TOYOTA PRIUS 2001 Service Repair Manual

F12270
ON
TRQV
TRQG
F12271
VT1
VT2
GND
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±471
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminals TRQV and TRQG of EMPS ECU.
PREPARATION:
Remove the EMPS ECU with connectors still connected.
CHECK:
Measure the voltage between terminals TRQV and TRQG of
EMPS ECU connector.
OK:
Voltage: 4.5 ± 5.5 V
NG Check and replace the EMPS ECU.
OK
2 Check for open and short circuit in harness and connector between terminals
TRQV and TRQG of EMPS ECU connector (See page IN±41).
NG Repair and replace harness or connector.
OK
3 Check voltage between terminals VT1 and GND, VT2 and GND of torque sensor
connector.
PREPARATION:
Remove the torque sensor with connectors still connected.
CHECK:
Measure the voltage between terminals VT1 and GND, VT2 and
GND of torque sensor connector.
OK:
Steering PositionVT1VT2
Center position2.1 ± 2.9 V2.1 ± 2.9 V
Right turned0.15 ± 2.9 V2.1 ± 4.85 V
Left turned2.1 ± 4.85 V0.15 ± 2.9 V

DI±472
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
NG Check and replace power steering gear assem-
bly with motor (See page SR±17).
OK
4 Check for open and short circuit in harness and connector between terminals
VT
1 of torque sensor connector and TRQ1 of EMPS ECU connector, VT2 of torque
sensor connector and TRQ
2 of EMPS ECU connector (See page IN±41).
NG Repair and replace harness or connector.
OK
Check and replace EMPS ECU.

DI±474
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
DTC C1516/16 Calibration of Torque Sensor Zero Point Not
Completed
CIRCUIT DESCRIPTION
This DTC does not indicated trouble. This is detected when the torque sensor zero point calibration is not
completed normally.
DTC No.DTC Detecting ConditionTrouble Area
C1516/16This is detected when the torque sensor zero point calibra-
tion is not completed normally.±
INSPECTION PROCEDURE
1 Perform calibration of torque sensor zero point (See page DI±454).
2 Is DTC C1516/16 output?
Check DTC on page DI±460.
NO No problem.
YES
3 Is DTC C1532/32 output?
YES Check and replace EMPS ECU.
NO
4 Perform calibration of torque sensor zero point again (See page DI±454).
DI7R3±01

± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±475
2001 PRIUS (RM778U)
5 Is DTC C1516/16 output after attempted 3 times or more?
YES Replace the power steering gear assembly with
motor.
NO
No problem.

F12834
2
1DC Motor1
2
E4 E4 M1
M2EMPS ECU
B±YY
F12819
ON
M1
M2
DI±476
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
DTCC1521/21±C1524/24Motor Circuit Malfunction
CIRCUIT DESCRIPTION
DTC No.Detection ItemTrouble Area
C1521/21
C1522/22Short circuit of motor terminal or abnormal voltage or current in
Power steering gear assembly with motor
C1523/23
Short circuit of motor terminal or abnormal voltage or current in
motor circuit.

Power steering gear assembly with motor

EMPS ECU
C1524/24
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Check voltage between terminals M1 and M2 of EMPS ECU connector.
PREPARATION:

Remove the EMPS ECU with connectors still connected.

Turn the ignition switch ON.
CHECK:
Turn the steering wheel to left and right and measure the volt-
age between terminals M
1 and M2 of EMPS ECU connector.
OK:
Voltage: 9 ± 14 V
NG Check and replace the EMPS ECU.
DI7R4±01

F12820
M2M1
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±477
2001 PRIUS (RM778U)
OK
2 Check for open and short circuit in harness and connector between terminals M1and M2 of EMPS ECU connector (See page IN±41).
NG Repair or replace harness or connector.
OK
3 Check continuity between terminal M1 and M2 of motor connector.
PREPARATION:
Disconnect the connector from the motor.
CHECK:
Measure the resistance between terminals M1 and M2 of motor
connector.
OK:
Resistance: 0.1 ± 1 W
NG Check and replace the power steering gear as-
sembly with motor (See page SR±17).
OK
Check and replace the EMPS ECU.

F12836
B11
E6 10
4EMPS ECU
WRL
WRR (Shielded)
W
B 15
J/C
J18 J19AA
W±B J17 J/C
A
IGE6
B1123 RLO
RRO BRAKE ECU
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±479
2001 PRIUS (RM778U)
DTCC1541/41±C1543/43Speed Sensor Malfunction
DTC
C1571/71, C1572/72 Speed Sensor Malfunction (Test Mode)
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1541/41
Speed sensor
C1542/42Speed sensor malfunction

Speed sensor

Brake ECU
C1543/43
S eed sensor malfunctionBrake ECU

EMPS ECU
C1571/71S d lf ti (T t d )

Right rear or left rear speed sensor

Sensor installation

Ri
ght rear or left rear speed sensor rotorC1571/71
C1572/72Speed sensor malfunction (Test mode)
Right rear or left rear s eed sensor rotor

Right rear or left rear speed sensor circuit

Brake ECU

EMPS ECU
WIRING DIAGRAM
DI7R6±01

F12822
ON
WRRWRL
PGND
PGND
DI±480
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check continuity between terminals WRR and PGND, WRL and PGND of EMPS
ECU connector.
PREPARATION:
Remove the EMPS ECU with connectors still connected.
CHECK:
Turn the ignition switch ON and measure the resistance be-
tween terminals WRR and PGND, WRL and PGND of EMPS
ECU connector.
OK:
Resistance:1M W or higher
NG Check and replace the EMPS ECU.
OK
2 Check for open and short circuit in harness and connector between terminals
WRR of EMPS ECU connector and RRO of brake ECU connector, WRL of EMPS
ECU and RLO of brake ECU connector (See page IN±41).
NG Repair and replace harness or connector.
OK
3 Check the DTC for the ABS with EBD and RBS (See page DI±351).
*1 Repair ABS with EBD and RBS control system
according to the code output.
*1: Output NG code

F12837
IDE6
2H
2B
2D5
42 3EMPS ECU
IG
IG S/W
Battery ECU±IG
W
IG B±GB±Y 1
23
6
DC/DC AM1
PGND 5J/C
J15
J14DE
W±B
W±B J11
J/C A
F11 B±Y
W±G B±Y
1 IG1 Relay
2
2I
2K8
F18 FL Block No. 2
FL Block No. 1
F1311
1
2
E5 A J17
J/C Instrument Panel J/B
MAIN
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±481
2001 PRIUS (RM778U)
DTC C1551/51 IG Power Source Circuit Malfunction
CIRCUIT DESCRIPTION
The EMPS ECU identifies ON or OFF status of ignition switch by this circuit.
DTC No.DTC Detecting ConditionTrouble Area
C1551/51The abnormal IG voltage value which is not within the specifi-
cation is input to EMPS ECU.
EMPS ECU

Power source circuit

Charging system
WIRING DIAGRAM
DI7R7±01

F12823
ECU±IG Fuse
Instrument Panel J/B
DI±482
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check ECU±IG fuse.
PREPARATION:
Remove the ECU±IG fuse from the instrument panel J/B.
CHECK:
Check the continuity of the ECU±IG.
OK:
Continuity
NG Check for short circuit in all harness and com-
ponents connected to ECU±IG fuse (See at-
tached wiring diagram).
OK
2 Check that the battery positive voltage when IG switch is OFF.
OK:
Voltage: 9 ± 14 V
NG Charge or replace the battery.
OK