2003 LEXUS LS430 Diagram AC

Fig. 18: Power Source Circuit (Driver Door ECU) - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT FUSE (MPX-B1, AM1, MPX-IG, D DOOR)
a. Remove the MPX-IG and AM1 fuses from the driver side J/B.
b. Remove the D DOOR and MPX-B1 fuses from the passenger side J/B.
c. Measure the resistance of the fuse.
Standard: Below 1 ohms

CIRCUIT DESCRIPTION
The driver seat ECU receives signals from the power seat control switches and operates each power seat motor
according to its switch position.
WIRING DIAGRAM
Fig. 21: Power Seat Motor Wiring Diagram

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

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. 23: Position Sensor Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

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. 28: Lumbar Support Switch Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT LUMBAR SUPPORT SWITCH
a. Remove the lumbar support switch.
b. Measure the resistance.
Standard:
Upper side control
TESTER CONNECTION AND SPECIFIED CONDITION

OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
Pressing the seat cushion switch activates the seat cushion motor.
WIRING DIAGRAM
Fig. 31: Power Seat Cushion Switch Wiring Diagram

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT POWER SEAT CUSHION SWITCH
a. Remove the power seat cushion switch.
b. Measure the resistance of the switch.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION

OK:
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE

CIRCUIT DESCRIPTION
The driver door ECU detects the condition of the driving memory switch, and sends the information to the
power seat ECU and the tilt and telescopic ECU via the multiplex communication circuit.
WIRING DIAGRAM
Fig. 34: Driving Position Memory Switch (W/ Memory) Wiring Diagram

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.READ VALUE OF HAND-HELD TESTER
a. Connect the hand-held tester (with CAN VIM) to the DLC3.
b. Turn the ignition switch ON and press the hand-held tester main switch ON.
c. Select the items below in the DATA LIST, and read the displa
ys on the hand-held tester.