2001 TOYOTA PRIUS ABS

F12681
Brake ECU
B2
2 6
AA 1
1 ABS
No. 2
Engine Room J/B22
2 2
22
14
22
Y 1
3 FL
Block No. 12
2
J1
J/CL±O
5IA2
LG±R
13R1+
R2+ Y±B
W±L F12
IE2 G±W W±L
Battery 1B
6
H6 H6
B±G 1K
Hydraulic Brake
Booster7
W±BY±G14
3Y±G
MR2MR1
MTT
MT+
MT± 29
27
28
18 ABS
No. 3
FL
Block No. 2B
1K
F13H5
H6
H5
H5
H5
W±B W±B
AAY±B
B11
B13
B10
B13
B10
B10
B10
J7
J/CEngine
Room
R/B No. 2 Hydro
Motor
Relay
No. 2 Hydro
Motor
Relay
No. 1 1
23
43
4 2 1
G
MAIN
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±411
2001 PRIUS (RM778U)
DTC C1251/51 Hydraulic Brake Booster Pump Motor
Malfunction
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1251/51
Either of the following 1. or 2. is detected:
1. After turning the ignition switch ON, the current of more
than 28A flows to the motor for more than 1 sec.
2. After turning the ignition switch ON, less than 7A
change in current is detected more than 3 times in a row
when the motor is ON.
Hydraulic brake booster pump motor
WIRING DIAGRAM
DI298±06

F12681
Brake ECU
B2
2 6
AA 1
1 ABS
No. 2
Engine Room J/B22
2 2
22
14
22
Y 1
3 FL
Block No. 12
2
J1
J/CL±O
5IA2
LG±R
13R1+
R2+ Y±B
W±L F12
IE2 G±W W±L
Battery 1B
6
H6 H6
B±G 1K
Hydraulic Brake
Booster7
W±BY±G14
3Y±G
MR2MR1
MTT
MT+
MT± 29
27
28
18 ABS
No. 3
FL
Block No. 2B
1K
F13H5
H6
H5
H5
H5
W±B W±B
AAY±B
B11
B13
B10
B13
B10
B10
B10
J7
J/CEngine
Room
R/B No. 2 Hydro
Motor
Relay
No. 2 Hydro
Motor
Relay
No. 1 1
23
43
4 2 1
G
MAIN DI±414
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
DTC C1252/52 Hydraulic Brake Booster Pump Motor
ON Time Abnormally Long
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1252/52After turning the ignition switch ON, when the power is sup-
plied to the pump motor for more than 5 minutes.
Hydraulic brake booster pump motor

Hydraulic brake booster pump motor circuit

Pressure switch (PH or PL)
WIRING DIAGRAM
DI6AB±02

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±421
2001 PRIUS (RM778U)
DTC C1253/53 Hydro Motor Relay Circuit
CIRCUIT DESCRIPTION
The hydro motor relay supplies power to the hydraulic brake booster pump motor. While the ABS & EBD &
RBS are activated, the ECU switches the motor relay ON and operates the hydraulic brake booster pump
motor.
DTC No.DTC Detecting ConditionTrouble Area
C1253/53
When any of the following 1. through 4. is detected:
1. After turning the ignition switch ON, open in the relay
coil is detected for more than 1 sec.
2. When the pressure switch does not control motor
driving, the status that the motor relay is always ON
continues for more than 1 sec. due to short circuit.
3. When the pressure switch (PH) detects the low
pressure or while the pump motor operates to increase
the pressure, the status that the motor relay does not
turn ON continues for more than 0.2 sec.
4. When pressure switch does not control motor driving,
the status that the motor relay is always ON due to the
welded contact continues for more than 2 sec.

