brake Lexus HS250h 2012 Repair Manual

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4-3. Do-it-yourself maintenance
HS250h_U_75050U
Fuse layout and amperage ratingsEngine compartment
FuseAmpereCircuit
1HTR50 AAir conditioning system
2RDI40 AElectric cooling fans
3OIL PMP10 AHybrid system, transmission
4S-HORN10 ANo circuit
5ABS MAIN NO.27. 5 AElectronically controlled brake system
6H-LP CLN30 AHeadlight cleaner
7P- CO N M T R30 A
P position control system, hybrid sys-
tem, smart access system with push-
button start
8AMP NO.130 AAudio system, back door opener
9IGCT30 APCU, IGCT NO.2, IGCT NO.3,
hybrid system

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Maintenance and care
HS250h_U_75050U
10P CON MAIN7. 5 A
P position control system, hybrid sys-
tem, smart access system with push-
button start
11AM27. 5 A
Smart access system with push-button
start, hybrid system, multiport fuel
injection system/sequential multiport
fuel injection system, P position con-
trol system, cruise control system,
dynamic radar cruise control system
12ECU-B27. 5 A
Smart access system with push-button
start, multiport fuel injection system/
sequential multiport fuel injection sys-
tem, trunk opener switch
13MAYDAY10 AMAYDAY
14ECU-B310 AAir conditioning system, rear window
defogger, mirror heater
15TURN & HAZ10 ATurn signal lights, emergency flashers
16ETCS10 A
Multiport fuel injection system/
sequential multiport fuel injection sys-
tem
17ABS MAIN NO.120 AElectronically controlled brake system
18P/ I 240 A
P position control system, hybrid sys-
tem, transmission, smart access sys-
tem with push-button start, horn,
headlights (low beam), back-up lights
19ABS MTR 130 AElectronically controlled brake system
20ABS MTR 230 AElectronically controlled brake system
21H-LP HI MAIN20 AHeadlights (high beam)
22AMP NO.230 AAudio system, navigation system
FuseAmpereCircuit

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4-3. Do-it-yourself maintenance
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Maintenance and care
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3IGN10 A
Electronically controlled brake sys-
tem, multiport fuel injection system/
sequential multiport fuel injection sys-
tem, smart access system with push-
button start, stop lights
4MET7. 5 AMeters
5WIP30 AWindshield wipers
6WA S H E R15 AWindshield washer
7A/C10 AAir conditioning system
8GAUGE10 AAFS, turn signal lights, emergency
flasher lights
9AFS10 AAdaptive front-lighting system
10ECU-IG NO.210 A
Pre-collision system, LKA, dynamic
radar cruise control, air conditioning
system, outside rear view mirror,
HUD, navigation system, tire inflation
pressure warning system
FuseAmpereCircuit

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4-3. Do-it-yourself maintenance
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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

5
When trouble arises
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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.

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When trouble arises
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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
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■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.

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When trouble arises
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5-1. Essential information
HS250h_U_75050U
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
● High engine coolant temperature warning light flashes or comes
on
■ 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, spongy feeling, pedal almost touches
the floor

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5-2. Steps to take in an emergency
If a warning light turns on or a warning buzzer sounds...
Stop the vehicle immediately. Continuing to drive the vehicle may be dangerous.
The following warning indicates a possible problem in the brake system.
Immediately stop the vehicle in a safe place and contact your Lexus
dealer.
*: Brake system warning buzzer
When there is a possible problem that could affect braking performance, the
warning light will come on and a warning buzzer will sound.
Parking brake engaged warning buzzer
→ P. 5 1 6
Stop the vehicl e immediately.
The following warning indicates the possibility of damage to the vehicle
that may lead to an accident. Immediately stop the vehicle in a safe place
and contact your Lexus dealer.
Warning lightWarning light/Details
(U.S.A.)

(Canada)
Brake system warning li ght and warning buzzer*
•Low brake fluid
• Malfunction in the brake system This light also comes on when the parking brake is not
released. If the light turns off after the parking brake is fully
released the system is operating normally.
Warning lightWarning light/Details
Charging system warning light
Indicates a malfunction in the vehicle’s charging system
Calmly perform the following actions if any of the warning lights comes on
or flashes. If a light comes on or flashes, but then goes off, this does not nec-
essarily indicate a malfunction in the system. However, if this continues to
occur, have the vehicle inspected by your Lexus dealer.

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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.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