ECU Lexus HS250h 2012 Workshop Manual

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4-3. Do-it-yourself maintenance
HS250h_U_75050U
11ECU-IG NO.110 A
Rear view mirror, electronically con-
trolled brake system, electric power
steering system, moon roof, rain-sens-
ing windshield wiper, emergency
flashers switch, air conditioning sys-
tem, electric head restraints, driver
monitor, steering switch, seat heaters/
ventilators, electric tilt & telescopic
steering wheel, rear sunshade, AFS
12S/ROOF30 AElectric moon roof
13DOOR RL25 ARear power window (left-side)
14DOOR RR25 ARear power window (right-side)
15SHADE RR10 ARear sunshade
16D FR DOOR25 ADriver’s side power window, outside
rear view mirror
17P FR DOOR25 APassenger’s side power window, out-
side rear view mirror
18TI & TE30 AElectric tilt & telescopic steering
wheel
19STOP10 AStop lights, electronically controlled
brake system
20A/C NO.210 ANo circuit
FuseAmpereCircuit

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4-3. Do-it-yourself maintenance
4
Maintenance and care
HS250h_U_75050U
21RR FOG7. 5 ANo circuit
22FUEL OPN7. 5 ATrunk opener switch, fuel filler door
opener switch
23OBD7. 5 AOn-board diagnosis
24PWR SEAT FL30 ADriver’s side power seat
25FR FOG15 AFront fog lights
26PWR SEAT FR30 APassenger’s side power seat
27PSB30 APre-collision seat belts system
28WELCAB30 ANo circuit
29DOOR NO.125 APower door lock system
30SEAT HTR FL10 ADriver’s side seat heater
31SEAT HTR FR10 APassenger’s side seat heater
32RAD NO.27. 5 A
Navigation system, audio system, air
conditioning system, HUD, remote
touch
33PWR OUTLET15 APo w e r o u t l e t
34ECU-ACC10 ARear view mirror, air conditioning sys-
tem, audio system, navigation system
FuseAmpereCircuit

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4-3. Do-it-yourself maintenance
4
Maintenance and care
HS250h_U_75050U■
Lights other than the above
If any of the lights listed below has burnt out, have it replaced by your
Lexus dealer.
● Headlight low beams (LED headlight type)
● Side turn signal lights
● Stop/tail lights
● Tail lights
● Rear side marker lights
● High mounted stoplight
● Outer foot lights
■When replacing the front righ t headlight, front turn signal lights and parking light
bulbs
■LED light bulbs
The headlight low beams (LED headlights type), side turn signal lights, rear side
marker lights, stop/tail lights, tail lights and high mounted stoplight consist of a num-
ber of LEDs. If any of the LEDs burn out, take your vehicle to your Lexus dealer to
have the light replaced. Remove the securing clip and move the
washer fluid filler opening to allow easy
access to the light bulbs.
After replacing the bulbs, make sure to
secure the washer fluid filler opening with the
clip.

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4-3. Do-it-yourself maintenance
HS250h_U_75050U
■Condensation build-up on the inside of the lens
Contact your Lexus dealer for more information in the following situations. Tempo-
rary condensation build-up on the inside of the headlight lens does not indicate a
malfunction.
●Large drops of water have built up on the inside of the lens.
●Water has built up inside the headlight.
■When replacing light bulbs
→P. 4 8 0
CAUTION
■Replacing light bulbs
●Turn off the lights. Do not attempt to replace the bulb immediately after turning
off the lights.
The bulbs become very hot and may cause burns.
●Do not touch the glass portion of the light bulb with bare hands. Hold the bulb by
the plastic or metal portion.
If the bulb is scratched or dropped, it may blow out or crack.
●Fully install light bulbs and any parts used to secure them. Failure to do so may
result in heat damage, fire, or water entering the headlight unit. This may damage
the headlights or cause condensation to build up on the lens.
■To prevent damage or fire
Make sure bulbs are fully seated and locked.

5
When trouble arises
495
5-1. Essential information
HS250h_U_75050U
If your vehicle needs to be towed
Before towingThe following may indicate a problem with your hybrid transmission.
Contact your Lexus dealer before towing.
● The hybrid system is operating but the vehicle will not move.
● The vehicle makes an abnormal sound.
Emergency towing
If a tow truck is not available in an
emergency, your vehicle may be
temporarily towed using a cable or
chain secured to the emergency
towing eyelet(s). This should only
be attempted on hard surfaced
roads for short distances at under
18 mph (30 km/h).
A driver must be in the vehicle to
steer and operate the brakes. The
vehicle’s wheels, drive train, axles,
steering and brakes must be in
good condition.
If towing is necessary, we recommend having your vehicle towed by your
Lexus dealer or a commercial towing service, using a lift-type truck or a
flatbed truck.
Use a safety chain system for all towing, and abide by all state/provincial
and local laws.

