Page 1625 of 2000

POWER STEERING – ELECTRONIC POWER STEERING SYSTEMPS–25
PS
DESCRIPTION
The power steering ECU supplies the current to the power steering motor through the motor circuit.
WIRING DIAGRAM
INSPECTION PROCEDURE
(a) Connect the intelligent tester (with CAN VIM) to the
DLC3.
(b) Turn the ignition switch ON and press the intelligent
tester main switch ON.
(c) Select the items "MTR TERMINAL(U)", "MTR
TERMINAL(V)", "MTR TERMINAL(W)" in the DATA LIST
and read the value displayed on the intelligent tester.
Power steering ECU
DTC C1524/24 Motor Terminal Voltage Malfunction
DTC No. DTC Detection Condition Trouble Area
C1524/24 Short (or open) in motor circuit or abnormal
voltage or current in motor circuit• Steering column assembly
• Power steering ECU
1READ VALUE OF INTELLIGENT TESTER (MOTOR VOLTAGE)
C128932E01
Item Item Description: Range
(Display)Inspection Condition Reference Value
MTR TERMINAL(U) Motor terminal voltage (U phase):
Min.: 0 V
Max.: 46.667 VSteering wheel is turned While turning the steering wheel,
a value within the range of 1 V to
approximately 0.7 V less than the
battery voltage is displayed. (The
value changes according to the
steering load.)
Page 1626 of 2000

PS–26POWER STEERING – ELECTRONIC POWER STEERING SYSTEM
PS
Result
B
A
MTR TERMINAL(V) Motor terminal voltage (V phase):
Min.: 0 V
Max.: 46.667 VSteering wheel is turned While turning the steering wheel,
a value within the range of 1 V to
approximately 0.7 V less than the
battery voltage is displayed. (The
value changes according to the
steering load.)
MTR TERMINAL(W) Motor terminal voltage (W phase):
Min.: 0 V
Max.: 46.667 VSteering wheel is turned While turning the steering wheel,
a value within the range of 1 V to
approximately 0.7 V less than the
battery voltage is displayed. (The
value changes according to the
steering load.)
Result Proceed to
While turning the steering wheel, a value within the range of 1 V to
approximately 0.7 V less than the battery voltage is displayed. (Power
assist is operating.)A
While turning the steering wheel, 0 V or a value equal to the battery
voltage is displayed. (Power assist is not operating.)B Item Item Description: Range
(Display)Inspection Condition Reference Value
REPLACE STEERING COLUMN ASSEMBLY
REPLACE POWER STEERING ECU
Page 1627 of 2000
POWER STEERING – ELECTRONIC POWER STEERING SYSTEMPS–27
PS
DESCRIPTION
The motor rotation angle sensor detects the motor rotation angle and sends this information to the power
steering ECU.
WIRING DIAGRAM
INSPECTION PROCEDURE
(a) Check the installation condition of the motor rotation
angle sensor connector.
OK:
Motor rotation angle sensor connector is securely
connected to the power steering ECU.
Result
DTC C1528/12 Motor Rotation Angle Sensor Malfunction
DTC No. DTC Detection Condition Trouble Area
C1528/12 Motor rotation angle sensor malfunction • Steering column assembly
• Power steering ECU
1CHECK CONNECTOR CONNECTION CONDITION
C128934E01
Result Proceed to
NG A
OK B
Page 1628 of 2000
PS–28POWER STEERING – ELECTRONIC POWER STEERING SYSTEM
PS
B
A
(a) Reinstall motor rotation angle sensor connector.
(b) Check for DTC.
OK:
DTC is not output.
Result
B
A
(a) Connect the intelligent tester (with CAN VIM) to the
DLC3.
(b) Turn the ignition switch ON and press the intelligent
tester main switch ON.
(c) Select the items "MOTOR ROTATE" in the DATA LIST
and read the value displayed on the intelligent tester.
OK:
During steering operation, motor rotation angle
value changes from 0 to 360
NG
OK Go to step 3
2RECONFIRM DTC
Result Proceed to
DTC is output A
DTC is not output B
END
3READ VALUE OF INTELLIGENT TESTER (MOTOR ROTATION ANGLE SENSOR)
Item Item Description: Range
(Display)Inspection Condition Reference Value
MOTOR ROTATE Motor Rotation Angle:
Min.: 0
Max.: 360
Steering wheel is turned During steering operation, motor
rotation angle value changes from
0 to 360
REPLACE STEERING COLUMN ASSEMBLY
REPLACE POWER STEERING ECU
Page 1629 of 2000
POWER STEERING – ELECTRONIC POWER STEERING SYSTEMPS–29
PS
DESCRIPTION
INSPECTION PROCEDURE
If the power steering ECU detects these DTCs, it will shut off the motor relay circuit (built into the power
steering ECU) and stop power assist. However, power assist continues if DTC C1533 is output.
