brake fluid TOYOTA PRIUS 2001 Service Repair Manual

2001 PRIUS (EWD414U)
B HOW TO USE THIS MANUAL
The ground points circuit diagram shows the connections from all major parts to the respective ground points. When
troubleshooting a faulty ground point, checking the system circuits which use a common ground may help you identify
the problem ground quickly. The relationship between ground points (
EA, IB and IC shown below) can also be
checked this way.

I GROUND POINT
FAN MAIN RELAY
FAN MAIN RELAY
A/C FAN RELAY NO.2
A/C FAN RELAY NO.3
RADIATOR FAN MOTOR
RETRACT CONTROL
RELAY
RETRACT MOTOR RH
RETRACT MOTOR LH
FRONT TURN SIGNAL
LIGHT RH
PARKING LIGHT RH
FRONT TURN SIGNAL
LIGHT LH
PARKING LIGHT LH
DOOR LOCK CONTROL
SW RH
DOOR KEY LOCK
SW RH
DOOR LOCK MOTOR
RH
BLOWER RESISTOR
A/C AMPLIFIER
RADIO AND PLAYER
HEATER RELAY
AUTO ANTENNA
MOTOR
BLOWER SW
PARKING BRAKE SW
COMBINATION METER
HORN SW [COMB. SW]
TURN SIGNAL FLASHER
DOOR KEY LOCK SW LH
DOOR LOCK MOTOR LH
FUEL CONTROL SW
WOOFER AMPLIFIER
COMBINATION METER
COMBINATION METER
FUEL SENDER
CIGARETTE LIGHTER
O/D MAIN SW
CLOCK
5
5
5
5
4
4
4
4
4BA15
IB18
EA2 10
3E5
3E
6 3G
13 3F
3 3D
1 3B
7
ID115
IC33
IA12
E 3
A
A AW±B
W±BW±B W±B
W±B W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±BW±B W±B W±B W±B
W±B W±B
W±BW±B
W±B
W±B
W±B W±B
W±B
BR
W±B
BR BRW±BW±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B W±B
W±B
W±B
W±B
W±B
BR W±B
BR BR
BR W±B W±BW±B
W±BW±BBR W±B (4A±GZE)
W±B A A A
I 6
I 6
I 2
I 2
I 2
B 5I 5
I 5
I 5
B 5
B 5
B 5
I 5
I 5
I 3I 3
E 3
E 3
E 3
E 2
E 4
E 5
E 4
E 5
E 6E 4
E 4
B 4
EAI 4
B 4
B 4
I 4I 8
IBIC
3C7
4
JUNCTION
CONNECTOR J 1
4
DOOR LOCK CONTROL
RELAY
ELECTRICAL IDLE-UP
CUT RELAY (M/T)FRONT SIDE MARKER
LIGHT RH
FRONT SIDE MARKER
LIGHT LH
BRAKE FLUID LEVEL
WARNING SW
UNLOCK WARNING
SW WIPER AND WASHER
SW [COMB. SW] LIGHT CONTROL SW
[COMB. SW] HEATER CONTROL
ASSEMBLY
HEATER SERVO
MOTOR AMPLIFIER
DIMMER SW
[COMB. SW]
CRUISE CONTROL
MIRROR SW
REAR WINDOW
DEFOGGER SW
POWER WINDOW
MASTER SW
POWER WINDOW
CONTROL RELAY
DOOR LOCK CONTROL
SW
REMOTE CONTROL
MIRROR SW
*The system shown here is an EXAMPLE ONLY. It is different to the actual circuit shown in the SYSTEM CIRCUITS SECTION.

