TOYOTA PRIUS 2001 Service Repair Manual

F10937
GND+BS
DI±394
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
3 Check voltage of the ECU +BS 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 TOYOTA hand±held tester:
PREPARATION:
Remove the ABS ECU with connectors still connected.
CHECK:
Measure voltage between terminals +BS and GND of ABS ECU
connector.
OK:
Voltage: 10 ± 14 V
OK Check and replace brake ECU.
NG
4 Check for open circuit (to +BS) in harness and connector between brake ECU
and battery (See page IN±41).
NG Repair or replace harness or connector.
OK

F12406
LOCK
GNDB11
B10
F10936
SLA+
SLR+
SLR±
SLA±
B3
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±395
2001 PRIUS (RM778U)
5 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
6 Check brake actuator solenoid.
PREPARATION:
Disconnect the connector (B3) from the brake actuator.
CHECK:
Check continuity between each of terminals SLA+ and SLA±,
and terminals SLR+ and SLR± of brake actuator.
OK:
Continuity
HINT:
Resistance of each solenoid approx. 2.3 W at 20 °C (68 °F).
NG Replace brake actuator.
OK

DI±396
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
7 Check for short circuit in harness and connector between brake ECU and brake
actuator (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace brake ECU.

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±397
2001 PRIUS (RM778U)
DTCC1220±C1222/C1246/46Each Hydraulic Pressure Sensor Cir-
cuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1220/46
Either of the following 1. or 2. is detected:
1. When the ignition switch is ON, the condition that the
voltage of the terminal PREG in brake ECU is 0.14 V or
less or 4.85 V or more, or that of terminal VREG is 4.4 V
or less or 5.6 V or more continues for 1.2 sec. or more.
2. At a vehicle speed of 15 km/h (24 mph) or more, when
both the brake switch and hydro motor are OFF, the
voltage ratio of the terminal PREG to VREG of brake
ECU is 0.06 or less or 0.14 or more continues for 8 sec.
and this condition occurs consecutively 10 times.

Regulator (REG) pressure sensor

Regulator (REG) pressure sensor circuit

Brake actuator
C1221/46
Either of the following 1. or 2. is detected:
1. When the ignition switch is ON, the condition that the
voltage of the terminal PFR in brake ECU is 0.14 V or
less or 4.85 V or more, or that of terminal VFR is 4.4 V
or less or 5.6 V or more continues for 1.2 sec. or more.
2. At a vehicle speed of 15 km/h (24 mph) or more, when
both the brake switch and hydro motor are OFF, the
voltage ratio of the terminal PFR to VFR of brake ECU is
0.06 or less or 0.14 or more continues for 8 sec. and this
condition occurs consecutively 10 times.

Front (FR) pressure sensor

Front (FR) pressure sensor circuit

Brake actuator
C1222/46
Either of the following 1. or 2. is detected:
1. When the ignition switch is ON, the condition that the
voltage of the terminal PRR in brake ECU is 0.14 V or
less or 4.85 V or more, or that of terminal VRR is 4.4 V
or less or 5.6 V or more continues for 1.2 sec. or more.
2. At a vehicle speed of 15 km/h (24 mph) or more, when
both the brake switch and hydro motor are OFF, the
voltage ratio of the terminal PRR to VRR of brake ECU
is 0.06 or less or 0.14 or more continues for 8 sec. and
this condition occurs consecutively 10 times.

Rear (RR) pressure sensor

Rear (RR) pressure sensor circuit

Brake actuator
C1246/46
Either of the following 1. or 2. is detected:
1. When the ignition switch is ON, the condition that the
voltage of the terminal PMC in brake ECU is 0.14 V or
less or 4.85 V or more, or that of terminal VMC is 4.4 V
or less or 5.6 V or more continues for 1.2 sec. or more.
2. At a vehicle speed of 15 km/h (24 mph) or more, when
both the brake switch and hydro motor are OFF, the
voltage ratio of the terminal PMC to VMC of brake ECU
is 0.06 or less or 0.14 or more continues for 8 sec. and
this condition occurs consecutively 10 times.