(a) Check for DTC.
OK:
DTC is not output.
OK
NG
DTC C1531/25 ECU Malfunction
DTC C1532/25 ECU Malfunction
DTC C1533/25 Temperature Sensor Circuit is Low or High
DTC C1534/25 EEPROM Malfunction
DTC No. DTC Detection Condition Trouble Area
C1531/25 ECU internal malfunction (CPU malfunction) Power steering ECU
C1532/25 ECU internal malfunction (Peripheral circuit
malfunction)Power steering ECU
C1533/25 ECU internal malfunction (Substrate
temperature sensor malfunction)Power steering ECU
C1534/25 ECU internal malfunction (EEPROM error) Power steering ECU
1RECONFIRM DTC
PROCEED TO NEXT CIRCUIT INSPECTION
SHOWN IN PROBLEM SYMPTOMS TABLE
REPLACE POWER STEERING ECU
Page 1630 of 2000
PS–30POWER STEERING – ELECTRONIC POWER STEERING SYSTEM
PS
DESCRIPTION
The power steering ECU distinguishes the ignition switch status as ON or OFF through the IG power
source circuit.
WIRING DIAGRAM
INSPECTION PROCEDURE
(a) Connect the intelligent tester (with CAN VIM) to the
DLC3.
(b) Turn the ignition switch ON.
(c) Select the item "IG SUPPLY" in the DATA LIST and read
the value displayed on the intelligent tester.
Power steering ECU
OK
NG
DTC C1551/25 IG Power Supply Voltage Malfunction
DTC No. Detection Condition Trouble Area
C1551/25 IG power source circuit malfunction inside
ECU• ECU-IG1 fuse
• IG power source circuit
• Power steering ECU
1READ VALUE OF INTELLIGENT TESTER (IG POWER SUPPLY)
B128053E03
Item Item Description: Range
(Display)Inspection Condition Specified Condition
IG SUPPLY IG power supply:
Min.: 0 V
Max.: 20.1531 VIgnition switch ON 10 to 14 V
CHECK INTERMITTENT PROBLEMS
Page 1631 of 2000
POWER STEERING – ELECTRONIC POWER STEERING SYSTEMPS–31
PS
(a) Remove the ECU-IG1 fuse from the instrument panel
junction block.
(b) Measure the resistance of the fuse.
OK:
Below 1
NG
OK
(a) Disconnect the E18 and A1 power steering ECU
connectors.
(b) Measure the voltage of the wire harness side
connectors.
Standard voltage
NG
OK
2INSPECT FUSE (ECU-IG1)
REPLACE FUSE
3CHECK HARNESS AND CONNECTOR (BATTERY - POWER STEERING ECU)
F100916E04
Tester Connection Condition Specified Condition
E18 -5 (IG) - A1-2
(PGND)Ignition switch ON 10 to 14 V
REPAIR OR REPLACE HARNESS AND
CONNECTOR
REPLACE POWER STEERING ECU
Page 1632 of 2000
PS–32POWER STEERING – ELECTRONIC POWER STEERING SYSTEM
PS
DESCRIPTION
When a problem occurs in the system, the power source relay circuit is shut off to stop the power assist.
WIRING DIAGRAM
INSPECTION PROCEDURE
(a) Connect the intelligent tester (with CAN VIM) to the
DLC3.
(b) Turn the ignition switch ON.
(c) Select the item "PIG SUPPLY" in the DATA LIST and
read the value displayed on the intelligent tester.
Power steering ECU
OK
NG
DTC C1552/22 PIG Power Supply Voltage Malfunction
DTC No. DTC Detection Condition Trouble Area
C1552/22 PIG power source circuit malfunction inside
ECU• PIG power source circuit
• Power steering ECU
1READ VALUE OF INTELLIGENT TESTER (PIG POWER SUPPLY)
B128054E05
Item Item Description: Range
(Display)Inspection Condition Specified Condition
PIG SUPPLY PIG power supply:
Min.: 0 V
Max.: 20.1531 VPower steering in operation 10 to 14 V
CHECK INTERMITTENT PROBLEMS