2005 LEXUS LS430 ABS

STARTING AND DRIVING
367
Antilock brake system
The antilock brake system is designed to automatically
help prevent lockup of the wheels during a sudden
braking or braking on slippery road surfaces. This assists
in providing directional stability and steering
performance of the vehicle under these circumstances.
Effective way to press the ABS brake pedal: When the
anti−lock brake system function is in action, you may feel the
brake pedal pulsating and hear a noise. In this situation, to
let the anti−lock brake system work for you, just hold the
brake pedal down more firmly. Do not pump the brake in a
panic stop. This will result in reduced braking performance.
The anti −lock brake system becomes operative after the
vehicle has accelerated to a speed in excess of approximately
10 km/h (6 mph). It stops operating when the vehicle
decelerates to a speed below approximately 5 km/h (3 mph).
Depressing the brake pedal on slippery road surfaces such as
on a manhole cover, a steel plate at a construction site, joints
in a bridge, etc. on a rainy day tends to activate the anti −lock
brake system.
You may hear a click or motor sound in the engine
compartment for a few seconds when the engine is started or
just after the vehicle begins to move. This means that the
anti−lock brake system is in the self− check mode, and does not
indicate a malfunction. When the antilock brake system is activated, the
following conditions may occur. They do not indicate a
malfunction of the system:

You may hear the anti− lock brake system operating and feel
the brake pedal pulsating and the vibrations of the vehicle
body and steering wheel. You may also hear the motor
sound in the engine compartment even after the vehicle is
stopped.
 At the end of the anti−lock brake system activation, the
brake pedal may move a little forward.
CAUTION
Do not overestimate the antilock brake system:
Although the antilock brake system assists in
providing vehicle control, it is still important to drive
with all due care and maintain a moderate speed and
safe distance from the vehicle in front of you, because
there are limits to the vehicle stability and effectiveness
of steering wheel operation even with the antilock
brake system on.
If tire grip performance exceeds its capability, or if
hydroplaning occurs during high speed driving in the
rain, the antilock brake system does not provide
vehicle control.

STARTING AND DRIVING
368
Antilock brake system is not designed to shorten the
stopping distance: Always drive at a moderate speed
and maintain a safe distance from the vehicle in front of
you. Compared with vehicles without an antilock
brake system, your vehicle may require a longer
stopping distance in the following cases:
Driving on rough, gravel or snowcovered roads.
 Driving with tire chains installed.
 Driving over the steps such as the joints on the road.
 Driving on roads where the road surface is pitted or
has other differences in surface height.
Install all 4 tires of specified size at appropriate
pressure: The antilock brake system detects vehicle
speeds u sing the speed sensors for respective wheels’
turning speeds. The use of tires other than specified
may fail to detect the accurate turning speed resulting
in a longer stopping distance.“ABS” warning light
31L350
 1 U.S.A. 2Canada
The light comes on when the ignition switch is turned to the
“ON” position. If the anti−lock brake system and the brake
assist system work properly, the light turns off after a few
seconds. Thereafter, if either of the systems malfunctions, the
light comes on again.
When the “ABS” warning light is on (and the brake system
warning light is off), the anti −lock brake system, the brake
assist system, the traction control system and/or the vehicle
stability control system do/does not operate, but the brake
system still operates conventionally.
When the “ABS” warning light is on (and the brake system
warning light is off), the anti− lock brake system does not
operate so that the wheels could lock up during a sudden
braking or braking on slippery road surfaces.

STARTING AND DRIVING
369
If any of the following conditions occurs, this indicates a
malfunction
somewhere in the components monitored by
the warning light system. Contact your Lexus dealer as
soon as possible to service the vehicle.
 The light does not come on when the ignition switch is
turned to the “ON” position, or remains on.
 The light comes on while you are driving.
A warning light turning on briefly during operation does not
indicate a problem.
CAUTION
If the “ABS” warning light remains on together with the
brake system warning light, immediately stop your
vehicle at a safe place and contact your Lexus dealer.
In this case, not only the antilock brake system will fail
but also the vehicle will become extremely unstable
during braking.
Drumindisc type parking brake system
Your vehicle has a drum−in−disc type parking brake system.
This type of brake system needs bedding −down of the brake
shoes periodically or whenever the parking brake shoes
and/or drums are replaced.
Have your Lexus dealer perform the bedding −down.
Brake assist system
If you slam the brakes on such as in an emergency or
apply the brakes more firmly than usual such as when
descending the hill with the designated number of
occupants in the vehicle, the brake assist system
provides more powerful braking.
If you slam the brakes on or apply the brakes more firmly, more
powerful braking will be applied. At this time, you may hear a
sound in the engine compartment and feel the vibrations of the
brake pedal. This does not indicate a malfunction.
The brake assist system becomes operative after the vehicle
has accelerated to a speed in excess of approximately 10 km/h
(6 mph). It stops operating when the vehicle decelerates to a
speed below approximately 5 km/h (3 mph).
For an explanation of this system’s warning light, see “ABS”
warning light on page 87 or 368.

