2004 Lexus ES330 Brake booster

STARTING AND DRIVING
288
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 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.

DRIVING TIPS
308Avoid engine over-revving. Use a gear position suitable
for the road on which you are traveling.
Avoid continuous speeding up and slowing down.
Stop-and-go driving wastes fuel.
Avoid unnecessary stopping and braking. Maintain a
steady pace. Try to time the traffic signals so you only need
to stop as little as possible or take advantage of through
streets to avoid traffic lights. Keep a proper distance from
other vehicles to avoid sudden braking. This will also
reduce wear on your brakes.
Avoid heavy traffic or traffic jams whenever possible.
Do not rest your foot on the brake pedal. This causes
premature wear, overheating and poor fuel economy.
Maintain a moderate speed on highways. The faster you
drive, the greater the fuel consumption. By reducing your
speed, you will cut down on fuel consumption.
Keep the front wheels in proper alignment. Avoid hitting
the curb and slow down on rough roads. Improper
alignment not only causes faster tire wear but also puts an
extra load on the engine, which, in turn, wastes fuel.
Keep the bottom of your vehicle free from mud etc. This
not only lessens weight but also helps prevent corrosion.Keep your vehicle tuned-up and in top shape. A dirty air
cleaner, improper valve clearance, dirty plugs, dirty oil and
grease, brakes not adjusted, etc. all lower engine
performance and contribute to poor fuel economy. For
longer life of all parts and lower operating costs, keep all
maintenance work on schedule, and if you often drive under
severe conditions, see that your vehicle receives more
frequent maintenance. (For scheduled maintenance
information, please refer to the Owner's Manual
Supplement/Scheduled Maintenanceº.)
CAUTION
Never turn off the engine to coast down hills. Your
power steering and brake booster will not function
without the engine running. Also, the emission control
system operates properly only when the engine is
running.

MAINTENANCE
347 Accelerator pedal
Check the pedal for smooth operation and uneven pedal effort
or catching.
Brake pedal
Check the pedal for smooth operation and the proper
clearance and freeplay. Check the brake booster function.
Brakes
At a safe place, check that the brakes do not pull to one side
when applied.
Parking brake
Check that the pedal has the proper travel and that, on a safe
incline, your vehicle is held securely with only the parking brake
applied.
Automatic transmission Parkº mechanism
On a safe incline, check that your vehicle is held securely with
the selector lever in Pº position and all brakes released.
Vehicle exterior
Items listed below should be performed from time to time,
unless otherwise specified.
Wheel nuts
When checking the tires, make sure to check the nuts for
looseness. Tighten them if necessary.Fluid leaks
Check underneath for leaking fuel, oil, water or other fluid after
the vehicle has been parked for a while. If you smell fuel fumes
or notice any leak, have the cause found and corrected
immediately.
Doors and engine hood
Check that all doors, including trunk lid, operate smoothly and
all latches lock securely. Make sure the engine hood
secondary latch secures the hood when the primary latch is
released.
Tire inflation pressure
Check the tire inflation pressure with a gauge every
two weeks, or at least once a month and adjust as
shown on the tire and loading information label. See
page 389 for additional information.
Tire surface
Check the tires carefully for cuts, damage or
excessive wear. See page 402 for additional
information.
Tire rotation
Rotate the tires according to the maintenance
schedule. (For scheduled maintenance information,
please refer to the Owner's Manual
Supplement/Scheduled Maintenanceº.) See page 401
for additional information.