2012 Lexus HS250h engine overheat

146
2-1. Driving procedures
HS250h_U_75050U
CAUTION
●Do not shift the shift position to D while the vehicle is moving backward.
Doing so can damage the transmission and may result in a loss of vehicle control.
●Moving the shift position to N while the vehicle is moving will disengage the
hybrid system. Engine braking is not available with the hybrid system disengaged.
●During normal driving, do not turn off the hybrid system. Turning the hybrid sys-
tem off while driving will not cause loss of steering or braking control, but the
power assist to these systems will be lost. This will make it more difficult to steer
and brake, so you should pull over and stop the vehicle as soon as it is safe to do
so.
However, in the event of an emergency, such as if it becomes impossible to stop
the vehicle in the normal way: →P. 5 5 8
●Use engine braking (shift position B) to maintain a safe speed when driving down
a steep hill.
Using the brakes continuously may cause the brakes to overheat and lose effec-
tiveness. ( →P. 160)
●Do not adjust the positions of the steering wheel, the seat, or the inside or outside
rear view mirrors while driving.
Doing so may result in a loss of vehicle control that can cause accidents, resulting
in death or serious injury.
●Always check that all passengers' arms, heads or other parts of their body are not
outside the vehicle, as this may result in death or serious injury.
●Do not drive in excess of the speed limit. Even if the legal speed limit permits it, do
not drive over 85 mph (140 km/h) unless your vehicle has high-speed capability
tires. Driving over 85 mph (140 km/h) may result in tire failure, loss of control and
possible injury. Be sure to consult a tire dealer to determine whether the tires on
your vehicle are high-speed capability tires or not before driving at such speeds.
■When driving on slippery road surfaces
●Sudden braking, acceleration and steering may cause tire slippage and reduce
your ability to control the vehicle, resulting in an accident.
●Abrupt changes from shift position D to B and rapid changes in the engine speed
could cause the vehicle to skid, resulting in an accident.

147
2-1. Driving procedures
2
When driving
HS250h_U_75050U
CAUTION
●After driving through a puddle, lightly depress the brake pedal to make sure that
the brakes are functioning properly. Wet brake pads may prevent the brakes from
functioning properly. If the brakes on only one side are wet and not functioning
properly, steering control may be affected, resulting in an accident.
■When changing the shift position
Be careful not to change the shift position with the accelerator pedal depressed.
Changing the shift position to any positions other than P or N may cause the vehicle
to accelerate abruptly, causing an accident and resulting in death or serious injury.
After changing the shift position, make sure to confirm the current shift position dis-
played on the shift position indicator inside the meter.
■If you hear a squealing or scraping noise (brake pad wear limit indicators)
Have your Lexus dealer check and replace the brake pads as soon as possible.
Rotor damage may result if the pads are not replaced when needed.
It is dangerous to drive the vehicle when the wear limits of the brake pads and/or
those of the brake discs are exceeded.
■When the vehicle is stopped
●Do not depress the accelerator pedal unnecessarily.
If the vehicle is in any shift position other than P or N, the vehicle may accelerate
suddenly and unexpectedly, causing an accident.
●Do not leave the vehicle with the hybrid system on for a long time.
If such a situation cannot be avoided, park the vehicle in an open space and
check that exhaust fumes do not enter the vehicle interior.
●In order to prevent accidents due to the vehicle rolling away, always keep
depressing the brake pedal while the “READY” indicator is on. Apply the parking
brake as necessary.
●If the vehicle is stopped on an incline, in order to prevent accidents caused by the
vehicle rolling forward or backward, always depress the brake pedal and securely
apply the parking brake as needed.
●Avoid revving or racing the engine.
Running the engine at high speed while the vehicle is stopped may cause the
exhaust system to overheat, which could result in a fire if combustible material is
nearby.

172
2-2. Instrument cluster
HS250h_U_75050U
NOTICE
■To prevent damage to the hybrid system and its components
A high engine coolant temperature warning light (→P. 502) is installed instead of
an engine coolant temperature gauge. If the high engine coolant temperature
warning light illuminates or flashes, the vehicle may be overheating. Immediately
stop the vehicle in a safe area ( →P. 5 5 2 ) .

5
When trouble arises
503
5-2. Steps to take in an emergency
HS250h_U_75050U
Have the vehicle inspected by your Lexus dealer 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.
High engine coolant temperatur e warning light (flashes or
comes on)
Indicates that the engine is overheating →P. 552
• Flashes: Engine is overheating. Drive carefully.
• Comes on: Engine is overheated. Stop the vehicle.
Warning lightWarning light/Details
Brake system warning light Indicates a malfunction in:
• The regenerative brake system; or
• The electronically controlled brake system
(U.S.A.)

