2005 TOYOTA PRIUS brakes

10
Toyota hybrid system combines a gaso-
line engine and electric motor power to
improve the fuel economy and minimize
the emissions as well as to provide
better power performance than the ordi-
nary gasolinepowered vehicles.
Depending on the driving condition, the
vehicle runs on the best combination of;
Gasoline engine power
Electric motor power generated by
the gasoline engine
Electric motor power of the hybrid
vehicle battery
Furthermore, the energy is efficiently used
in the following ways:
When stopping the vehicle, the gaso-
line engine is automatically stopped.
When applying the brakes or decelerat-
ing, electricity is converted from the
turning force of the wheels and stored
in the hybrid vehicle battery. (This is
called regenerative brake.)
Since the battery is charged by the
gasoline engine as needed, it does not
require charging from an outside
source like an electric vehicle.
If you do not use the vehicle for a
long time (2 weeks or more), the hy-
brid vehicle battery and auxiliary battery
will discharge and their condition is li-
able to decline. Therefore, in order to
make up for discharging, charge them
once in every 2 weeks for about 30
minutes by starting the hybrid system
with all electrical components turned off.Basic operations are described below. Be-
sides, Toyota hybrid system performs vari-
ous controls depending on the operating
condition: The “Energy Monitor” screen
tells you which power is used currently.
Toyota hybrid system Toyota hybrid system
operating condition

12
12p019c
Storing electric power
When decreasing speed or applying the
brakes, the turning force of the wheels
makes the electric motor operate as a
generator and additional electricity is
stored in the hybrid vehicle battery (regen-
erative brake).
12p020c
Not in use
When stopping, the gasoline engine auto-
matically shuts off.
12p030b
Charging hybrid vehicle battery
When the hybrid vehicle battery power is
insufficient, the gasoline engine charges
the hybrid vehicle battery. The system al-
ways supplies electricity at a constant lev-
el.

11 9
(a) Brake System Warning Lights andBuzzer
These lights come on in the following
cases when the “IG −ON” mode is enabled.
RED WARNING LIGHT
When the parking brake is applied...
This light comes on when the “IG −ON”
mode is enabled, even after the parking
brake is released.
When the brake fluid level is low...
CAUTION
It is dangerous to continue driving
normally when the brake fluid level is
low.
YELLOW WARNING LIGHT
When the regenerative brake system
is fails...
RED OR YELLOW WARNING LIGHT
When the hydraulic brake system
fails...
When the yellow warning light comes on,
it is no problem to continue driving. How-
ever, if the red warning light comes on,
it indicates a serious problem and you can
continue driving no longer. Have your vehicle checked at your
Toyota dealer in the following cases:
The lights do not come on even if the
parking brake is applied when the
“READY” light is on.
The lights do not come on even if the
“POWER” switch is pressed with the
parking brake released.
A red warning light turning on briefly dur-
ing operation does not indicate a problem.
CAUTION
If any of the following conditions oc-
curs, immediately stop your vehicle at
a safe place and contact your Toyota
dealer.
The red warning light does not turn
off even after the parking brake is
released while the hybrid system is
running.
The red warning light comes on or
buzzer sounds continuously.
In either case, this can indicate that
the brakes may not work properly and
your stopping distance will become
longer. Depress the brake pedal firmly
and bring the vehicle to an immediate
stop.
The brake system warning light re-
mains on together with the “ABS”
and “VSC” warning light.
In this case, not only the antilock
brake system and vehicle stability
control system will fail but also the
vehicle will become extremely unsta-
ble during braking.
In the following case, drive directly to
the nearest Toyota dealer.
The yellow warning light comes on
while driving.

140
The vehicle stability control system
helps provide integrated control of the
systems such as antilock brake sys-
tem, brake assist system, hybrid system
control, etc. This system automatically
controls the brakes and hybrid system
to help prevent the vehicle from skid-
ding when cornering on a slippery road
surface or operating steering wheel
abruptly.
This system activates when the vehicle
speed is more than about 15 km/h (9
mph).CAUTION
Do not rely exclusively on the ve-
hicle stability control system. Even
if the vehicle stability control sys-
tem is operating, you must always
drive carefully and attentively to
avoid serious injury. Reckless driv-
ing will result in an unexpected ac-
cident. If the slip indicator light
flashes, sounding an alarm, special
care should be taken while driving.
Only use tires of specified size. The
size, manufacturer, brand and tread
pattern for all 4 tires should be the
same. If you use tires other than
specified, or mixed types or size,
the vehicle stability control system
may not function correctly. When
replacing the tires or wheels, con-
tact your Toyota dealer. (See
“Checking and replacing tires” on
page 293.)
25p115
Slip indicator light
If the vehicle is going to skid during driv-
ing, the slip indicator light blinks and an
alarm sounds intermittently. Special care
should be taken while driving.
The slip indicator light blinks in the follow-
ing conditions also.
The vehicle tires are racing. Utmost
care is required when driving.
When the anti−lock brake system is
operating. See “Brake system” on page
211 for details.
Vehicle stability control
system