STARTING AND DRIVING
376
Precollision brake assist system
When the precollision sensor detects an object or
vehicle with which your vehicle might collide, and
determines that a collision may be unavoidable,
depressing the brake pedal provides more powerful
braking according to the amount of pedal depression.
The pre−collision brake assist system will operate in the
following conditions:
 When the ignition switch is turned on.
 When the approaching speed in regard to the object or the
vehicle exceeds about 30 km/h (18 mph).
 When the brake pedal is depressed.
If the brake pedal is kept depressed before the sensor’s
determination of unavoidable collision, the pre −collision brake
assist system will operate soon after the sensor’s
determination.
Electronically modulated air suspension
control
When the precollision sensor detects an object or
vehicle with which your vehicle may collide, and
determines that a collision may be unavoidable, the
electronically modulated air suspension adjusts the
damping effect on the shock absorbers and regulates the
vehicle not to pitch forward so much.
The electronically modulated air suspension will operate in the
following conditions:
 When the ignition switch is turned on.
 When the vehicle speed is about 5 km/h (3 mph) or over.
 When the approaching speed in regard to the object or the
vehicle exceeds about 30 km/h (18 mph).

DRIVING TIPS
391

Because of the added load of the trailer, your vehicle’s
engine may overheat on hot days (at temperatures over
30 C [85 F]) when going up a long or steep grade with a
trailer. If the engine coolant temperature gauge indicates
overheating, immediately turn off the air conditioning (if in
use), pull your vehicle off the road and stop in a safe spot.
See “If your vehicle overheats” on page 404.
 Always place wheel blocks under both the vehicle and trailer
wheels when parking. Apply the parking brake firmly. Put
the transmission in “P”. Avoid parking on a slope with a
trailer, but if it cannot be avoided, do so only after performing
the following:
1. Apply the brakes and keep them applied.
2. Have someone place wheel blocks under both the vehicle
and trailer wheels.
3. When the wheel blocks are in place, release your brakes
slowly until the blocks absorb the load.
4. Apply the parking brake firmly.
5. Shift into “P” and turn off the engine. When restarting out after parking on a slope:
1. With the transmission in “P” position, start the engine. Be
sure to keep the brake pedal depressed.
2. Shift into the “3” (third range), “2” (second range), “\
1” (first
range) or “R” position.
3. Release the
parking brake and brake pedal and slowly pull
or back away from the wheel blocks. Stop and apply your
brakes.
4. Have someone retrieve the blocks.
CAUTION
 Do not exceed 72 km/h (45 mph) or the posted towing
speed limit, whichever is lower. Because instability
(swaying) of a towing vehicletrailer combination
usually increases as the speed increases, exceeding
72 km/h (45 mph) may cause loss of control.
 Slow down and downshift before descending steep
or long downhill grades. Do not make sudden
downshifts.
 Avoid holding the brake pedal down too long or too
frequently. This could cause the brakes to overheat
and result in reduced braking efficiency.

CHASSIS
466
CHECKING BRAKE FLUID
63L023a
To check the fluid level, simply look at the seethrough
reservoir. The level should be between the “MAX” and
“MIN” lines on the tank.
It is normal for the brake fluid level to go down slightly as the
brake pads wear. So be sure to keep the reservoir filled.
If the reservoir needs frequent refilling, it may indicate a
serious mechanical problem.
If the level is low, add FMVSS No.116 DOT 3 or SAE J1703
brake fluid to the brake reservoir.
Remove and replace the reservoir cap by hand. Add brake
fluid up to the “MAX” line.
Use only newly opened brake fluid. Once opened, brake fluid
absorbs moisture from the air, and excess moisture can cause
a dangerous loss of braking efficiency.
CAUTION
Take care when filling the reservoir because brake fluid
can harm your hands or eyes. If fluid gets on your hands
or in your eyes, flush the affected area with clean water
immediately. If you still feel uncomfortable with your
hands or eyes, go to the doctor.
NOTICE
If you spill some of the fluid, be sure to wipe it off to
prevent it from damaging the parts or paintwork.