5
When trouble arises
497
5-1. Essential information
HS250h_U_75050UTighten down the towing eyelet
securely using a wheel nut wrench.
Towing with a sling-type truck
Do not tow with a sling-type truck
to prevent body damage.
Towing with a wheel-lift type truckFrom the front Release the parking brake.

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When trouble arises
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5-1. Essential information
HS250h_U_75050U
■Before emergency towingTurn the “POWER” switch to ON mode. ( →P. 1 5 3 )
Do not turn the “POWER” switch to ACCESSORY mode.
Release the parking brake.
Change the shift position to N.
When the “POWER” switch is in ACCESSORY mode, the shift position
cannot be changed to N.
■Emergency towing eyelet location
→ P. 5 3 2
CAUTION
■Caution while towing
●Use extreme caution when towing the vehicle.
Avoid sudden starts or erratic driving maneuvers which would place excessive
stress on the emergency towing eyelets and the cables or chains. Always be cau-
tious of the surroundings and other vehicles while towing.
●Do not turn off the power switch.
This may lead to accidents as the parking lock will be engaged.
●If the hybrid system is off, the power assist for the brakes and steering will not
function, making steering and braking more difficult.
■Installing towing eyelets to the vehicle
Make sure that the towing eyelets are installed securely.
If not securely installed, the towing eyelets may come loose during towing. This may
lead to accidents that cause serious injury or even death.

5
When trouble arises
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5-2. Steps to take in an emergency
HS250h_U_75050U
■SRS warning light
This warning light system monitors the airbag sensor assembly, front airbag sensors,
side and curtain shield airbag sensors, curtain shield and rear side airbag sensors,
driver’s seat position sensor, driver’s seat belt buckle switch, front passenger occu-
pant classification system (ECU and sensors), “AIR BAG ON” indicator light, “AIR
BAG OFF” indicator light, front passenger’s seat belt buckle switch, seat belt pre-
tensioner assemblies, inflators, interconnecting wiring and power sources. (→P.
109)
■Front passenger detection sensor, passen ger seat belt reminder and warning
buzzer
●If luggage is placed on the front passenger seat, the front passenger detection
sensor may cause the warning light to flash and the warning buzzer to sound
even if a passenger is not sitting in the seat.
●If a cushion is placed on the seat, the sensor may not detect a passenger, and the
warning light may not operate properly.
■Electric power steering system warning light (warning buzzer)
When the 12-volt battery charge becomes insufficient or the voltage temporarily
drops, the electric power steering system warning light may come on and the warn-
ing buzzer may sound.
■If the malfunction indicator lamp comes on while driving
First check the following:
●Is the fuel tank empty?
If it is, fill the fuel tank immediately.
●Is the fuel tank cap loose?
If it is, tighten it securely.
The light will go off after several driving trips.
If the light does not go off even after several trips, contact your Lexus dealer as soon
as possible.
■When the tire pressure warning light comes on
Check the tire inflation pressure and adjust to the appropriate level. Pushing the tire
pressure warning reset switch will not turn off the tire pressure warning light.

5
When trouble arises
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5-2. Steps to take in an emergency
HS250h_U_75050U
Have the vehicle inspected by your Lexus dealer immediately.A buzzer sounds and a warning message is shown on the multi-informa-
tion display. Failure 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.
Wa r n i n g m e s s a g eDetails
Indicates a malfunction in the P position control A buzzer also sounds.
In this situation, there is a possibility that the parking
lock mechanism will not work.
When parking, park the vehicle on a flat surface and
apply the parking brake securely. Also, it may not be
possible to turn the “POWER” switch off. If this hap-
pens, applying the parking brake will enable the
switch to be turned off.
(Flashes)
(If equipped)
Indicates a malfunction in the LED headlight system A buzzer also sounds.
(Flashes)
(If equipped)
Indicates a malfunction in the pre-collision system A buzzer also sounds.

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5-2. Steps to take in an emergency
HS250h_U_75050U
Once
(Flashes)
• When the doors were unlocked
with the
mechanical key
and then the
“POWER”
switch was
pressed, the
electronic key
could not be
detected in the
vehicle.
• The electronic key could not be
detected in the
vehicle even
after the
“POWER”
switch was
pressed two
consecutive
times.
Touch the elec-
tronic key to the
“POWER” switch
while depressing
the brake pedal.
Once
(Flashes)
An attempt was
made to start the
hybrid system
with the shift posi-
tion in N.Change the shift
position to P and
start the hybrid
system.
Interior buzzerExterior buzzerWarning messageDetailsCorrection
procedure