2001 TOYOTA PRIUS light

ECU
Power source* Hydraulic brake booster Motor relay circuit Accumulator malfunction
Pump motor circuit Pressure switchPH
PL
Pump motor
MTT wire harness
MT+ wire harness
MT± wire harness
MR1 open circuit
MR2 open circuit
MR1 welded contact
MR2 welded contact
Pressure leaks
IG2 open circuit
Power suplly circuit
Light Buzzer Light Light Light Light Light LightBuzzer Buzzer Buzzer Buzzer Buzzer Buzzer
DTC
BRAKE warning light and buzzerC1242/42
C1251/51 C1252/52 C1253/53C1254/54
C1256/56C1257/57
*: When IG1 circuit is open, ABS warning light and BRAKE warning light come on.




  
   






± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±365
2001 PRIUS (RM778U)
Table of Trouble Part and DTC:

DI1GG±06
F02094
B13 B12
B11 B10
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±367
2001 PRIUS (RM778U)
TERMINALS OF ECU
Symbols (Terminals No.)Wiring ColorConditionSTD Voltage (V)
SFRH (B10 ± 1) ± GND (B10 ±
6, 31, B11 ± 8, 17)R±B e W±BIG switch ON, ABS warning light OFF10 ± 14
SFRR (B10 ± 2) ± GND (B10 ±
6, 31, B11 ± 8, 17)R±W e W±BIG switch ON, ABS warning light OFF10 ± 14
SMC2 (B10 ± 3) ± GND (B10 ±
6, 31, B11 ± 8, 17)G±B e W±BIG switch ON, ABS warning light OFF (Brake pedal released)10 ± 14
SMC1 (B10 ± 4) ± GND (B10 ±
6, 31, B11 ± 8, 17)G±W e W±BIG switch ON, ABS warning light OFF (Brake pedal released)10 ± 14
SS (B10 ± 5) ± GND (B10 ± 6,
31, B11 ± 8, 17)G±O e W±BIG switch ON, ABS warning light OFF (Brake pedal released)10 ± 14
SFLR (B10 ± 7) ± GND (B10 ±
6, 31, B11 ± 8, 17)R±G e W±BIG switch ON, ABS warning light OFF10 ± 14
SRRH (B10 ± 8) ± GND (B10 ±
6, 31, B11 ± 8, 17)R±Ye W±BIG switch ON, ABS warning light OFF10 ± 14
SRRR (B10 ± 9) ± GND (B10 ±
6, 31, B11 ± 8, 17)R±L e W±BIG switch ON, ABS warning light OFF10 ± 14
VCM (B10 ± 10) ± GND (B10 ±
6, 31, B11 ± 8, 17)B e W±BIG switch ON4.5 ± 5.5
PH (B10 ± 11) ± GND (B10 ± 6,GRWBVehicle stops, pump motor rotates5 ± 7PH (B10 11 ) GND (B10 6,
31, B11 ± 8, 17)GR eW±BVehicle stops, pump motor stopsBelow 1.0
SG1 (B10 ± 12) ± GND (B10 ±
6, 31, B11 ± 8, 17)Shielded eW±BIG switch OFFContinuity
FR+ (B10 ± 14) ± FR± (B10 ±
13)P e LIG switch ON, slowly turn right front wheelPulse generation
FL+ (B10 ± 16) ± FL± (B10 ±
15)R e GIG switch ON, slowly turn left front wheelPulse generation
MT± (B10 ± 18) ± GND (B10 ±
6, 31, B11 ± 8, 17)Y e W±BIG switch OFFContinuity
SR (B10 ± 19) ± GND (B10 ± 6,
31, B11 ± 8, 17)B±L e W±BIG switch ON, ABS warning light OFFBelow 1.5
SFLH (B10 ± 21) ± GND (B10 ±
6, 31, B11 ± 8, 17)Y±B e W±BIG switch ON, ABS warning light OFF10 ± 14
PMC (B10 ± 22) ± GND (B10 ±
6, 31, B11 ± 8, 17)W e W±BIG switch ON, stop light switch OFFBelow 1.0
E2 (B10 ± 23) ± GND (B10 ± 6,
31, B11 ± 8, 17)R e W±BIG switch OFFContinuity
FSS (B10 ± 24) ± GND (B10 ±
6, 31, B11 ± 8, 17)BR e W±BIG switch OFFContinuity