Master cylinder (M/C) pressure sensor

Master cylinder (M/C) pressure sensor circuit

Brake actuator
DI296±06

F12677
(Shielded)Brake ECU
SG1 E2
22
PMC 10
12
3
24
VCM VRR B1
19
(Shielded) B WR
23
B10 (Shielded) (Shielded) B WR
B WR
B WR Brake Actuator
10 B1
B1
B1
B1
B1
B1
B1
B1
B1
B1
B1B13
B10 B10 B10 B12
B12 B12 B12 B12 B12
B12 B12 B13 B13 B13
SG2 VREG PREG EREGSG3 SG4
VFR PFR EFR PRRERR 20
13
5
27
28
9
18
25
16
15
12 6
7
11
4
8
12
5
9 DI±398
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
WIRING DIAGRAM

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±399
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
HINT:
Start the inspection from step 1 in case of using the TOYOTA hand±held tester and start from step 2 in case
of not using the TOYOTA hand±held tester.
1 Check output value of the each pressure sensor.
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 that the brake fluid pressure value of the master cylinder pressure sensor, regulator pressure sensor,
front pressure sensor and rear pressure sensor displayed on the TOYOTA hand±held tester is changing
when depressing the brake pedal.
OK:
Brake fluid pressure value must be changing.
OK Go to step 4.
NG

F12669
ON
E
2
FRR
PREG
PFR
PMC
EREGERR
EFR
DI±400
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
2 Check each pressure sensor.
PREPARATION:
(a) Install the LSPV gauge to the front caliper bleeder plug
portion, and bleed LSPV gauge.
SST 09709±29018
(b) Remove the brake ECU with connectors still connected.
CHECK:
Turn the ignition switch ON and depress the brake pedal, then
check the relation between the fluid pressure and voltage of ter-
minals of each pressure sensor shown below with the connec-
tor still connected.
Pressure sensor nameSymbols
Master cylinder pressure sensorPMC ± E2
Regulator pressure sensorPREG ± EREG
Front pressure sensorPFR ± EFR
Rear pressure sensorPRR ± ERR
OK:
Front brake caliper fluid pressureVoltage
0 kPa (0 Kgf/cm2, 0 psi)0.37 ± 0.63 V
5,883 kPa (60 kgf/cm2, 853 psi)1.57 ± 1.83 V
11,768 kPa (120 kgf/cm2, 1,706 psi)2.77 ± 3.03 V
HINT:
It should be taken into account that the difference in voltage be-
tween terminals is caused by the slightly different pressure ap-
plied to each pressure sensor.
OK Go to step 4.
NG
3 Check for open and short circuit in harness and connector between each pres-
sure sensor and brake ECU (See page IN±41).
NG Repair or replace harness or connector.
OK
Replace brake actuator.

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±401
2001 PRIUS (RM778U)
4 Check whether or not the brake ECU terminal STP input voltage is changed
when the stop light switch is turned on and off.
NO Check the stop light switch circuit (See page
BE±2).
YES
Check and replace brake ECU.

F12678
Ignition SwitchFL Block No. 1
BatteryB±Y
2 4
W±B
W±B
W±B J15
6 1
IG1
GND3
GND1 GND4 DC/DC
AM1
ECU±IG
IDJ/C
A
A AW±B
GND2
B10 F131
12
2B 1 B±G
IEBrake ECU
817 W±GW
Instrument Panel J/B31 2H 2I 2D
2KF11
FL
Block
No. 2B11 B11
B11
B10
J1
J/C J11
J/C6
68 J14
213
35
IG1
RelayB±Y
B±Y
W±BE D
MAIN DI±402
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
DTC C1241/41 IG Power Source Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1241/41
Either of the following 1. 2. or 3. is detected:
1. While a vehicle is driven at a speed of 3 km/h (5 mph),
the condition that the voltage of the terminal IG1 in brake
ECU is 9 V or less continues for 10 sec. or more.
2. When the solenoid relay is ON, the contact point of the
relay becomes OFF for 0.2 sec. or more due to the volt-
age decrease of the terminal IG1 in brake ECU.
3. When ignition switch is ON, the voltage of terminal IG1
in brake ECU remains in 17 V or more for 1.2 sec. or
more.

Battery

Charging system

Power source circuit
WIRING DIAGRAM
DI0WV±13

F12428
Instrument Panel J/B
ECU±IG
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±403
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check ECU±IG fuse.
PREPARATION:
Remove the ECU±IG fuse from instrument panel J/B.
CHECK:
Check continuity of ECU±IG fuse.
OK:
Continuity
NG Check for short circuit in all the harness and
components connected to ECU±IG fuse (See
attached wiring diagram).
OK
2 Check battery positive voltage.
OK:
Voltage: 10 ± 14 V
NG Check and repair the charging system (See
page HV±39).
OK