature: -31°F [-35°C])
Canada:
“Toyota Super Long Life Coolant” is
a mixture of 55% c oolant and 45%
deionized water. (Minimum tem-
perature: -44°F [-42°C])
NOTICE
■When replacing the engine oil
●Be careful not to spill engine oil
on the vehicle components.
●Avoid overfilling, or the engine
could be damaged.
●Check the oil le vel on the dip-
stick every time you refill the
vehicle.
●Be sure the engine oil filler cap
is properly tightened.
■If oil is spilled on the engine
cover
To prevent the engine cover from
being damaged, remove any
engine oil from the engine cover
as soon as possible using a neu-
tral detergent. Do not use an
organic solvent such as brake
cleaner.
Checking the coolant

4006-3. Do-it-yourself maintenance
For more details about coolant, con-
tact 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 sys-
tem.
Check the radiator and con-
denser and clear away any for-
eign objects. If either of the
above parts is extremely dirty or you are not sure of their condi-
tion, have your vehicle
inspected by your Toyota dealer.
■Checking fluid level
The brake fluid level should be
between the “MAX” and “MIN”
lines on the tank.
■Adding fluid
Make sure to check the fluid
type and prepare the necessary
item.
 Fluid type
SAE J1703 or FMVSS No.116 DOT
3 brake fluid
SAE J1704 or FMVSS No.116 DOT
4 brake fluid
Item
Clean funnel
WARNING
■When the hybrid system is
hot
Do not remove the engine/power
control unit coolant reservoir caps
and radiator cap.
The cooling system may be under
pressure and may spray hot cool-
ant 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 d amaging parts or
paint.
Checking the radiator and
condenser
WARNING
■When the hybrid system is
hot
Do not touch the radiator or con-
denser as they may be hot and
cause serious injuries, such as
burns.
Checking and adding the
brake fluid

4857-2. Steps to take in an emergency
7
When trouble arises
the steam subsides.
If you do not see steam:
Carefully lift the hood.
3 After the hybrid system has
cooled down sufficiently,
inspect the hoses and radia-
tor core (radiator) for any
leaks.
Radiator
Cooling fan
If a large amount of coolant leaks,
immediately cont act your Toyota
dealer.
4 The coolant level is satisfac-
tory if it is between the
“FULL” and “LOW” lines on
the reservoir.
Reservoir
“FULL” line
“LOW” line Radiator cap
5 Add coolant if necessary.
Water can be used in an emer-
gency if coolant is unavailable.
6Start the hybrid system and
turn the air conditioning sys-
tem on to check that the radi-
ator cooling fan operates and
to check for coolant leaks
from the radiator or hoses.
The fan operates when the air con-
ditioning system is turned on imme-
diately after a cold start. Confirm
that the fan is operating by check-
ing the fan sound and air flow. If it is
difficult to check these, turn the air
conditioning system on and off
repeatedly. (The fan may not oper-
ate in freezing temperatures.)
7If the fan is not operating:
Stop the hybrid system
immediately and contact your
Toyota dealer.
If the fan is operating:
Have the vehicle inspected at
the nearest Toyota dealer.
8 Check if “Engine Coolant
Temp High Stop in a Safe
Place See Owner's Manual”
is shown on the multi-infor-
mation display.
If the message does not disappear:
Stop the hybrid system and contact

4867-2. Steps to take in an emergency
your Toyota dealer.
If the message is not displayed:
Have the vehicle inspected at the
nearest Toyota dealer.
If “Hybrid System Over-
heated Output Power
Reduced” is shown on the
multi-information display
1 Stop the vehicle in a safe
place.
2 Stop the hybrid system and
carefully lift the hood.
3 After the hybrid system has
cooled down, inspect the
hoses and radiator core (radi-
ator) for any leaks.
Radiator
Cooling fan
If a large amount of coolant leaks,
immediately cont act your Toyota
dealer.
4 The coolant level is satisfac-
tory if it is between the “FULL” and “LOW” lines on
the reservoir.
Reservoir
“FULL” line
“LOW” line
5 Add coolant if necessary.
Water can be used in an emer-
gency if coolant is unavailable.
6After stopping the hybrid sys-
tem and waiting for 5 minutes
or more, start the hybrid sys-
tem again and check if
“Hybrid System Overheated
Output Power Reduced” is
shown on the for the
multi-information display.
If the message does not disappear:
Stop the hybrid system and contact
your Toyota dealer.
If the message is not displayed:
The hybrid system temperature has
dropped and the vehicle may be
driven normally.

4877-2. Steps to take in an emergency
7
When trouble arises
However, if the message appears
again frequently, contact your Toy-
ota dealer.
WARNING
■When inspecting under the
hood of your vehicle
Observe the following precau-
tions.
Failure to do so may result in seri-
ous injury such as burns.
●If steam is seen coming from
under the hood, do not open the
hood until the steam has sub-
sided. The engine compart-
ment may be very hot.
●After the hybrid system has
been turned off, check that the
“READY” indicator is off.
When the hybrid system is oper-
ating, the gasoline engine may
automatically start, or the cool-
ing fan may suddenly operate
even if the gasoline engine
stops. Do not touch or approach
rotating parts such as the fan,
which may lead to fingers or
clothing (especially a tie, a scarf
or a muffler) getting caught,
resulting in serious injury.
●Do not loosen the radiator cap
and the coolant reservoir caps
while the hybrid system and
radiator are hot.
High temperature steam or
coolant could spray out.
NOTICE
■When adding engine/power
control unit coolant
Add coolant slowly after the
hybrid system has cooled down
sufficiently. Adding cool coolant to
a hot hybrid system too quickly
can cause damage to the hybrid
system.
■To prevent damage to the
cooling system
Observe the following precau-
tions:
●Avoid contaminating the coolant
with foreign matter (such as
sand or dust, etc.).
●Do not use any coolant additive.