engine LEXUS RX450h 2015 Repair Manual

7325-1. Essential information
If you think something is wrong If you notice any of the following symptoms, your vehicle probably needs
adjustment or repair. Contact your Lexus dealer as soon as possible.
■ Visible symptoms
● Fluid leaks under the vehicle.
(Water dripping from the air conditioning after use is normal.)
● Flat-looking tires or uneven tire wear
● Engine coolant temper ature gauge needle continually points
higher than normal.
■ Audible symptoms
● 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
■ Operational symptoms
● Engine missing, stumbling or running rough
● 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, sp ongy feeling, pedal almost touches
the floor

7345-2. Steps to take in an emergency
Have the vehicle inspected immediately.
Failing to investigate the cause of the following warnings may lead to the
system operating abnormally and possibly cause an accident. Have the
vehicle inspected by your Lexus dealer immediately. Warning light Warning light/Details
(U.S.A.)
(Canada) Malfunction indicator lamp
Indicates a malfunction in:
• The hybrid system;
• The electronic engine control system;
• The electronic throttle control system; or
• The emission control system
SRS warning light
Indicates a malfunction in:
• The SRS airbag system;
• The front passenger occupant classification system; or
• The seat belt pretensioner system
(U.S.A.)

(Canada) ABS warning light
Indicates a malfunction in:
•The ABS; or
• The brake assist system
Brake system warning light
Indicates a malfunction in:
• The regenerative brake system; or
• The electronically controlled brake system
Electric power steering system warning light (warning
buzzer)
Indicates a malfunction in the EPS (Electric Power Steering)
system

7445-2. Steps to take in an emergency
Stop the vehicle immediately.
A buzzer sounds and a warning message is shown on the multi-informa-
tion display. The following warning indicates the possibility of damage to
the vehicle that may lead to an acci dent. Immediately stop the vehicle in a
safe place and contact your Lexus dealer. Wa r n i n g m e s s a g e Details
(U.S.A.)
(Canada) Indicates abnormal engine oil pressure
The warning light may come on if the engine oil pres-
sure is too low.
Indicates a malfunction in the hybrid system

7525-2. Steps to take in an emergency
(Flashes)
(If equipped) Indicates that there is a
high possibility of a fron-
tal collision, or that the
pre-collision braking
function is operating
A buzzer also sounds.
At the same time,
will appear on
the head-up display (the
image flashes). Slow the vehicle by apply-
ing the brakes.
(Flashes)
(If equipped) Indicates that your vehi-
cle is nearing the vehicle
ahead (in radar cruise
mode)
A buzzer also sounds.
At the same time,
will appear on
the head-up display (the
image flashes). Slow the vehicle by apply-
ing the brakes.
Indicates that the engine
has overheated
A buzzer also sounds. Stop and check.
(  P. 7 8 8 )Wa r n i n g m e s s a g e Details Correction procedure

5
When trouble arises
7755-2. Steps to take in an emergency
CAUTION■
When using the compact spare tire ●
Remember that the compact spare tire prov ided is specifically designed for use
with your vehicle. Do not use your compact spare tire on another vehicle.●
Do not use more than one compact spare tire simultaneously.●
Replace the compact spare tire with a standard tire as soon as possible.●
Avoid sudden acceleration, abrupt steeri ng, sudden braking and shifting opera-
tions that cause sudden engine braking.■
When the compact spare tire is attached
The vehicle speed may not be correctly detected, and the following systems may
not operate correctly: ●
ABS & Brake assist●
VSC●
TRAC●
VDIM●
Intuitive parking assist (if equipped)●
Navigation system (if equipped)●
Cruise control (if equipped)●
Dynamic radar cruise control (if equipped)●
Pre-Collision System (if equipped)
Also, not only can the following system not be utilized fully, but it may even nega-
tively affect the drive-train components: ●
AWD system (if equipped)■
Speed limit when using the compact spare tire
Do not drive at speeds in excess of 50 mph (80 km/h) when a compact spare tire is
installed on the vehicle.
The compact spare tire is not designed for driving at high speeds. Failure to observe
this precaution may lead to an accident causing death or serious injury.

