2001 TOYOTA PRIUS Service Repair Manual

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

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).