2001 PRIUS (EWD414U)
G ELECTRICAL WIRING ROUTING
Position of Parts in Engine Compartment
A 1 A/C Condenser Fan Motor
A 2 A/C Magnetic Clutch and Lock Sensor
A 3 A/C Triple Pressure SW
(A/C Dual and Single Pressure SW)
A 4 ABS Speed Sensor Front LH
A 5 ABS Speed Sensor Front RH
A 6 Ambient Temp. Sensor
B 1 Brake Actuator
B 2 Brake Actuator
B 3 Brake Actuator
B 4 Brake Fluid Level Warning SW
C 1 Camshaft Position Sensor
C 2 Camshaft Timing Oil Control Valve
C 3 Circuit Breaker Sensor
C 4 Converter
C 5 Converter
C 6 Crankshaft Position Sensor
D 1 DC Motor
E 1 Engine Coolant Temp. Sensor
E 2 Engine Hood Courtesy SWF 1 Front Airbag Sensor LH
F 2 Front Airbag Sensor RH
F 3 Front Parking Light LH
F 4 Front Parking Light RH
F 5 Front Side Marker Light LH
F 6 Front Side Marker Light RH
F 7 Front Turn Signal Light LH
F 8 Front Turn Signal Light RH
F 9 Front Wiper Motor
F 10 Fusible Link Block No.1
F 11 Fusible Link Block No.1
F 12 Fusible Link Block No.1
F 13 Fusible Link Block No.1
H 1 Headlight LH
H 2 Headlight RH
H 3 Heated Oxygen Sensor (Bank 1 Sensor1)
H 4 Horn
H 5 Hydraulic Booster
H 6 Hydraulic Booster

2001 PRIUS (EWD414U)
ABS
B 8B17
ID 1 2C 7C 8C7
16 D D7A 12 A8
16 C C25A 4
24 C C15 C18 A 11 A7
9C C28A 3
27 C
1 2 A 16 A15
1 2 14 A A13
2 1 19 B B20
P
V
B
W
R
(
SHIELDED) (
SHIELDED)
(
SHIELDED)
B
W
R
(
SHIELDED) LG±R
W± B
W± B
R
G
P
L
P
L W± B
W± B
W± B
ASG3 EFR PFR VFR SG2 EREG PREG VREG SLR± SLR+
LBL GND3 GND4 FL+ FL± FR± RL+ RL±
A 24
IB1 2 IB1 1 IB1 5 BRAKE ACTUATORB B 1 , B 2A
BRAKE ECUB B10 , B11
A
ABS SPEED SENSOR
FRONT LH A 4
ABS SPEED SENSOR
FRONT RH A 5
ABS SPEED SENSOR
REAR LH A23
JUNCTION
CONNECTOR J11
BRAKE FLUID LEVEL
WAR NI NG SW B 4
C , B 3
A 12 A 9A5
10 A A22A 1
23 A
(
SHIELDED)
B
W
R
(
SHIELDED)
SG1 E2 PMC VCM
C , B12
D , B13
FSS FR+
I 1
BR (
SHIELDED)
(
SHIELDED)
(
SHIELDED)
(
SHIELDED) P
L