211
REGENERATIVE BRAKE
When the brake is applied, the electric
motor used as a generator converts kinet-
ic energy into electric energy.
The regenerative brake works in the fol-
lowing operations.1. When the accelerator pedal is re- leased, the reduced speed equal to en-
gine braking in a gasoline −fueled ve-
hicle is obtained in accordance with the
running mode position of the shift le-
ver.
2. When the brake pedal is depressed with the shift lever in “D” or “B”, the
regenerative brake works. HYDRAULIC BRAKE
This brake system has 3 independent hy-
draulic circuits. If either circuit should fail,
the other will still work. However, the ped-
al will be harder to press, and your stop-
ping 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 ACTUATOR
The brake actuator uses brake fluid pres-
surized by the pump to power
−assist the
brakes. If the brake actuator fails during
driving, the brake system warning light
comes on and buzzer sounds continuous-
ly. In this case, the brakes may not work
properly. If they do not work well, depress
the brake pedal firmly. If the brake system
warning light comes on, immediately stop
your vehicle and contact your Toyota deal-
er. The yellow brake system warning light
may stay on for about 60 seconds after
the “IG
−ON” mode is enabled. It is normal
if the light turns off after a while.
Depressing the brake pedal repeatedly
may turn on the red brake system warning
light and buzzer. It is normal if the light
turns off and the buzzer stops sounding
after a few seconds.
You may hear a small sound in the engine
compartment after the hybrid system is
started or the brake pedal is depressed
repeatedly. This is a pump pulsating
sound of the brake system, and it is not
a malfunction.
In the following conditions, you may hear
a motor sound in the engine compartment.
The brake pedal is depressed when the
hybrid system is turned off.
The driver ’s door is opened.
For a few seconds after the hybrid
system is “OFF” and a bout 90 seconds
have passed.
The brake pedal stroke may be short
when you press the “POWER” switch with
the brake pedal depressed.
Brake system

212
CAUTION
Do not pump the brake pedal if the
hybrid system is not operating.
Each push on the pedal uses up
your reserved brake fluid pressure.
Even if the power assist is com-
pletely lost, the brakes will still
work. But you will have to push the
pedal hard, much harder than nor-
mal. And your braking distance will
increase.
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, the slip indicator in
the instrument cluster flashes and you
will 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 op-
erative 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 cov-
er, a steel plate at a construction site,
joints in a bridge, etc. on a rainy day
tends to activate the anti
−lock brake sys-
tem.
When the antilock brake system is ac-
tivated, the following condition may oc-
cur. They do not indicate a malfunction
of the system:
You may hear the anti −lock brake sys-
tem operating and the vibrations of the
vehicle body and steering wheel. You
may also hear the motor sound in the
engine compartment even after the ve-
hicle is stopped.

214
“ABS” warning light
The light comes on when the “IGON”
mode is enabled. If the antilock brake
system works properly, the light turns
off after the “READY” light comes on.
Thereafter, if the system 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 does not operate,
but the brake system still operates con-
ventionally.
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.
If either of the following conditions oc-
curs, this indicates a malfunction some-
where in the components monitored by
the warning light system. Contact your
Toyota dealer as soon as possible to
service the vehicle.
The light does not come on when the
“IG −ON” mode is enabled, or the
“READY” light remains on.
The light comes on while you are driv-
ing. A warning light turning on briefly during
operation does not indicate a problem.
CAUTION
If the “ABS” warning light remains on
together with the red brake system
warning light, immediately stop your
vehicle at a safe place and contact
your Toyota dealer.
In this case, not only the antilock
brake system will fail but also the
vehicle will become extremely unsta-
ble during braking.
Either of the following conditions may
occur, but does not indicate a malfunc-
tion:
The light may stay on for about 60
seconds after the “IG
−ON” mode is en-
abled. It is normal if it turns off after
a whi l e.
Depressing the brake pedal repeatedly
may turn on the light. It is normal if
it turns off after a few seconds. BRAKE ASSIST SYSTEM
When you slam the brakes on, the
brake assist system judges as an emer-
gency stop and provides more powerful
braking for a driver who cannot hold
down the brake pedal firmly.
When you slam the brakes on, more pow-
erful braking will be applied. At this time,
you may hear a sound in the engine
compartment. This does not indicate a
malfunction.
The brake assist system becomes opera-
tive 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 warn-
ing light, see “Service reminder indicators
and warning buzzers” on page 117.

215
The electric power steering system, us-
ing an electric motor, assists the turn-
ing of the steering wheel.
In the following cases, you may feel the
steering becomes heavy. However, the
electric power steering system warning
light does not come on. (Because it is
not a malfunction.)
When maneuvering the steering fre-
quently or keeping the steering wheel
turned fully while the vehicle is stopped
or moving very slowlyThe power steering effect will be re-
duced to prevent the system from over-
heating. Avoid turning the steering
wheel, or stop the vehicle. When you
leave the vehicle in the “IG −ON” mode
for a while, the system will become
cool.
NOTICE
If you repeat the operation which will
turn on the overheating prevention
function, the electric power steering
system may be damaged.
When the auxiliary battery is dis-
charged
Check the auxiliary battery’s condition.
If necessary, recharge or replace the
battery. For details, see “Checking aux-
iliary battery condition” on page 300.
When the steering wheel is operated
with the hybrid system not to be turned
on (with the “READY” light off)
The auxiliary battery capacity is de-
creased temporarily. The system re-
turns to normal some time after the
hybrid system is turned on.
If there is a problem somewhere in the
electric power steering system, the warn-
ing light comes on in the multi −information
display. For details, see “Multi −information
display” on page 124.30p003
The brake pad wear limit indicators on
your disc brakes give a warning noise
when the brake pads are worn to where
replacement is required.
If you hear a squealing or scraping noise
while driving, have the brake pads
checked and replaced by your Toyota
dealer as soon as possible. Expensive ro-
tor damage can result if the pads are not
replaced when necessary.
Electric power steering system Brake pad wear limit
indicators