2001 TOYOTA PRIUS power steering

DI7QX±01
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±465
2001 PRIUS (RM778U)
DIAGNOSTIC TROUBLE CODE CHART
HINT:

Using SST 09843±18040, connect terminals Tc and CG of the DLC3.

If a malfunction code is displayed during the DTC check, check the circuit listed for the code. For details
of each code, turn to the page referred to under the ºSee pageº for respective ºDTC No.º in the DTC
chart.
DTC No.
(See page)Detection ItemTrouble Area
C1511/11
(DI±465)
C1512/12
(DI±465)
T i it lf ti
Torque sensor
C1513/13
(DI±465)Torque sensor circuit malfunction
Torque sensor

EMPS ECU
C1514/14
(DI±465)
C1521/21
(DI±471)
C1522/22
(DI±471)
Mt i it lf ti
Power steering gear assembly with motor
C1523/23
(DI±471)Motor circuit malfunction
Power steering gear assembly with motor

EMPS ECU
C1524/24
(DI±471)
C1531/31
(DI±473)
C1532/32
(DI±473)EMPS ECU malfunctionEMPS ECU
C1533/33
(DI±473)
C1541/41
(DI±474)
C1542/42
(DI±474)Speed sensor malfunction

Speed sensor

Brake ECU

EMPS ECUC1543/43
(DI±474)
EMPS ECU
C1551/51
(DI±476)IG power source circuit malfunction

EMPS ECU

Power source circuit

Charging system
C1552/52
(DI±479)PIG power source drop voltage malfunction
EMPS ECU

Power source circuit
C1553/53
(DI±482)When resetting voltage, vehicle is being drivenEMPS ECU
C1554/54
(DI±483)EMPS relay circuit malfunction

EMPS relay

EMPS ECU

EMPS relay circuit
C1555/55
(DI±473)EMPS ECU malfunctionEMPS ECU
C1556/56
(DI±486)P/S warning light circuit
Multiinformation display

EMPS ECU

DI±466
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)C1557/57
(DI±488)
Memory of overheat prevention control±
C1558/58
(DI±488)Memory of voltage drop at motor power supply±
C1559/59
(DI±488)Memory of continuous control under high load±
Always ON
(DI±489)Malfunction in EMPS ECU

Power source circuit

EMPS ECU

PS warning light circuit

DI7R1±01
F12832
I01
E3
E3
E3
E31
4
2
3EMPS ECU
TRQV
TRQ1
TRQ2
TRQG (Shielded)
W
R
G
B 1 2
3
4 VCC
VT1
VT2
GND Steering Shaft
Torque Sensor
W±B 5
J/C
J18 J19AA
W±B W±B
J17 J/C
A
IG DI±470
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
CIRCUIT INSPECTION
DTC
C1511/11±C1514/14Torque Sensor Circuit Malfunction
CIRCUIT DESCRIPTION
Steering torque is detected from output current of torque sensor.
DTC No.Detection ItemTrouble Area
C1511/11
C1512/12Torque sensor malfunction
Power steering gear assembly with motor
C1513/13
Torque sensor malfunction
Power steering gear assembly with motor

EMPS ECU
C1514/14Open or short torque sensor circuit
WIRING DIAGRAM

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