DI±368
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U) MTT (B10 ± 27) ± GND (B10 ±
WLWBIG switch ON, pump motor rotatesAbove 8.0MTT (B10 27) GND (B10
6, 31, B11 ± 8, 17)W±L e W±BIG switch ON, pump motor stopsBelow 1.5
MT+ (B10 ± 28) ± GND (B10 ±
6, 31, B11 ± 8, 17)Y±G e W±BIG switch ON (Motor relay is OFF)Below 1.5
MR1 (B10 ± 29) ± GND (B10 ±
6, 31, B11 ± 8, 17)LG±R e W±BIG switch ON, ABS motor stops10 ± 14
STP (B11 ± 1) ± GND (B10 ± 6,GWWBStop light switch OFFBelow 1.5STP (B11 1) GND (B10 6,
31, B11 ± 8, 17)G±W e W±BStop light switch ON8 ± 14
SP1 (B11 ± 2) ± GND (B10 ± 6,
31, B11 ± 8, 17)V±R e W±BVehicle driving at about 30 km/h (19 mph)Pulse generation
Tc (B11 ± 3) ± GND (B10 ± 6,
31, B11 ± 8, 17)P±B e W±BIG switch ON10 ± 14
Ts (B11 ± 4) ± GND (B10 ± 6,
31, B11 ± 8, 17)GR±G e W±BIG switch ON10 ± 14
BRL (B11 ± 5) ± GND (B10 ± 6,
31, B11 ± 8, 17)R±Y e W±BIG switch OFF " ON (Parking brake switch OFF)10 ± 14 for about 3
sec., then Below 2
IG1 (B11 ± 6) ± GND (B10 ± 6,
31, B11 ± 8, 17)B±Y e W±BIG switch ON10 ± 14
R1+ (B11 ± 7) ± GND (B10 ± 6,
31, B11 ± 8, 17)Y±B e W±BIG switch ON10 ± 14
D/G (B11 ± 10) ± GND (B10 ±
6, 31, B11 ± 8, 17)W±L e W±BIG switch ON10 ± 14
RR+ (B11 ± 11) ± RR± (B11 ±
12)Y e BRIG switch ON, slowly turn right rear wheelPulse generation
HVO+ (B11 ± 14) ± GND (B10
± 6, 31, B11 ± 8, 17)G e W±BIG switch ONAbout 2.5
RLO (B11 ± 15) ± GND (B10 ±
6, 31, B11 ± 8, 17)W e W±BVehicle driving at about 30 km/h (19 mph)Pulse generation
HVI± (B11 ± 16) ± GND (B10 ±
6, 31, B11 ± 8, 17)V e W±BIG switch ONAbout 2.5
WA (B11 ± 18) ± GND (B10 ± 6,BWWBIG switch ON, ABS warning light ON10 ± 14WA (B11 18) GND (B10 6,
31, B11 ± 8, 17)B±W e W±BIG switch ON, ABS warning light OFFBelow 2.0
RL+ (B11 ± 19) ± RL± (B11 ±
20)P e LIG switch ON, slowly turn left rear wheelPulse generation
RSS (B11 ± 21) ± GND (B10 ±
6, 31, B11 ± 8, 17)BR±B e W±BIG switch OFFContinuity
HVO± (B11 ± 22) ± GND (B10 ±
6, 31, B11 ± 8, 17)R e W±BIG switch ONAbout 2.5
RRO (B11 ± 23) ± GND (B10 ±
6, 31, B11 ± 8, 17)B e W±BVehicle driving at about 30 km/h (19 mph)Pulse generation
HVI+ (B11 ± 24) ± GND (B10 ±
6, 31, B11 ± 8, 17)LG e W±BIG switch ONAbout 2.5
IG2 (B12 ± 1) ± GND (B10 ± 6,
31, B11 ± 8, 17)B±W e W±BIG switch ON10 ± 14
LBL (B12 ± 7) ± GND (B10 ± 6,
31, B11 ± 8, 17)LG±R e W±BIG switch ON, fluid in master cylinder reservoir above MIN level4.5 ± 6.4
VFR (B12 ± 9) ± GND (B10 ± 6,
31, B11 ± 8, 17)B e W±BIG switch ON4.5 ± 5.5
PKB (B12 ± 13) ± GND (B10 ±RYWBIG switch ON, parking brake switch ONBelow 1.5PKB (B12 13) GND (B10
6, 31, B11 ± 8, 17)R±Y e W±BIG switch ON, parking brake switch OFF10 ± 14

± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±369
2001 PRIUS (RM778U) SG2 (B12 ± 15) ± GND (B10 ±
6, 31, B11 ± 8, 17)
Shielded e W±BIG switch OFFContinuity
VREG (B12 ± 16) ± GND (B10
± 6, 31, B11 ± 8, 17)B e W±BIG switch ON4.5 ± 5.5
SG3 (B12 ± 18) ± GND (B10 ±
6, 31, B11 ± 8, 17)Shielded e W±BIG switch OFFContinuity
BZ (B12 ± 20) ± GND (B10 ± 6,GWBIG switch ON, buzzer soundsBelow 1.5BZ (B12 20) GND (B10 6,
31, B11 ± 8, 17)G e W±BIG switch ON, buzzer does not sound10 ± 14
EREG (B12 ± 24) ± GND (B10
± 6, 31, B11 ± 8, 17)R e W±BIG switch OFFContinuity
PREG (B12 ± 25) ± GND (B10
± 6, 31, B11 ± 8, 17)W e W±BIG switch ON, brake pedal releasedBelow 1.0
EFR (B12 ± 27) ± GND (B10 ±
6, 31, B11 ± 8, 17)R e W±BIG switch OFFContinuity
PFR (B12 ± 28) ± GND (B10 ±
6, 31, B11 ± 8, 17)W e W±BIG switch ON, brake pedal releasedBelow 1.0
SLA+ (B13 ± 1) ± GND (B10 ±
6, 31, B11 ± 8, 17)L e W±BIG switch ONPulse generation
MR2 (B13 ± 2) ± GND (B10 ± 6,YGWBIG switch ON, pump motor rotatesBelow 1.0MR2 (B13 2) GND (B10 6,
31, B11 ± 8, 17)Y±G e W±BIG switch ON, pump motor stops10 ±14
R2+ (B13 ± 3) ± GND (B10 ± 6,
31, B11 ± 8, 17)L±O e W±BIG switch ON10 ± 14
VRR (B13 ± 5) ± GND (B10 ± 6,
31, B11 ± 8, 17)B e W±BIG switch ON4.5 ± 5.5
AST (B13 ± 6) ± GND (B10 ± 6,
31, B11 ± 8, 17)B±O e W±BIG switch ON, ABS warning light OFF10 ± 14
SLR± (B13 ± 7) ± GND (B10 ±
6, 31, B11 ± 8, 17)V e W±BIG switch ONBelow 1.5
SLA± (B13 ± 8) ± GND (B10 ±
6, 31, B11 ± 8, 17)LG e W±BIG switch ONBelow 1.5
PL (B13 ± 9) ± GND (B10 ± 6,
31, B11 ± 8, 17)Y±R e W±BIG switch OFF, depress brake pedal more than 40 times " IG
switch ON6.5 ± 10 " 2.5 ± 5.0
PRR (B13 ± 13) ± GND (B10 ±
6, 31, B11 ± 8, 17)W e W±BIG switch ON, brake pedal releasedBelow 1.0
SLR+ (B13 ± 16) ± GND (B10 ±
6, 31, B11 ± 8, 17)P e W±BIG switch ONPulse generation
SG4 (B13 ± 19) ± GND (B10 ±
6, 31, B11 ± 8, 17)Shielded e W±BIG switch OFFContinuity
ERR (B13 ± 20) ± GND (B10 ±
6, 31, B11 ± 8, 17)R e W±BIG switch OFFContinuity
+BS (B13 ± 22) ± GND (B10 ±
6, 31, B11 ± 8, 17)Le W±BIG switch ON10 ± 14

F12673
B±G
F111
L4 Instrument
Panel J/B
DC/DC FL Block No. 1
3
Brake
Combination Meter
W±B
Brake Fluid
Level Warning
Switch7Brake ECU
LBL
C11
J7
J/C AM1162K
IE 2A
ID22B11
WR±Y
MAINLG±R
12
14
A W±G B±Y
IG1
RelayBRL
B12
C11
C10
C105 Body ECU
B8 B8
15
BR2
2 W±B
A A
J1
J/C AW±BInstrument
Panel J/B
Battery FL
Block
No. 21
F13
Ignition Switch
24
2H 2B 2D
2K2A 5 1
3 6
5 1
3
27
8GAUGE
LMultiplex Communication Circuit
IH 2B 6 1
J11
J/CGR±B GR
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
DI±385
2001 PRIUS (RM778U)
DTC C1202/58 Brake Fluid Warning Switch Circuit
CIRCUIT DESCRIPTION
The brake fluid level warning switch sends the appropriate signal to the ECU when the brake fluid level drops.
HINT:
Depressing the parking brake pedal also turns on the brake warning light but does not diagnose DTC No.
C1202/58.
DTC No.DTC Detecting ConditionTrouble Area
C1202/58
When any of the following 1. 2. or 3. is detected:
1. When the ignition switch is ON, an open condition in the
reservoir level switch circuit continues for 2 sec. or
more.
2. While a vehicle is driven at a speed of 3 km/h (5 mph) or
more, decrease in the reservoir level continues for 10
sec. or more.
3. While a vehicle is stopped, decrease in the reservoir
level continues for 5 sec. or more.

Brake fluid level

Brake fluid level warning switch

Brake fluid level warning switch circuit
WIRING DIAGRAM
DI1GZ±10

DI±386
± DIAGNOSTICSANTI±LOCK BRAKE SYSTEM WITH EBD & RBS
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check brake fluid level.
CHECK:
Check the amount of fluid in the brake reservoir.
NG Check and repair brake fluid leakage and add
fluid.
OK
2 Check brake fluid level warning switch (See page BE±2).
NG Replace brake fluid level warning switch.
OK
3 Check for open circuit in all the harness and components connected to brake
fluid level warning light (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace brake ECU.

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.