2001 PRIUS (EWD414U)
1. INPUT SIGNALS
(1) Speed sensor signal
The speed of the wheels is detected and input to TERMINALS FL+, FR+, RL+ and RR+ of the brake ECU.
(2) Stop light SW signal
A signal is input to TERMINAL STP of the brake ECU when the brake pedal is depressed.
2. ABS SYSTEM OPERATION
During sudden braking the brake ECU has signals input from each sensor, which controls the current to the solenoid inside
the actuator and lets the hydraulic pressure acting on each wheel cylinder escape to the reservoir. The pump inside the
actuator is also operating at this time and it returns the brake fluid from the reservoir to the master cylinder, thus preventing
locking of the vehicle wheels.
If the brake ECU judges that the hydraulic pressure acting on the wheel cylinder is insufficient, the current on the solenoid is
controlled and the hydraulic pressure is increased. Holding of the hydraulic pressure is also controlled by the brake ECU, by
the same method as above. Pressure reduction, holding and increase are repeated to maintain vehicle stability and to
improve steerability during sudden braking.
A4, A5 ABS SPEED SENSOR FRONT LH, RH
2±1 :1.4±1.8 kW (20°C, 68°F)
A23, A24 ABS SPEED SENSOR REAR LH, RH
2±1 :1.04±1.3 kW (20°C, 68°F)
B10 (A), B11 (B), B12 (C), B13 (D) BRAKE ECU
(B) 6, (C) 1±GROUND : Approx. 12 volts with the ignition SW at ON position
(D) 22±GROUND : Always approx. 12 volts
(A) 6, (A)31±GROUND : Always continuity
: PARTS LOCATION
CodeSee PageCodeSee PageCodeSee Page
A434C10A36J1037
A534C11B36J1137
A736D236J1237
A2338E636J14A37
A2438E1036J15B37
B1A34F12C34J1637
B2B34F13D34J1737
B3C34F1838J18A37
B434G137J19B37
B8A36H5A34J2237
B10A36H6B34J2637
B11B36H1538P237
B12C36I1537S337
B13D36J137
B1436J737
: RELAY BLOCKS
CodeSee PageRelay Blocks (Relay Block Location)
223Engine Room R/B No.2 (Right Side of Reserve Tank)
324Engine Room R/B No.3 (Engine Compartment Right)
SYSTEM OUTLINE
SERVICE HINTS

2001 PRIUS (EWD414U)
I GROUND POINT
IGCT RELAY
A/C TRIPLE
PRESSURE SW
HYDRAULIC BOOSTER
WATER PUMP MOTOR
(
A/C)
FRONT PARKING
LIGHT LH
FRONT PARKING
LIGHT RHIG2 RELAY
ENGINE HOOD
COURTESY SW
FRONT WI PER MOTOR
FRONT TURN
SIGNAL LIGHT LH
RADIATOR FAN MOTOR
ABS SOL
RELAY
INVERTER
(
GND1)
(
GND2)
PTC HEATER
BLOWER MOTOR
LINEAR CONTROLLER
(
E1)
(
SG)
(
E01)
(
E02) FRONT SIDE MARKER
LIGHT LH
FRONT SIDE MARKER
LIGHT RH
FRONT TURN
SIGNAL LIGHT RH
BRAKE FLUID LEVEL
WARNING SW
WATER TEMP. SW
DRL RELAY
IGNITION COIL AND
IGNITER NO. 1
IGNITION COIL AND
IGNITER NO. 2
IGNITION COIL AND
IGNITER NO. 3
IGNITION COIL AND
IGNITER NO. 4
ENGINE CONTROL
MODULE1K3
E 5
E 5
E 5
E 5 E 5
E 5
E 5
E 5 (
±S)
E 5
E 5
3HYDRAULIC BOOSTER E 5 E 5 (
CUT±)
E 1
E 1
E 1
E 1
E 1
E 1
3W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W±B
W± BW±B
W±B W±B W±B
W±B
W±B
W±B
W±B
W±B
W±B W±B W±B W± B W±B W± B W±B W±B W±B W±B
W±B W±B W±B W±B W±B
A
AA
(
*1)IE ECW± B
W± B
W± B
W± B
W± B
W± B W±BA
AA
A
AJUNCTION
CONNECTOR J 7
J 1
JUNCTION
CONNECTOR
W±B
A
BRAKE ECU
EAE 3 E 3 E 3
EBID214
IO114 A A
B A JUNCTION
CONNECTORB J 8 , J 9A W±B
W±B
W±B
W±B
W±B
W±BBR
BR
W±B
W±BBR BR
W±B W±B W±B
BR
ENGINE CONTROL
MODULE
ENGINE CONTROL
MODULE
(
ME01)
(
E03)DATA LINK
CONNECTOR 3 HTR RELAY
NAVIGATION ECU
RADIO AND PLAYER
IFIJ121
BR
BR
BR BR
MULTI DISPLAY (
*2)(
*2)
AIRBAG SENSOR
ASSEMBLY
COMBINATION
METER(
E1)
(
ES)
IH W±B
2B6 7
LBR
2A WATER PUMP
MOTOR (
INVERTER)
2W±B
FAN NO. 2
RELAY
AEFI RELAY

