2003 LEXUS LS430 Identifying ac

a. Disconnect the D25 ECU connector.
b. Measure the voltage and resistance of the wire harness side connector.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Fig. 20: Identifying D25 Driver Door ECU Connector Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
Tester connectionConditionSpecified condition
D25-4 (CPUB) - Body groundAlways10 to 14 V
D25-6 (BDR) - Body groundAlways10 to 14 V
D25-5 (SIG) - Body groundIgnition switch OFF --> ON0 V --> 10 to 14 V
D25-1 (GND) - Body groundAlwaysBelow 1 ohms

Fig. 22: Identifying D27 Driver Seat ECU Connector Terminals And Power Seat Motor Connector
Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE WIRE HARNESS AND CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
The position sensor detects seat movement and sends pulse signals to the driver seat ECU for use with the
memory function.
The ECU records the number of pulses relative to a previously recorded seat position and uses this data to
return the seat to that position.
If a malfunction occurs in a position sensor and seat movement does not result in pulse signals being input into
the ECU, the memory function is deactivated.
WIRING DIAGRAM

Fig. 25: Identifying D27, D28 Driver Seat ECU Connector Terminals And Power Seat Sensor
Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: GO TO NEXT STEP
3.CHECK DRIVER SEAT ECU (SENSOR POWER SOURCE VOLTAGE)
a. Turn the ignition switch ON.
b. Measure the voltage of the ECU connector.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Fig. 26: Identifying D28 Driver Seat ECU Connector Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE DRIVER SEAT ECU
OK: GO TO NEXT STEP
Tester connectionSpecified condition
D28-16 (PVCC) - Body ground8V

Fig. 27: Identifying D28 Driver Seat ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
A: REPLACE FRONT SEAT HEADREST ADJUSTER
B: REPLACE FRONT POWER SEAT ADJUSTER
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
Pressing the lumbar switch activates the lumbar support motor.
Because the lumbar support switch is not connected to the driver seat ECU, pressing this switch does not
operate ECU operations such as the memory function.
WIRING DIAGRAM

Fig. 29: Identifying Lumbar Support Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE LUMBAR SUPPORT SWITCH
OK: GO TO NEXT STEP
2.INSPECT POWER SEAT MOTOR (SEE INSPECTION
)
NG: REPLACE POWER SEAT MOTOR
OK: GO TO NEXT STEP
3.CHECK WIRE HARNESS (LUMBAR SUPPORT SWITCH - POWER SEAT MOTOR AND
BODY GROUND)
a. Disconnect the P23 switch, connector.
b. Disconnect the P30 and P31 motor connectors.
c. Measure the resistance and voltage of the wire harness side connectors.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Tester connectionSpecified condition
P23-1 (H) - P31-1Below 1 ohms
P23-4 (R) - P31-2Below 1 ohms
P23-2 (H1) - P30-2Below 1 ohms
P23-3 (R1) - P30-1Below 1 ohms
P23-6 (E) - Body groundBelow 1 ohms
P23-5 (B) - P23-6 (E)10 to 14 V

Fig. 30: Identifying P23 Lumbar Support Switch Connector Terminals And P30,P31 Power Seat
Motor Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR AND REPLACE HARNESS AND CONNECTOR

Fig. 32: Identifying Power Seat Cushion Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE POWER SEAT CUSHION SWITCH
OK: GO TO NEXT STEP
2.CHECK WIRE HARNESS (POWER SEAT CONTROL SWITCH - DRIVER SEAT ECU AND
BODY GROUND)
a. Disconnect D28 ECU and P22 switch connectors.
b. Measure the resistance of the wire harness side connectors.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Tester connectionSpecified condition
D28-4 (CSNR) - P22-2 (CSNR)Below 1 ohms
D28-12 (CSNF) - P22-1 (CSNF)Below 1 ohms
P22-4 (E) - Body groundBelow 1 ohms