2010 Lexus IS250 cooling

396
4-3. Do-it-yourself maintenance
CAUTION
The 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
●Keep hands, clothing, and tools away from the moving fan and engine drive belt.
●Be careful not to touch the engine, radiator, exhaust manifold, etc. right after driv-
ing as they may be hot. Oil and other fluids may also be hot.
●Do not leave anything that may burn easily, such as paper or rags, in the engine
compartment.
●Do not smoke, cause sparks or expose an open flame to fuel or the battery. Fuel
and battery fumes are flammable.
●Be extremely cautious when working on the battery. It contains poisonous and
corrosive sulfuric acid.
■When working near the electric cooling fan or radiator grille
Be sure the “ENGINE START STOP” switch is OFF.
With the “ENGINE START STOP” switch in IGNITION ON mode, the electric
cooling fan may automatically start to run if the air conditioning is on and/or the
coolant temperature is high. (P. 4 0 8 )
■Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc. from getting
in the 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. Also, a backfire could cause a fire in the engine compartment.

400
4-3. Do-it-yourself maintenance
Engine compartment
IS350
Battery (P. 410)
Engine oil level dipstick
(P. 403)
Engine oil filler cap
(P. 403)
Brake fluid reservoir
(P. 4 0 8 )
Fuse boxes (P. 4 3 6 )Washer fluid tank
(P. 413)
Electric cooling fans
Condenser (P. 4 0 8 )
Radiator (P. 4 0 8 )
Engine coolant reservoir
(P. 4 0 6 )

401
4-3. Do-it-yourself maintenance
4
Maintenance and care
IS250
Battery (P. 410)
Engine oil level dipstick
(P. 403)
Engine oil filler cap
(P. 403)
Brake fluid reservoir
(P. 4 0 8 )
Fuse boxes (P. 4 3 6 )Washer fluid tank
(P. 413)
Electric cooling fans
Condenser (P. 4 0 8 )
Radiator (P. 4 0 8 )
Engine coolant reservoir
(P. 4 0 6 )

407
4-3. Do-it-yourself maintenance
4
Maintenance and care
■If the coolant level drops within a short time after replenishing
Visually check the radiator, hoses, engine coolant filler cap, radiator cap, drain cock
and water pump.
If you cannot find a leak, have your Lexus dealer pressure test the cap and check for
leaks in the cooling system.
■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. (Enabled: -31F [-35C])
Canada: “Toyota Super Long Life Coolant” is a mixture of 55% coolant and 45%
deionized water. (Enabled: -44F [-42C])
For more details about engine coolant, contact your Lexus dealer.
CAUTION
■When the engine is hot
Do not remove the radiator cap.
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing burns or other injuries.
NOTICE
■When adding engine 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 damaging parts or paint.

440
4-3. Do-it-yourself maintenance
Fuse layout and amperage ratings
■Engine compartment (type A fuse box)
FuseAmpereCircuit
1PWR HTR25 A
2TURN-HAZ15 AEmergency flashers, turn signals
3IG2 MAIN20 AIG2, IGN, GAUGE
4RAD NO.230 AAudio
5D/C C UT20 ADOME, MPX-B
6RAD NO.130 AAudio
7MPX-B10 A
Headlights, front fog lights, parking
lights, license plate lights, windshield
washer, horn, power door lock system,
power windows, power seats, electric
tilt and telescopic steering column,
meter, smart access system with push-
button start, outside rear view mirrors,
air conditioning system, multiplex
communication system
8DOME10 AInterior lights, meter
9CDS10 AElectric cooling fans

441
4-3. Do-it-yourself maintenance
4
Maintenance and care
FuseAmpereCircuit
10E/G-B60 AFR CTRL-B, ETCS, ALT-S, steering
lock system, exhaust system
11DIESEL GLW80 A
12ABS150 AVDIM
13RH J/B-B30 APower door lock system, smart access
system with push-button start
14MAIN30 AHeadlight low beams
15STARTER30 ASmart access system with push-button
start
16LH J/B-B30 APower door lock system, SECURITY
17P/I-B60 A
Multiport fuel injection system/
sequential multiport fuel injection sys-
tem
18EPS80 APower steering
19ALT150 A
LH J/B-AM, E/G-AM, GLW PLG2,
H E AT E R , FA N 1 , FA N 2 , D E F O G,
ABS2, RH J/B-AM, GLW PLG1,
LH J/B-B, RH J/B-B
20GLW PLG150 APTC heater
21RH J/B-AM80 A
OBD, STOP SW, TI&TE, FR P/SEAT
RH, RAD NO.3, ECU-IG RH,
RH-IG, FR S/HTR RH, ACC, CIG,
PWR OUTLET
22ABS230 AVDIM
23DEFOG50 ARear window defogger
24FA N 240 AElectric cooling fans
25FA N 140 AElectric cooling fans
26HEATER50 AAir conditioning system

5
When trouble arises
511
5-2. Steps to take in an emergency
CAUTION
■Battery precautions
The battery contains poisonous and corrosive acidic electrolyte, while related parts
contain lead and lead compounds. Observe the following precautions when han-
dling the battery.
●When working with the battery, always wear safety glasses and take care not to
allow any battery fluids (acid) to come into contact with skin, clothing or the vehi-
cle body.
●Do not lean over the battery.
●In the event that battery fluid comes into contact with the skin or eyes, immedi-
ately wash the affected area with water and seek medical attention.
Place a wet sponge or cloth over the affected area until medical attention can be
received.
●Always wash your hands after handling the battery support, terminals, and other
battery-related parts.
●Do not allow children near the battery.
NOTICE
■To prevent damaging the vehicle
Do not pull- or push-start the vehicle, because the three-way catalytic converter
may overheat and become a fire hazard.
■When handling jumper cables
Be careful that the jumper cables do not become tangled in the cooling fan or any
of the belts when connecting or disconnecting them.

512
5-2. Steps to take in an emergency
If your vehicle overheats
If your engine overheats:
Stop the vehicle in a safe place and turn off the automatic air
conditioning system.
Check to see if steam is coming out from under the hood.
If you see steam:
Stop the engine. Carefully lift the hood after the steam sub-
sides and then restart the engine.
If you do not see steam:
Leave the engine running and carefully lift the hood.
Remove the engine compartment cover. (P. 4 0 2 )
Check to see if the cooling fans are operating.
If the fans are operating:
Wait until the temperature of the engine (shown on the
instrument cluster) begins to fall and then stop the engine.
If the fans are not operating:
Stop the engine immediately and call your local Lexus
dealer.
After the engine has cooled
down sufficiently, check the
engine coolant level and inspect
the radiator core (radiator) for
any leaks.STEP1
STEP2
STEP3
STEP4
STEP5