ELECTRICAL COMPONENTS
493
No.FUSEAMPERECIRCUIT
9 PWR
OUTLET15Power outlet
10 DCIG15Rear cigarette lighter
11 OBD7.5On− board diagnosis system
12 AM17.5Starting system
13 ABSIG7.5Vehicle stability control system
14 D B/ANC5Seat belts
15 SECURITY7.5Theft deterrent system
16 A/C7.5Air conditioning system
17 STOP5Stop lights
18 D RRIG10Refreshing seat
19 IG230SRS airbag system, Engine
immobilizer system, Steering
lock system, Starting system
20 HAZ15Emergency flashers
21 STR LOCK7.5Steering lock system
22 AM27.5All components in “STA” and
“IG2”, Starting system
23 MPXB17.5
Power door lock system,
Engine immobilizer system,
Steering lock system, Front
power seat, Rear power seat
24 MPXB37.5
Tilt and telescopic steering,
Headlight switch, Windshield
wiper and washer switch, Turn
signal switch
No.FUSEAMPERECIRCUIT
25 DOME10
Vanity lights, Outer foot lights,
Ignition switch light, Clock,
Gauges and meters, Interior
lights, Personal lights
26 MPXB27.5Gauges and meters, Vehicle
stability control system,
Illuminated entry system, TEL
27 P RRIG10Refreshing seat
28 HLP LVL7.5Headlight leveling system,
Adaptive Front Lighting System
(AFS)
29 PIG7.5Rain sensor, Air conditioning
system, Moon roof,
Multi −information display, Clock
30 P S/HTR15Seat heater, Climate control
seat system
31 PACC7.5
Air conditioning system, Audio
system, Clock,
Multi −information display,
Illuminated entry system
32 PCIG15Front cigarette lighter
33 RADIO
NO.17.5Audio system
34 RR DOOR LH20Power door lock system, Power
window, Door closer system,
Door courtesy lights

ELECTRICAL COMPONENTS
494
No.FUSEAMPERECIRCUIT
35 P DOOR25
Power door lock system, Power
rear view mirror control system,
Outside rear view mirror
defogger, Door closer system,
Door courtesy lights, Power
windows
36 TEL7.5Audio system, Navigation
system
37 P B/ANC5Seat belts, Seat belt buckle
illumination
38 RR DOORRH20Power door lock system, Power
window, Door closer system,
Door courtesy lights
39 D DOOR25
Power door lock system, Door
closer system, Power rear view
mirror control system, Outside
rear view mirror defogger, Door
courtesy lights, Power windows
40 RR IG7.5
Lexus park assist system,
Electronically modulated air
suspension system, Theft
deterrent system, TEL
41 RR ACC7.5Audio system, TEL
42 RR ECUB7.5Rear air conditioning system,
Theft deterrent system, Trunk
light, Refreshing rear seat
43 RR A/C7.5Rear air conditioning system,
Air purifier
44 RR S/HTR30Seat heater, Climate control
seat system
No.FUSEAMPERECIRCUIT
45 RR
S/SHADE15Sunshade
46 LCE LP7.5License plate lights
47 S/ROOF30Moon roof
48 FUEL OPN10Fuel opener system, Trunk lid
closer system
49 AMP30Audio system
50 P P/SEAT30Power seat system
51 RR SEAT LH30Power seat system
52 RR SEATRH30Power seat system
53 LUG J/B50
All components in “RR SEAT
RH”, “RR SEAT LH”, “S/ROOF”,
“AMP”, “RR IG”, “RR ECU −B”,
“P P/SEAT”, “RR S/HTR”, “RR
S/SHADE”, “RR A/C”, “RR
ACC”, “FUEL OPN” and “LCE
LP”, Tail lights and Stop lights
54 ABS 250Vehicle stability control system
55 HEATER50Air conditioning system
56 ABS 130Vehicle stability control system
57 DEFOG40Rear window defogger
58 AIR SUS40Electronically modulated air
suspension system