(Canada)
Malfunction indicator lampIndicates a malfunction in:
• The hybrid system;
• The electronic engine control system;
• The electronic throttle control system; or
• The hybrid transmission 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 lightIndicates a malfunction in:
•The ABS; or
• The brake assist system
Warning lightWarning light/Details

552
5-2. Steps to take in an emergency
HS250h_U_75050U
If your vehicle overheats
Correction procedures■ If the engine coolant temperature warning light comes on or flashes
Stop the vehicle in a safe place and turn off the air conditioning
system.
Check to see if steam is coming out from the engine area.
If you see steam:
Stop the hybrid system. Carefully lift the hood after the steam
subsides and then restart the hybrid system.
If you do not see steam:
Leave the hybrid system operating and carefully lift the hood.
Check to see if the cooling fans are operating.
If the fans are operating:
Wait until the high engine coolant temperature warning light goes
off and then stop the hybrid system.
If the fans are not operating:
Stop the hybrid system immediat ely and call your Lexus dealer.
The following may indicate that your vehicle is overheating:
●The high engine coolant temperature warning light comes on or
flashes:
The engine may be overheating.
● “HYBRID SYSTEM OVERHEAT” is shown on the multi-information
display:
The power control unit may be overheating.
Follow the correction procedure as described below.

5
When trouble arises
553
5-2. Steps to take in an emergency
HS250h_U_75050UAfter the hybrid system has cooled
down sufficiently, check the engine
coolant level and inspect the cool-
ing system for leaks.
If the engine compartment cover
needs to be removed. (
→P. 4 3 8 )
Add engine coolant if necessary.
Water can be used in an emer-
gency if engine coolant is unavail-
able. ( →P. 5 6 4 )
Have the vehicle inspected at the nearest Lexus dealer as soon as possi-
ble.
■If “HYBRID SYSTEM OVERHEAT” is shown on the multi-informa-
tion display
Stop the vehicle in a safe place.
Stop the hybrid system (press the “POWER” switch once), and
then carefully lift the hood.
Wait until the hybrid system has
fully cooled down. When the sys-
tem has fully cooled down, check if
coolant has leaked from the radia-
tor core.
If a large amount of coolant leak-
age is found, contact your Lexus
dealer immediately.

554
5-2. Steps to take in an emergency
HS250h_U_75050UCheck that the coolant level of the
power control unit is between the
“FULL” and “LOW” lines of the
reservoir tank.
“FULL” line
“LOW” line
If the coolant level of the power
control unit is insufficient, add
more coolant.
If power control unit coolant is
unavailable, water can be used as
an emergency substitute.
Restart the hybrid system (depress and hold the brake pedal, and
press the “POWER” switch once). Check that the “HYBRID
SYSTEM OVERHEAT” message has gone off.
If the warning message remains on, stop the hybrid system and
contact your Lexus dealer.
Have the vehicle inspected at the nearest Lexus dealer as soon as possi-
ble.
■Overheating
The following symptoms may occur when your vehicle is overheating:
●The high engine coolant temperature warning light comes on or flashes, or the
hybrid system output decreases.
●Steam comes out from the engine area.
●“HYBRID SYSTEM OVERHEAT” is displayed on the multi-information display.

616
Alphabetical index
HS250h_U_75050U
Cooling systemEngine overheating .......................... 552
Cruise control Cruise control ....................................... 212
Dynamic radar crui se control ....... 216
Cup holders ............................................. 381
Curtain shield airbags.......................... 109
Customizable features ...................... 584
Daytime running light system ........... 194
Defogger* Rear window.........................................274
Side mirrors ...........................................274
Dimensions............................................. 560
Dinghy towing ........................................ 262
Display
Dynamic radar cruise control.................................................... 216
Multi-information display................. 177
Trip information ................................... 180
Warning message............................... 512
Do-it-yourself maintenance .............. 431
Door courtesy lights Door courtesy lights......................... 374
Wattage................................................. 568
Doors
Door glasses ........................................... 90
Door lock.................................. 47, 58, 61
Rear door child protector ................ 62
Side doors .................................................. 61
Side mirrors ............................................. 87
Driver’s seat belt reminder light .... 505
Driver’s seat position memory ........... 72
Driving
Break-in tips ........................................... 143
Correct posture ................................... 107 Procedures............................................. 142
Winter driving tips ............................ 258
Driving position memory.......................72
Electric power steering...................... 238
Electronic key If the electronic key does not operate properly............................ 544
Emergency, in case of If the electronic key does not
operate properly............................ 544
If the engine will not start ................. 541
If the hybrid system will not start ......................................................... 541
If the 12-volt battery is discharged .........................................547
If the warning buzzer sounds...... 502
If the warning light turns on.......... 502
If the warning message is displayed .............................................. 512
If you have a flat tire ........................ 532
If you lose your keys ........................ 543
If you think something is wrong ....................................................501
If your electronic key does not operate properly ................... 544
If your vehicle becomes stuck .... 556
If your vehicle has to be stopped in an emergency ............................558
If your vehicle needs to be
towed ................................................... 495
If your vehicle overheats................ 552
Emergency flasher Switch ...................................................... 494
Engine Accessory mode ................................. 153
D
E