2005 Lexus IS300 ABS

STARTING AND DRIVING
261
BRAKE SYSTEM
The tandem master cylinder brake system is a hydraulic
system with two separate sub±systems. If either sub±system
should fail, the other will still work. However, the pedal will be
harder to press, and your stopping distance will increase. Also,
the brake system warning light may come on.
CAUTION
Do not drive your vehicle with only a single brake
system. Have your brakes fixed immediately.
Brake booster
The brake booster uses engine vacuum to power±assist the
brakes. If the engine should quit while you are driving, you can
bring the vehicle to a stop with normal pedal pressure. There
is enough reserved vacuum for one or two stops but no more!
CAUTION
Do not pump the brake pedal if the engine stalls. Each
push on the pedal uses up your reserved vacuum.
 Even if the power assist is completely lost, the brakes
will still work. But you will have to push the pedal
hard, much harder than normal. And your braking
distance will increase.
Anti±lock brake system
The anti±lock brake system is designed to automatically
help prevent lock±up 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 anti±lock brake system is activated, the
following conditions may occur. They do not indicate a
malfunction of the system:
04 06.30

STARTING AND DRIVING
263
ªABSº warning light
SV31014

U.S.A.
SV31031

CANADA
The light comes on when the ignition key is turned to the ªONº
position. If the anti±lock brake system and the brake assist
work properly, the light turns off after a few seconds.
Thereafter, if either of the systems malfunctions, the light
comes on again.
When the ªABSº 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 not operate, but the brake system
still operates conventionally.
When the ªABSº warning light is on (and the brake system
warning light is off), the anti±lock brake system and/or the
traction
control system do/does not operate so that the wheels
could lock up during a sudden braking or braking on slippery
road surfaces.
If either 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 key is turned
to the ªONº 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.
04 06.30

STARTING AND DRIVING
264
CAUTION
If the ªABSº 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 anti±lock brake system will fail
but also the vehicle will become extremely unstable
during braking.
Drum±in±disc 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
When you slam the brakes on, the brake assist system
judges as an emergency stop and provides more powerful
braking for a driver who cannot hold down the brake pedal
firmly.
When you slam the brakes on, 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 ªABSº
warning light on page 54 or 263.
04 06.30

CHASSIS
349
CHECKING BRAKE FLUID
SV63001
To check the fluid level, simply look at the see±through
reservoir. The level should be between the ªMAXº and
ªMINº lines on the tank.
It is normal for the brake fluid level to go down slightly as the
brake pads wear or when the fluid level in the accumulator is
high.
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.
Refilling brake fluid:
1. Turn the ignition switch off.
2. Depress the brake pedal more than 40 times.
3. Remove the reservoir cap by hand. Add brake fluid up to the
ªMAXº line. If you do not follow the procedure above, the reservoir may
overflow.
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.
04 06.30

ELECTRICAL COMPONENTS
379
No.FUSEAMPERECIRCUIT
26 MPX±B10
Power window system,
Air conditioning,
Gauges and meters,
Theft deterrent system
27 P RR P/W20Power window system
28 SRS±B7.5SRS system, Door lock system
29 TV7.5Television
30 OBD7.5On±board diagnosis system
31 IGN7.5
SRS system,
Multiport fuel injection
system/sequential multiport fuel
injection system,
Cruise control system
32 ECU±B120
Theft deterrent system,
Door lock system,
Interior light, Trunk light,
Vanity light, Ignition switch light,
Map light, Door courtesy lights,
Power window system,
Air conditioning,
Gauges and meters
33 ALT±S7.5Charging system
34 ETCS15Electronic throttle control
system
35 AM220
Starting system, SRS system,
Multiport fuel injection
system/sequential multiport fuel
injection system, Cruise control
system
36 HORN10Horn
No.FUSEAMPERECIRCUIT
37 RADIONO.120Audio system
38 TURN±HAZ15Turn signal lights
39 EFI25
Multiport fuel injection
system/sequential multiport fuel
injection system,
Emission control system,
Engine immobilizer system
40 DRL NO.230Daytime running light system
41 DRL NO.17.5Daytime running light system
42 H±LP L LW R15Left±hand headlight
(low beam), Fog lights
43 H±LP R LW R15Right±hand headlight
(low beam)
44 ABS27.5Anti±lock brake system
45 SPARESpare fuse
46 SPARESpare fuse
47 SPARESpare fuse
48 H±LP LUPR10Left±hand headlight
(high beam)
49 H±LP R UPR10
Right±hand headlight
(high beam),
Service reminder indicators and
buzzers
04 06.30