TOYOTA PRIUS 2001 Service Repair Manual

DI±434
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
6 Check pressure switch (PH) and pressure switch (PL).
CHECK:
Compare the pressure value of the rear wheel cylinder measured in check pressure switch (PL) operation
with the one measured in check pressure switch (PH) operation.
OK:

Pressure when the voltage between PH and PHG becomes 6 to 0 V > pressure when the resis-
tance between PL and PLG becomes 5.7 kW to 1.0 kW.

Pressure when the resistance between PH and PHG becomes 0 kW to 1 kW > pressure when
the resistance between PL and PLG becomes 1.0 kW to 5.7 kW.
NG Replace hydraulic brake booster assembly.
OK
Check and replace brake ECU.
7 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
8 Check hydraulic brake booster pump motor (See page BR±48).
NG Replace hydraulic brake booster pump motor.
OK
Replace
hydraulic brake booster.

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
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±435
2001 PRIUS (RM778U)
DTC C1257/57 Power Supply Drive Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1257/57
After turning the ignition switch ON, open or short circuit in
circuit of power supply drive system inside ECU continues
for more than 1.5 sec.
Battery

Power source circuit
WIRING DIAGRAM
DI29D±07

F12428
Instrument Panel J/B
ECU±IG
DI±436
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
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

F12405
ON
IG1
GND
F12406
LOCK
GNDB11
B10
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±437
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).

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
B11 B11
B11
B10
J1
J/C J11
J/C6
68 J14
213
35
IG1
RelayB±Y
B±Y
W±BE D
FL
Block
No. 2
MAIN
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±439
2001 PRIUS (RM778U)
DTC Always ON Malfunction in ECU
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
Always ON
Either of the following 1. or 2. is detected:
1. ECU connectors are disconnected from ECU
2. There is a malfunction in ECU internal circuit
Battery

Charging system

Power source circuit

Brake ECU
HINT:
There is a case that TOYOTA hand±held tester cannot be used when ECU is abnormal.
WIRING DIAGRAM
DI7OQ±01

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

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±443
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
HINT:
Troubleshoot in accordance with the chart below for each trouble symptom.
ABS warning light does not light up*1
ABS warning light remains on*2
*1: 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 TOYOTA hand±held tester.
*2: After inspection with step 4, start the inspection from step 5 in case of using the TOYOTA hand±held
tester and start from step 6 in case of not using TOYOTA hand±held tester.
1 Check operation of the brake warning light.
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 on the TOYOTA
hand±held tester.
OK Check and replace brake ECU.
NG
2 Check ABS warning light.
See combination meter troubleshooting on page BE±2.
NG Repair bulb or combination meter assembly.
OK

F00043
1 2 3
4 5 6
1 2 3
4 5 6
1 2 3
4
65 Open
Continuity
Continuity
Continuity
Open
(+)(±)
(+) (±)1 2 3
4 5 6 Continuity
DI±444
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
3 Check ABS solenoid relay.
PREPARATION:
Remove the ABS solenoid relay from engine room R/B No. 3.
CHECK:
Check continuity between each terminal of ABS solenoid relay.
OK:
Terminals 4 and 6Continuity (Reference value 80 W)
Terminals 2 and 3Continuity
Terminals 1 and 3Open
CHECK:
(a) Apply battery positive voltage between terminals 4 and 6.
(b) Check continuity between each terminal of ABS solenoid
relay.
OK:
Terminals 2 and 3Open
Terminals 1 and 3Continuity
CHECK:
Connect the
test lead to terminal 5 and the  lead to terminal
3. Check continuity between the terminals.
OK:
Continuity
If there is no continuity, connect the  test lead to terminal 5
and the
lead to terminal 3. Recheck continuity between ter-
minals.
NG Replace ABS solenoid relay.
OK
Repair or replace and check for open circuit in harness and connector between DLC3 and ABS
solenoid relay and body ground (See page IN±41).