TOYOTA PRIUS 2001 Service Repair Manual

F12405
ON
IG1
GND
F12406
LOCK
GNDB11
B10
DI±404
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
3 Check voltage of the ECU IG power source.
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 DATALIST mode on the TOYOTA hand±held tester.
CHECK:
Check the voltage condition output from the ECU displayed on the TOYOTA hand±held tester.
OK:
ºNormalº is displayed.
In case of not using the TOYOTA hand±held tester:
PREPARATION:
Remove the brake ECU with connectors still connected.
CHECK:
Turn the ignition switch ON, measure voltage between termi-
nals IG1 and GND of brake ECU connector.
OK:
Voltage: 10 ± 14 V
OK Check and replace brake ECU.
NG
4 Check continuity between terminal GND of brake ECU connector and body
ground.
PREPARATION:
Disconnect the 2 connectors (B10, B11) from the brake ECU.
CHECK:
Measure resistance between terminal GND of brake ECU har-
ness side connector and body ground.
OK:
Resistance: 1 W or less
NG Repair or replace harness or connector.
OK
Check for open circuit in harness and connector between brake ECU and battery (See page
IN±41).

F12679
Ignition Switch
2W±B
W±B 6
1IG2
GND3 GND1
GND4 AM2
W±BGND2
B10
F131 2
2B
7 1
B±GBrake ECU
17 W±R
31 2G
IJ2C
F12 MAINB11 B12
B11 B101
6
8 12
B±W
BatteryW±B
IEA
A
ID Instrument Panel J/B
J1
J/CJ11
J/C 1 95
FL Block No. 2FL Block No. 1B±W W±R
2G
IB Instrument Panel J/B
Engine Room J/B
B
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±405
2001 PRIUS (RM778U)
DTC C1242/42 IG2 Power Source Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1242/42
When the vehicle is driven at a speed of 3km/h (5 mph) or
more, an open condition in IG2 circuit in brake ECU contin-
ues for 7 sec. or more.
Battery

Charging system

Power source circuit
WIRING DIAGRAM
DI7OO±01

F10935
ON
IG2
GND
DI±406
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check battery positive voltage.
OK:
Voltage: 10 ± 14 V
NG Check and repair the charging system (See
page HV±39).
OK
2 Check voltage of the ECU IG power source.
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 DATALIST mode on the TOYOTA hand±held tester.
CHECK:
Check the voltage condition output from the ECU displayed on the TOYOTA hand±held tester.
OK:
ºNormalº is displayed.
In case of not using the TOYOTA hand±held tester:
PREPARATION:
Remove the brake ECU with connectors still connected.
CHECK:
Turn the ignition switch ON, measure voltage between termi-
nals IG2 and GND of brake ECU connector.
OK:
Voltage: 10 ± 14 V
OK Check and replace brake ECU.
NG

F12406
LOCK
GNDB11
B10
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±407
2001 PRIUS (RM778U)
3 Check continuity between terminal GND of brake ECU connector and body
ground.
PREPARATION:
Disconnect the 2 connectors (B10, B11) from the brake ECU.
CHECK:
Measure resistance between terminals GND of brake ECU har-
ness side connector and body ground.
OK:
Resistance: 1 W or less
NG Repair or replace harness or connector.
OK
Check for open circuit in harness and connector between brake ECU and battery (See page
IN±41).

F12680
Battery B±G F13 1
FL Block
No. 2 F11
1
H15
High Mounted
Stop Light 2HR±B STOP
C Instrument Panel J/B
W
2 1Stop Light Switch
G±W
5IB1 2K
2G±W
A
AJ14
J/C
G±W 9Brake ECU
STP
G±WB11
2 1
W±B9 1 2E
BI 1
BKR7
Stop Light RH
W±B W±BW±BJ30
5E
R6
Stop Light LH
G±W
J30
J31J31C
G±W
G±W W±B
C C
C
J32 J33J33J/C J/C1
FL Block
No. 1E
DC/DC
MAIN DI±408
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
DTC C1249/49 Stop Light Switch Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1249/49
When the ignition switch is ON, the condition that the termi-
nal STP in brake ECU is 3 ± 12 V continues for 1 sec. or
more.
Stop light switch

Stop light switch circuit
WIRING DIAGRAM
DI1GO±09

F12407
LOCK
STP
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±409
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check operation of the stop light switch.
CHECK:
Check that the stop light lights up when brake pedal is depressed and turns off when the brake pedal is re-
leased.
OK Go to step 3.
NG
2 Check stop light circuit (See page BE±2).
NG Repair or replace stop light circuit.
OK
3 Check voltage between terminal STP of brake ECU and body ground.
PREPARATION:
Remove the brake ECU with connectors still connected.
CHECK:
Measure voltage between terminal STP of brake ECU and body
ground when brake pedal is depressed.
OK:
Voltage: 8 ± 14 V
OK Check and replace brake ECU.
NG

DI±410
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
4 Check for open circuit in harness and connector between brake ECU and stop
light switch (See page IN±41).
NG Repair or replace harness or connector.
OK
Proceed to next circuit inspection on prob-
lem symptoms table (See page DI±365).

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

F12408
BM2
BM1
GND2 GND1
F12409
BM1
MTT MT+
MT± GND1
GND2
DI±412
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check operation of hydraulic brake booster pump motor.
PREPARATION:
Disconnect the 2 connectors from the hydraulic brake booster.
CHECK:
Connect battery positive
lead to BM1 or BM2 terminal and
battery negative  lead to GND1 or GND2 terminal of the hy-
draulic brake booster (pump motor) connector.
OK:
The operation sound of the pump motor should be
heard.
NG Go to step 4.
OK
2 Check hydraulic brake booster resistance.
CHECK:
Check resistance between terminals MT+ and MT±, BM1 and
MTT, BM2 and MTT, GND1 and MT+, GND2 and MT+ of the hy-
draulic brake booster connector.
OK:
30 ± 36 W
NG Replace the hydraulic brake booster assembly.
OK

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±413
2001 PRIUS (RM778U)
3 Check for open circuit in harness and connector between hydraulic brake boost-
er and brake ECU (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace brake ECU.
4 Check for open or short circuit in harness and connector between hydraulic
brake booster pump motor and hydraulic brake booster (See page IN±41).
NG Replace wire harness.
OK
5 Check hydraulic brake booster pump motor (See page BR±48).
NG Replace hydraulic brake booster pump motor.
OK
Replace
hydraulic brake booster.