7845-2. Steps to take in an emergency
If the vehicle 12-volt battery is discharged The following procedures may be used to start the hybrid system if the vehi-
cle’s 12-volt battery is discharged.
You can also call your Lexus dealer or a qualified repair shop.
If you have a set of jumper (or booster) cables and a second vehicle
with a 12-volt battery, you can jump start your vehicle by following the
steps below.
Open the hood and remove the engine compartment covers.
(  P. 655)
Remove the fuse box cover and open the exclusive jump start-
ing terminal cover.
Connect the jumper cables according to the following procedure:
Connect a positive jumper cable clam p to the exclusive jump start-
ing terminal on your vehicle
Connect a positive jumper cable cl amp to the positive (+) battery
terminal on the second vehicle
Connect a negative cable clamp to the negative (-) battery terminal
on the second vehicle
Connect the clamp at the other end of the negative cable to a solid,
stationary, unpainted metallic point away from the exclusive jump
starting terminal and any moving part s, as shown in the illustration.STEP 1
STEP 2
STEP 3

5
When trouble arises
7855-2. Steps to take in an emergency
■
Starting the hybrid system when the 12-volt battery is discharged
The hybrid system cannot be started by push-starting.■
To prevent 12-volt battery discharge ●
Turn off the headlights and the audio sy stem while the hybrid system is off.●
Turn off any unnecessary electrical compon ents when the vehicle is running at a
low speed for an extended period, such as in heavy traffic.■
When the 12-volt battery is removed or discharged ●
The power back door must be initialized.
(  P. 8 3 7 )●
The hybrid system may not start. (
 P. 6 6 8 )
●
Make sure that the key is not inside th e vehicle when recharging or replacing
the 12-volt battery. The key may be locked in the vehicle if the alarm is activated.
(  P. 1 2 8 ) Start the engine of the second vehicle. Increase the engine
speed slightly and maintain that level for approximately 5 min-
utes to recharge the 12-volt battery of your vehicle.
Open and close any of the doors of your vehicle with the
“POWER” switch off.
Maintain the engine sp eed of the second ve hicle and start the
hybrid system of your vehicle by turning the “POWER” switch
to ON mode.
Make sure the “READY” indicat or comes on. If the indicator
does not come on, contact your Lexus dealer.
Once the hybrid system has st arted, remove the jumper cables
in the exact reverse order from which they were connected.
Once the hybrid system starts, have the vehicle inspected at your
Lexus dealer as soon as possible. STEP 4
STEP 5
STEP 6
STEP 7
STEP 8

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
7915-2. Steps to take in an emergency
Add coolant if necessary. Water can be used in an emer-
gency if coolant is unavailable.
Start the hybrid system and check for the multi-information dis-
play.
If the message does not disappear:
Stop the hybrid system and contact your Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the nearest Lexus dealer.STEP 5
CAUTION■
To prevent an accident or injury when in specting under the hood of your vehicle●
If steam is seen coming from under the hood, do not open the hood until the
steam has subsided. The engine compartm ent may be very hot, causing serious
injuries such as burns.●
After the hybrid system has been turned off, check that the indicator on the
“POWER” switch and the “READY” indicator are off.
When the hybrid system is operating, the gasoline engine may automatically
start, or the cooling fans may suddenly operate even if the gasoline engine stops.
Do not touch or approach rotating parts such as the fans, which may lead to fin-
gers or clothing (especially a tie, a scarf or a muffler) getting caught, resulting in
serious injury.●
Do not loosen the radiator cap while the hybrid system and radiator are hot.
Serious injuries, such as burns, may re sult from hot coolant and steam released
under pressure. STEP 6

7925-2. Steps to take in an emergency
NOTICE■
When adding engine/power control unit coolant
Wait until the hybrid system has cooled down before adding engine/power control
unit coolant.
When adding coolant, do so slowly. 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 precautions: ●
Avoid contaminating the coolant with foreig n matter (such as sand or dust etc.).●
Do not use any coolant additives.