Hydro motor relay

Hydro motor relay circuit
DI29A±13

F12681
Brake ECU
B2
2 6
AA 1
1 ABS
No. 2
Engine Room J/B22
2 2
22
14
22
Y 1
3 FL
Block No. 12
2
J1
J/CL±O
5IA2
LG±R
13R1+
R2+ Y±B
W±L F12
IE2 G±W W±L
Battery 1B
6
H6 H6
B±G 1K
Hydraulic Brake
Booster7
W±BY±G14
3Y±G
MR2MR1
MTT
MT+
MT± 29
27
28
18 ABS
No. 3
FL
Block No. 2B
1K
F13H5
H6
H5
H5
H5
W±B W±B
AAY±B
B11
B13
B10
B13
B10
B10
B10
J7
J/CEngine
Room
R/B No. 2 Hydro
Motor
Relay
No. 2 Hydro
Motor
Relay
No. 1 1
23
43
4 2 1
G
MAIN DI±422
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
WIRING DIAGRAM

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±429
2001 PRIUS (RM778U)
DTC C1256/56 Accumulator Low Pressure Malfunc-
tion
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1256/56
Either of the following 1. through 5. is detected:
1. With the vehicle running, when the pressure switch (PL)
detects high pressure, although ABS, EBD or RBS
does not control, the pressure switch (PL) detects low
pressure for more than 1.4 sec.
2. With the vehicle running, when the pressure switch
(PL) detects high pressure, although ABS, EBD or RBS
controls, the pressure switch (PL) detects low pressure
for more than 0.2 sec.
3. After the ignition switch is turned ON, the pressure
switch (PL) detects low pressure for more than 60 sec.
4. After the ignition switch is ON, PL (Low pressure switch)
turns ON while PH (High pressure switch) is stuck to
ON, or PL cannot turn OFF for 1.4 sec. or more when
running the vehicle without ABS, EBD or RBS control.
5. After the ignition switch is ON, PL turns ON while PH is
stuck to ON, or PL cannot turn OFF for 0.2 sec. or more
when running the vehicle under ABS, EBD or RBS con-
trol.

Accumulator

Pressure switch (PH or PL)

Hydraulic brake booster pump motor
DI6AD±02

DI±440
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check that brake ECU connectors are securely connected to brake ECU.
NO Connect connectors to brake ECU.
YES
2 Is DTC output?
Check DTC on page DI±353.
YES Repair circuit indicated by output code.
NO
3 Is normal code displayed?
YES Check ABS solenoid relay. Check for short cir-
cuit in harness and connector between ABS so-
lenoid relay and DLC3 (See page IN±41).
NO
4 Does ABS warning light go off?
YES Check for open or short circuit in harness and
connector between ECU±IG fuse and brake ECU
(See page IN±41).
NO

F12444
ON
WA
B11
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±441
2001 PRIUS (RM778U)
5 Check battery positive voltage.
CHECK:
Check the battery positive voltage.
OK:
Voltage: 10 ± 14 V
NG Check and repair charging system (See page
HV±39).
OK
6 Check operation of the ABS warning light.
In case of using the TOYOTA hand±held tester:
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON, and push the TOYOTA hand±held tester main switch ON.
(c) Select the ACTIVE TEST mode on the TOYOTA hand±held tester.
CHECK:
Check that ºONº and ºOFFº of the ABS warning light can be shown on the combination meter by the TOYOTA
hand±held tester.
In case of not using the TOYOTA hand±held tester:
(a) Disconnect the connector (B11) from the brake ECU.
(b) Using service wire, connect terminal WA of brake ECU
harness side connector and body ground.
(c) Turn the ignition switch ON.
OK:
ABS warning light goes off.
OK Check and replace brake ECU.
NG
Check for short circuit in harness and connector between combination meter and brake ECU,
combination meter and DLC3 (See page IN±41).
Check ABS solenoid relay circuit (See page DI±376).

F12683
Brake ECU
Instrument Panel J/B GAUGE 4
IH L FL Block No. 1
1
BatteryIgnition Switch
2
2
2K2A18
W
3AM1IP1
AABS
2A14 2B F11
C10
J11
J/CB±W
5WA
W±B W±G
2H 2D DC/DC
B±Y
1
FL Block
No. 2 B±G
F131
B11
1C10
C10L2
10
22
5 1
3
6
87
LCommbination
Mater
2B 6
IDBR MAIN DI±442
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
ABS Warning Light Circuit
CIRCUIT DESCRIPTION
If the ECU detects trouble, it lights the ABS warning light while at the same time prohibiting ABS control. At
this time, the ECU records a DTC in memory.
Connect terminals Tc and CG of the DLC3 to make the ABS warning light blink and output the DTC.
WIRING DIAGRAM
DI29F±14