2018 LEXUS RX450h overheating

82 1-3. Hybrid system
RX450h_RX450hL _U_OM48F85UNOTICE ■
Hybrid battery (traction battery) air intake/discharge vents ●
Do not place objects that will block the air intake vents. The hybr id battery (traction
battery) may overheat and be damaged. ●
Clean the air intake/discharge vents regularl y to prevent the hybrid battery (traction
battery) from overheating.●
Do not get water or foreign materials in either the air intake/discharge vents as this
may cause a short circuit and damage the hybrid battery (traction battery). ●
Do not carry large amounts of water such as water cooler bottles in the vehicle. If
water spills onto the hybrid battery (tract ion battery), the battery may be damaged.
Have the vehicle inspected by your Lexus dealer.

100 2. Instrument cluster
RX450h_RX450hL _U_OM48F85U■
Tachometer
Hybrid System Indicator switches to the tachometer when driving mode is in sport mode.
The settings of the tachometer display can be changed on of the multi-information
display. ( → P. 108)■
Engine speed
On hybrid vehicles, engine speed is precisel y controlled in order to help improve fuel
efficiency and reduce exhaust emissions etc.
There are times when the engine speed that is displayed may differ even when vehicle
operation and driving conditions are the same. ■
Brightness of the meters (d ay mode and night mode)
The brightness of the meters is changed between day mode and night mode. ●
Day mode: When the tail lights are off or when the tail lights are on but the surrounding
area is bright ●
Night mode: When the tail lights are on and the surrounding area is dark ■
Outside temperature display ●
In the following situations, the correct outside temperature may not be displayed, or the
display may take longer than normal to change:
• When stopped, or driving at low speeds (less than 12 mph [20 km/h])
• When the outside temperature has changed suddenly (at the entrance/exit of a
garage, tunnel, etc.) ●
When “ − − ” or “E” is displayed, the sy stem may be malfunctioning.
Take your vehicle to your Lexus dealer. ■
Clock settings screen (vehicles with a navigation system only)
If the clock adjustment screen is displayed continuously wh en attempting to change the
clock settings, the system may be malfunctioning.
Have the vehicle inspected by your Lexus dealer. ■
Customization
Some functions can be customized. ( → P. 108)
NOTICE ■
To prevent damage to the engine and its components●
Do not let the indicator needle of the tachometer enter the red zone, which indicates
the maximum engine speed. ●
The engine may be overheating if the engine coolant temperature gauge is in the red
zone (H). In this case, immediately stop the vehicle in a safe place, and check the
engine after it has cooled completely. ( → P. 702)

218 4-1. Before driving
RX450h_RX450hL _U_OM48F85UWARNING
Observe the following precautions.
Failure to do so may result in death or serious injury. ■
When taking a nap in the vehicle
Always turn the hybrid system off. Otherwise, if you accidentally move the shift lever or
depress the accelerator pedal, this could cause an accident or fire due to hybrid system
overheating. Additionally, if the vehicle is parked in a poorly ve ntilated area, exhaust
gases may collect and enter the vehicle, lead ing to death or a serious health hazard.■
When braking ●
When the brakes are wet, drive more cautiously.
Braking distance increases when the brakes are wet, and this may cause one side of
the vehicle to brake differently than the other side. Also, the parking brake may not
securely hold the vehicle. ●
If the electronically controlled brake function does not operate, do not follow other
vehicles closely and avoid hills or sharp turns that require braking.
In this case, braking is still possible, bu t the brake pedal should be depressed more
firmly than usual. Also, the braking distan ce will increase. Have your brakes fixed
immediately. ●
The brake system consists of 2 or more indi vidual hydraulic systems; if one of the sys-
tems fails, the other(s) will still operate. In this case, the brake pedal should be
depressed more firmly than usual and the braking distance will increase. Have your
brakes fixed immediately. ■
If the vehicle becomes stuck
Do not spin the wheels excessive ly when any of the tires is up in the air, or the vehicle is
stuck in sand, mud, etc. This may damage the driveline components or propel the vehi-
cle forward or backward, causing an accident.