L PART NUMBER OF CONNECTORS
Code Part Name Part NumberCodePart Name Part Number
Note : Not all of the above part numbers of the connector are established for the supply.
2001 PRIUS (EWD414U) A 1
A/C Condenser Fan Motor90980±11237
A 2A/C Magnetic Clutch and Lock Sensor90980±10942
A 3A/C Triple Pressure SW (A/C Dual and
Single Pressure SW)90980±10943
A 4ABS Speed Sensor Front LH90980±11003A 5ABS Speed Sensor Front RH90980±11003
A 6Ambient Temp. Sensor90980±11070
A 7A/C Amplifier90980±11911
A 8A/C Amplifier90980±11913
A 9A/C Amplifier90980±11927
A10A/C Room Temp. Sensor
A11A/C Solar Sensor90980±11919
A12A/C Thermistor
A13Accel Position Sensor90980±11144
A14Air Inlet Control Servo Motor90980±11921
A15Air Mix Control Servo Motor90980±11909A16Air Vent Mode Control Servo Motor90980±11909
A17Airbag Sensor Assembly90980±11869
A18Airbag Sensor Assembly90980±11872
A19Airbag Sensor Assembly90980±11867
A20Airbag Squib (Front Passenger Airbag
Assembly)90980±11884
A21Airbag Squib (Steering Wheel Pad)90980±10850
A22Ashtray Illumination90980±12111
A23ABS Speed Sensor Rear LH90980±11060A24ABS Speed Sensor Rear RH90980±11060
B 1Brake Actuator90980±11087
B 2Brake Actuator90980±11161
B 3Brake Actuator90980±11698
B 4Brake Fluid Level Warning SW90980±11207
B 5Back±Up Light Relay82660±20340
B 6Blower Motor90980±10214
B 7Blower Motor Linear Controller90980±11676
B 8Body ECU90980±11971
B 9Body ECU90980±11973
B10Brake ECU90980±11935
B11Brake ECU90980±11476
B12Brake ECU90980±11637
B13Brake ECU90980±11638
B14Brake Warning Buzzer90980±10906
B15Battery Blower Motor82824±47130
B16Battery Blower Motor Controller90980±11676
B17Battery ECU90980±11392
B18Battery ECU90980±11424
B19Battery Fan Relay82660±20340
B20Buckle SW and Tension Reducer LH
B21Buckle SW RH and Seat Belt Warning
Occupant Detection Sensor90980±11471
C 1Camshaft Position Sensor90980±10947
C 2Camshaft Timing Oil Control Valve90980±11162
C 3Circuit Breaker Sensor90980±11898
C 4Converter90980±10942
C 5Converter90980±11963
C 6Crankshaft Position Sensor90980±12028
C 7Center Cluster SW90980±10801
C 8Cigarette Lighter90980±10760
C 9Cigarette Lighter Illumination90980±11148
C10Combination Meter90980±11927
C11Combination Meter90980±11923
C12Combination SW90980±11594
C13Combination SW90980±11672
C14Combination SW90980±11616
D 1DC Motor90980±10838
D 2Data Link Connector 390980±11665
D 3Daytime Running Light Relay90980±12034
D 4Diode (Door Courtesy)90980±11251
D 5Diode (Daytime Running Light)90980±10962
D 6Door Courtesy SW Front LH
D 7Door Courtesy SW Front RH90980±10871D 8Door Courtesy SW Rear LH90980±10871
D 9Door Courtesy SW Rear RH
D10Door Lock Control SW Front RH90980±10797
D11Door Lock Motor and Door Unlock
Detection SW Rear LH
90980±11150
D12Door Lock Motor and Door Unlock
Detection SW Rear RH90980±11 150
D13Door Lock Motor, Door Key Lock and
Unlock SW and Door Unlock Detection SW
Front LH
90980±11858
D14Door Lock Motor, Door Key Lock and
Unlock SW and Door Unlock Detection SW
Front RH90980±11 858
E 1Engine Coolant Temp. Sensor90980±10737
E 2Engine Hood Courtesy SW90980±11189
E 3EMPS ECU90980±12012
E 4EMPS ECU90980±11579
E 5EMPS ECU90980±12120
E 6EMPS ECU90980±11923
E 7Engine Control Module90980±11421
E 8Engine Control Module90980±11476
E 9Engine Control Module90980±11637

