cooling LEXUS RX450h 2015 User Guide

6504-3. Do-it-yourself maintenance
CAUTIONThe engine compartment contains many mechanisms and fluids that may move sud-
denly, 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 indicator on the “POWER” switch and the “READY” indicator
are both off.●
Keep hands, clothing and tools away from the moving fans and engine drive belt.●
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 easi ly, such as paper and rags, in the engine
compartment.●
Do not smoke, cause sparks or expose an open flame to fuel. Fuel fumes are flam-
mable■
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. 6 6 1 )■
Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc. from getting
in your eyes.
NOTICE■
If you remove the air cleaner filter
Driving with the air cleaner filter removed may cause excessive engine wear due to
dirt in the air.

6544-3. Do-it-yourself maintenance
Engine compartment
Brake fluid reservoir
(  P. 6 6 2 )
Engine oil filler cap
(  P. 6 5 7 )
Engine oil level dipstick
(  P. 6 5 6 )
Power control unit coolant
reservoir (  P. 6 5 9 )
Fuse boxes (  P. 6 8 9 ) Engine coolant reservoir
(  P. 6 5 9 )
Condenser (  P. 6 6 1 )
Radiator (  P. 6 6 1 )
Electric cooling fans
Power control unit coolant
radiator (  P. 6 6 1 )
Washer fluid tank (  P. 663)

6604-3. Do-it-yourself maintenance
Power control unit coolant reservoir
Reservoir cap
“FULL” line
“LOW” line If the level is on or below the
“LOW” line, add coolant up to the
“FULL” line. (  P. 788)
■
Coolant selection
Only use “Toyota Super Long Life Coolant” or 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% deionized water. (Minimum temperature: -31  F [-35  C])
Canada: “Toyota Super Long Life Coolant” is a mixture of 55% coolant and 45%
deionized water. (Minimum temperature: -44  F [-42  C])
For more details about coolant, contact your Lexus dealer.
■
If the coolant level drops within a short time of replenishing
Visually check the radiators, hoses, engine/power control unit coolant reservoir
caps, drain cock and water pump.
If you cannot find a leak, have your Lexus dealer test the cap and check for leaks in
the cooling systems.

6614-3. Do-it-yourself maintenance
4
Maintenance and care
Radiator and condenser
Check the radiator and condenser an d clear away any foreign objects.
If either of the above parts are extremely dirty or you are not sure of their
condition, have your vehicle checked by your Lexus dealer. CAUTION■
When the engine and hybrid system are hot
Do not remove the coolant reservoir cap.
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 damaging to parts or paint.
CAUTION■
When the hybrid system is hot
Do not touch the radiator or condenser as they may be hot and cause serious inju-
ries, such as burns.

6954-3. Do-it-yourself maintenance
4
Maintenance and care ■ Engine compartment (type B fuse box)
Fuse Ampere Circuit1
RR DEF 50 A Rear window defogger2
AIR SUS 50 A3
HEATER 50 A Air conditioning system4
ABS NO. 1 50 A Electronically controlled brake system5
RDI FAN NO. 1 40 A Electric cooling fans6
RDI FAN NO. 2 40 A Electric cooling fans7
H-LP CLN 30 A Headlight cleaner8
PBD 30 A Power back door9
HV R/B NO. 1 30 A PCU, IGCT NO. 2, IGCT NO. 3,
INV W/P
10
PD 50 A A/F, H-LP RH HI, H-LP LH LO, H-LP
RH LO, H-LP LH HI, HORN, S-
HORN
11
ABS NO. 2 50 A Electronically controlled brake system
12
HV R/B NO. 2 80 A ABS MAIN NO. 1, ABS MAIN NO.
2, A/C W/P, BATT FAN, OIL PMP