232 4-1. Before driving
RX450h_RX450hL _U_OM48F85U●
To maintain engine braking efficien cy and charging system performance
when using engine braking, do no t put the transmission in D. ( → P. 246)●
Instability happens more fr equently when descending steep or long downhill
grades. Before descending, slow down and downshift. Do not make sudden
downshifts while descending st eep or long downhill grades.●
Avoid holding the brake pedal down too long or applying the brakes too fre-
quently. This could cause the brakes to overheat and result in reduced braking
efficiency. ●
Due to the added load of the trailer, yo ur vehicle’s engine may overheat on hot
days (at temperatures over 85 ° F [30 ° C]) when driving up a long or steep
grade. If the engine coolant temperat ure gauge indicates overheating, imme-
diately turn off the air conditioning (if in use), pull your vehicle off the road and
stop in a safe spot. ( → P. 702)●
Always place wheel blocks under both the vehicle’s and the trailer’s wheels
when parking. Put the transmission in P and apply the parking brake. Avoid
parking on a slope, but if unavoidable, do so only after performing the follow-
ing:
Apply the brakes and keep them applied.
Have someone place wheel blocks under both the vehicle’s and trailer’s
wheels.
When the wheel blocks are in place, release the brakes slowly until the
blocks absorb the load.
Shift into P and apply the parking brake.
Turn off the hybrid system.●
When restarting afte r parking on a slope:
With the transmission in P, start the hybrid system. Be sure to keep the
brake pedal depressed.
Shift into a forward gear. If reversing, shift into R.
If the parking brake is in manual mode, release the parking brake.
( → P. 254)
Release the brake pedal, and slowly pull or back away from the wheel
blocks. Stop and apply the brakes.
Have someone retrieve the blocks. 1
2
3
4
5
1
2
3
4
5

242 4-2. Driving procedures
RX450h_RX450hL _U_OM48F85U■
Steering lock
After turning the power switch off and openin g and closing the doors, the steering wheel
will be locked due to the steering lock func tion. Operating the power switch again auto-
matically cancels the steering lock. ■
When the steering lock cannot be released
■
Steering lock motor overheating prevention
To prevent the steering lock motor from overheating, operation of the motor may be sus-
pended if the hybrid system is turned on an d off repeatedly in a short period of time. In
this case, refrain from operating the hybrid system. Afte r about 10 seconds, the steering
lock motor will resume functioning. ■
When “Access System with Elec. Key Malf unction See Owner’s Manual” is displayed
on the multi-information display
The system may be malfunctio ning. Have the vehicle inspected by your Lexus dealer
immediately. ■
If the “READY” indicator does not come on
In the event that the “READY” indicator does not come on even after performing the
proper procedures for starting the vehicl e, contact your Lexus dealer immediately.■
If the hybrid system is malfunctioning
→ P. 79 ■
If the electronic key battery is depleted
→ P. 630 ■
Operation of the power switch ●
If the switch is not pressed shortly and firm ly, the power switch mode may not change or
the hybrid system may not start. ●
If attempting to restart the hybrid system immediately after turning the power switch off,
the hybrid system may not start in some cases. After turning the power switch off,
please wait a few seco nds before restarting the hybrid system.■
If the smart access system wi th push-button start has been deactivated by a customized
setting
→ P. 692“Steering Wheel Lock Pr ess Power Switch while
Turning Wheel” will be displayed on the multi-
information display.
Check that the shift lever is in P. Press the power
switch shortly and firmly while turning the steer-
ing wheel left and right.