CHASSIS ± BRAKES
182CH44
Front
Brake ActuatorRear
Hydraulic
Brake
Differential
Gear
Stroke
Simulator
Hydraulic
Adjustment Area
ABS Function AreaHydraulic
Brake
MG2
MG1Inverter
EngineHV Battery
THS (TOYOTA Hybrid System) Regenerative
Brake
Switching
Valve
Power Splitting
Device
182CH45
Combination Meter
Brake ECU
Brake Warning Buzzer
Rear Wheel
Speed Sensors
and Rotors
Hydraulic Brake Booster
(Master Cylinder Portion)
Front Wheel Speed
Sensor and Rotor
Brake Actuator HV ECU
Hydraulic Brake
Booster
Power Supply
portion
Solenoid RelayReservoir
Tank
ECMPump
Motor Relays 104
BRAKE SYSTEM
1. General

A brake system, which uses brake fluid that is stored under high pressure to assist the brake pedal effort
and to operate the ABS with EBD control and the regenerative brake cooperative control, has been adopted.

A regenerative brake system, which uses the MG2 that is used for driving the vehicle as a generator to effi-
ciently convert the energy that is created during braking, has been adopted. This system enables to collect
more driving energy by having the control to cooperate the hydraulic brake and the regenerative brake.
2. System Diagram
3. Layout of Main Components

CHASSIS ± BRAKES105
4. Function of Main Components
ComponentsFunction
ABS Warning
LightLights up to alert the driver when the brake ECU detects the
malfunction in the ABS.
Combination
Meter
Brake System

Lights up together with the ABS warning light to alert the driver
when the brake ECU detects the malfunction not only in the ABS
but also in the EBD controlBrake System
Warning Lightbut also in the EBD control.

Lights up to alert the driver when the malfunction occurs in the
brake system.
Stop Light SwitchDetects the brake depressing signal.
Brake Warning BuzzerEmits a continuous sound to inform the driver that the ABS ECU
detects the malfunction in the hydraulic brake booster.
Speed SensorsDetect the wheel speed of each of the four wheels.
Brake ECU

Processes various sensor signals, regenerative brake signals, to
execute control of the ABS control, EBD control, regenerative
coordination control and hydraulic brake booster.

Communicates control data with the HV ECU.
HV ECUMaintains serial communication with the brake ECU to exchange
regenerative coordination control signals.
Hydraulic Brake Booster
Assists with the pedal effort applied to the brake pedal.

Supplies hydraulic pressure.
Brake ActuatorControls the brake fluid pressure to each brake wheel cylinder by
signals from the brake ECU.
Solenoid RelaySupplies power to the ABS's solenoid valve's in the brake actuator.
Pump Motor RelaysControl the pump motor operation in the hydraulic brake booster.