6984-3. Do-it-yourself maintenance
35
ECU-IG1 NO. 4 10 A Air conditioning system, rear window
defogger, electronically controlled
brake system, electric cooling fans36
BK/UP LP 7. 5 A Back-up lights37
ECU-IG1 NO. 5 15 A Air conditioning system38
ECU-IG1 NO. 6 10 A Head light cleaner, cruise control, air
conditioning system, Blind Spot Moni-
tor39
EFI NO. 2 10 A Multiport fuel injection system/
sequential multiport fuel injection sys-
tem40
F/ P M P 15 A Multiport fuel injection system/
sequential multiport fuel injection sys-
tem41
DEICER 25 A Windshield wipers and washer
42
STOP 7. 5 A Vehicle Proximity Notification System,
vehicle dynamics integrated manage-
ment, stop lights, multiport fuel injec-
tion system/sequential multiport fuel
injection system, shift lock control sys-
tem, starter system, cruise control43
TOW I N G BAT T 20 A44
TOW I N G 30 A Trailer lights45
FILTER 10 A
46
IG1 MAIN 30 A ECU-IG1 NO. 6, BK/UP LP, ECU-
IG1 NO. 5, ECU-IG1 NO. 4
47
H-LP RH HI 15 A Right-hand headlight (high beam)
48
H-LP LH HI 15 A Left-hand headlight (high beam)Fuse Ampere Circuit

6994-3. Do-it-yourself maintenance
4
Maintenance and care
■ Engine compartment (type C fuse box) 49
BIXENON 10 A50
H-LP RH LO 15 A Right-hand headlight (low beam)51
H-LP LH LO 15 A Left-hand headlight (low beam)52
HORN 10 A Horn53
A/F 20 A Multiport fuel injection system/
sequential multiport fuel injection sys-
tem54
S-HORN 7. 5 A S-HORN
Fuse Ampere Circuit1
ABS MAIN NO. 1 10 A Brake system
2
ABS MAIN
NO. 2 10 A Brake system
3
BATT FAN 15 A Battery cooling fan
4
OIL PMP 10 A Hybrid system
5
A/C W/P 10 A Air conditioning systemFuse Ampere Circuit

5
When trouble arises
7875-2. Steps to take in an emergency
CAUTION●
Always wash your hands after handling the battery support, terminals, and other
battery-related parts.●
Do not allow children near the 12-volt battery.■
After recharging the 12-volt battery
Have the 12-volt battery inspected at your Lexus dealer as soon as possible.
If the 12-volt battery is deteriorating, co ntinued use may cause the 12-volt battery to
emit a malodorous gas, which may be de trimental to the health of passengers.■
When replacing the 12-volt battery
 P. 6 6 9
NOTICE■
When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in
the cooling fans or belt.■
Avoiding accidental short-circuits
When connecting jumper cables, observe the following precautions: ●
Make sure each jumper cable is connected to the correct terminal.●
Do not allow the ends of the jumper cable used for the “+” terminals to come into
contact with any other parts or metal surfaces in the area, such as brackets or
unpainted metal.●
Do not allow the “+” and “-” terminals of the jumper cables to come into contact
with each other.■
Exclusive jump starting terminal precaution
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 vehi-
cle.

7885-2. Steps to take in an emergency
If your vehicle overheats
Correction procedures
■ If “ENGINE OVERHEAT” is shown on the multi-information display
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 Lexus
dealer.The following may indicate that your vehicle is overheating.
● “ENGINE OVERHEAT” is shown on the multi-information display:
The engine may be overheating.
● “HYBRID SYSTEM OVERHEAT” is sh own on the multi-information
display:
A hybrid system component such as the power control unit or an
electric motor (traction motor) may be overheating.
● Steam comes out from under the hood. STEP 1
STEP 2
STEP 3

5
When trouble arises
7895-2. Steps to take in an emergency
The coolant level is satisfactory if it
is between the “FULL” and “LOW”
lines on the reservoir.
Reservoir
“FULL” line
“LOW” line
Radiator cap
Add coolant if necessary. (
 P. 6 5 5 )
Water can be used in an emer-
gency if coolant is unavailable.
Start the hybrid system and turn the air conditioning system on to
check that the radiator cooling fans operate and to check for
coolant leaks from the radiator or hoses.
The fans operate when the air conditioning system is turned on immedi-
ately after a cold start. Confirm that the fans are operating by checking
the fan sound and air flow. If it is diff icult to check these, turn the air con-
ditioning system on and off repeatedly.
(The fans may not operate in freezing temperatures.)STEP 4
STEP 5
STEP 6