254 4-2. Driving procedures
RX450h_RX450hL _U_OM48F85UThe parking brake can be set and released manually.
Sets the parking brake The parking brake indicator light and
parking brake light will turn on.
Pull and hold the parking brake switch if
an emergency occurs and it is necessary
to operate the parking brake while driv-
ing.
Releases the parking brake Operate the parking brake switch while
depressing the brake pedal. Make sure
that the parking brake indicator light
and parking brake light turn off.
If the parking brake indicator light and
parking brake lamp flashes, operate the
switch again. ( → P. 660)■
Parking the vehicle
→ P. 212 ■
Parking brake operation ●
When the power switch is not in ON mode, the parking brake cannot be released using
the parking brake switch. ●
When the power switch is not in ON mode , automatic mode (automatic brake setting
and releasing) is not available. ■
If “Parking Brake Overheated Parking Brak e Unavailable” is displayed on the multi-
information display
If the parking brake is operated repeatedly over a short period of time, the system may
restrict operation to prevent overheating. If this happens, refrain from operating the
parking brake. Normal operation wi ll return after about 1 minute.■
If “EPB Activation Stopped Incompletely” or “Parking Brake Unavailable” is displayed
on the multi-information display
Operate the parking brake switch. If the message does not disappear after operating the
switch several times, the system may be ma lfunctioning. Have th e vehicle inspected by
your Lexus dealer immediately. ■
Parking brake operation sound
When the parking brake operates, a motor so und (whirring sound) may be heard. This
does not indicate a malfunction.Manual mode U.S.A. Canada
Parking
brake light1
2

386 4-5. Using the driving support systems
RX450h_RX450hL _U_OM48F85U■
ECB operating sound
ECB operating sound may be heard in the followi ng cases, but it does not indicate that a
malfunction has occurred. ●
Operating sound heard from the engine compartment when the brake pedal is oper-
ated. ●
Motor sound of the brake system heard from the front part of the vehicle when the
driver’s door is opened. ●
Operating sound heard from the engine compartment when one or two minutes
passed after the stop of the hybrid system. ■
EPS operation sound
When the steering wheel is operated, a motor sound (whirring sound) may be heard.
This does not indicate a malfunction. ■
Automatic reactivation of TRAC, Tr ailer Sway Control and VSC systems
After turning the TRAC, Trailer Sway Contro l and VSC systems off, the systems will be
automatically re-enabled in the following situations: ●
When the power switch is turned off ●
If only the TRAC system is turned off, the TRAC will turn on when vehicle speed
increases
If both the TRAC and VSC systems are turned off, au tomatic re-enabling will not
occur when vehicle speed increases. ■
Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the system from overheating
when there is frequent steering input over an extended period of time. The steering
wheel may feel heavy as a result . Should this occur, refrain from excessive steering input
or stop the vehicle and turn the hybrid system off. The EPS system should return to nor-
mal within 10 minutes.
WARNING ■
The ABS does not operate effectively when ●
The limits of tire gripping performance have been exceeded (such as excessively
worn tires on a snow covered road). ●
The vehicle hydroplanes while driving at high speed on wet or slick roads.■
Stopping distance when the ABS is operating may exceed that of normal conditions
The ABS is not designed to shorten the vehi cle’s stopping distance . Always maintain a
safe distance from the vehicle in front of you, especially in the following situations: ●
When driving on dirt, grav el or snow-covered roads●
When driving with tire chains ●
When driving over bumps on the road ●
When driving over roads with potholes or uneven surfaces■
TRAC/VSC may not operate effectively when
Directional control an d power may not be achievable wh ile driving on slippery road
surfaces, even if the TRAC/VSC system is op erating. Drive the vehi cle carefully in con-
ditions where stability and power may be lost.

5256-2. Using the air conditioning system and defogger
RX450h_RX450hL _U_OM48F85U 6
Interior features
Heated steering wheel ∗
/seat heaters ∗
/seat ventila-
tors ∗
∗ : If equippedHeated steering wheel and seat heaters heat the side grips of the steering
wheel and seats, respectively. Seat ventilators maintain good airflow by blow-
ing air from the seats. WARNING ●
Care should be taken to prevent injury if anyone in the following categories comes in
contact with the steering wheel and seats when the heater is on:
• Babies, small children, the elderly, the sick and the ph ysically challenged
• Persons with sensitive skin
• Persons who are fatigued
• Persons who have taken alcohol or drugs that induce sleep (sleeping drugs, cold
remedies, etc.) ●
Observe the following precautions to prevent minor burns or overheating:
• Do not cover the seat with a blanket or cushion when using the seat heater.
• Do not use seat heater more than necessary.
NOTICE ●
Do not put heavy objects that have an unev en surface on the seat and do not stick
sharp objects (needles, nails, etc.) into the seat. ●
To prevent 12-volt battery discharge, do not use the functions when the hybrid system
is off.