CHASSIS ± BRAKES107
6. Construction and Operation
The brake system of Prius consists of the following components:
Components
Function
Pump and Pump Motor
Draws up the brake fluid from the reservoir tank
and provides high hydraulic pressure to the
accumulator.
Accumulator
Stores the hydraulic pressure that was generated
by the pump. The accumulator is filled with
highpressure nitrogen gas.
Power
Supply
PortionPressure Switches
Monitors the hydraulic pressure of the
accumulator and outputs control signals for the
pump motor.
There are two types: the pressure switch PH for
controlling the pump, and the pressure switch PL
for giving a warning when the pressure is low.
Hydraulic
Brake
Booster
Relief Valve
Returns the brake fluid to the reservoir tank to
prevent excessive pressure if the pump operates
continuously due to a malfunction of the pressure
switch.
Reservoir TankStores the brake fluid.
Brake Fluid Level
Warning SwitchDetects the low brake fluid level.
Master
Master Cylinder
Generates the hydraulic pressure in accordance
with the pedal effort that is applied to the brake
pedal.
Master
Cylinder
Portion
Brake Booster
Regulates the accumulator pressure in accordance
with the pedal effort that is applied to the brake
pedal and introduces this pressure to the boosterBrake Boosterpedal and introduces this pressure to the booster
chamber in order to provide a power assist to the
brakes.
Pressure SensorsDetects the pressure of the master cylinder,
regulator, and front and rear wheel cylinders.
Switching
Solenoid ValvesSwitches the hydraulic path between normal
braking and braking under control.
Brake
Actuator
ABS Control Solenoid
Valves
Pressure Holding
Valves
Pressure Reduction
Valves
Controls the hydraulic pressure that is applied to
the wheel cylinders during ABS control or EBD
control.
Actuator
Linear Solenoid Valve
Regulates the hydraulic pressure to the wheel
cylinders during braking in accordance with the
fluctuations in the regenerative brake force.
Reservoir
Temporarily stores the brake fluid when
regulating the hydraulic pressure to the wheel
cylinders in accordance with the fluctuations in
the regenerative brake force.
Stroke SimulatorGenerates a pedal stroke during braking in
accordance with the driver's pedal effort.

CHASSIS ± BRAKES
152CH17 182CH47
Reservoir Tank
Accumulator
Check
Valve
Pump and
Pump Motor To Master
Cylinder and
Solenoid
Valves
Pressure
Switch
PL
Relief
Valve
Pressure
Switch
PH
Brake ECUPump Motor
Relays
Brake Warning
BuzzerBrake System
Warning LightAccumulator
Pressure
Pressure
Switch PH
Pressure
Switch PLON
OFF
OFF
Time
Pump
Motor
Relief
ValveOpen
CloseBrake System
Warning Light
and Brake
Warning Buzzer
ON
OFF
ON
OFF
108
Hydraulic Brake Booster
1) General
Due to installation space constraints, a type of hydraulic brake booster that comprises two separate por-
tions has been adopted: the power supply portion (pump, pump motor, accumulator, pressure switches,
and relief valve) and the master cylinder portion.
Consisting of an pump and pump motor, accumulator, and hydraulic pressure switches, the hydraulic
brake booster performs the functions of both the booster and the master cylinder.
By optimizing the hydraulic circuits, the hydraulic pressure that is generated by the booster is applied
directly to the rear brakes. Thus, the hydraulic pressure from the master cylinder is used exclusively by
the front brakes.
2) Pump and Pump Motor, Accumulator, Pressure Switches and Relief Valve
If the accumulator pressure becomes lower than the pressure that is specified in the pressure switch PH,
which is used for detecting high pressure, the pressure switch PH turns OFF. Then, the brake ECU turns
ON the pump motor relays to operate the pump motor and the pump.
The brake fluid that is discharged by the pump passes through the check valve and is stored in the accumu-
lator. The hydraulic pressure that is stored in the accumulator is used for providing the hydraulic pressure
that is needed for normal braking, for operating the ABS, and for operating the EBD control, and for re-
generative brake cooperative controlling.
If the accumulator pressure becomes higher than the pressure that is specified in the pressure switch PH,
the pressure switch PH turns ON. Then, after several seconds, the brake ECU turns OFF the pump.
At this time, if the pressure switch PH malfunctions and causes the pump to operate continuously, the
relief valve opens to prevent excessive pressure from being generated.
Moreover, if the accumulator pressure becomes lower than the pressure that is specified in the pressure
switch PL, which is used for detecting low pressure, the pressure switch PL turns OFF. As a result, the
brake system warning light turns ON and the brake warning buzzer activates.
At this time, the ABS or EBD is prohibited from operating.