LEXUS LS430 2003 Factory Repair Manual

Fig. 15: ECU Power Source Circuit (Driver Seat ECU) - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

INSPECTION PROCEDURE
1.INSPECT FUSE (D/C CUT, D P/SEAT, MPX-IG, AM1, MPX-B1)
a. Remove the D/C CUT fuse from the FL block.
b. Remove the D P/SEAT, MPX-IG and AM1 fuses from the driver side J/B.
c. Remove the MPX-B1 fuse from the passenger side J/B.
d. Measure the resistance of the fuse.
Standard: Below 1 ohms
NG: REPLACE FUSE
OK: GO TO NEXT STEP
2.INSPECT RELAY (Marking: D-IG1)
a. Remove the D-IG1 relay from the driver side J/B.
b. Measure the resistance of the relay.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Tester connectionSpecified condition
3 - 510 kohms or higher
3 - 5Below 1 ohms (when battery voltage is applied to terminals 1 and 2)

Fig. 16: Identifying D-IG1 Relay Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE RELAY
OK: GO TO NEXT STEP
3.CHECK WIRE HARNESS (DRIVER SEAT ECU - BATTERY AND BODY GROUND)
a. Disconnect the D27 and D28 ECU connectors.
b. Measure the voltage and resistance of the wire harness side connectors.
Fig. 17: Identifying D27 And D28 Driver Seat ECU Connectors Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
This circuit supplies power to operate the driver side J/B ECU.
WIRING DIAGRAM
Tester ConnectionSwitch ConditionSpecified Condition
D27-14 (+B) - Body groundAlways10 to 14 V
D28-9 (SYSB) - Body groundAlways10 to 14 V
D28-10 (IG) - Body groundIgnition switch OFF --> ON0 V --> 10 to 14 V
D27-6 (GND) - Body groundAlwaysBelow 1 ohms
D28-1 (SGND) - Body groundAlwaysBelow 1 ohms

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

NG: REPLACE FUSE
OK: GO TO NEXT STEP
2.INSPECT RELAY (D-IG1)
a. Remove the D-IG1 relay from the driver side J/B.
b. Measure the resistance of the relay.
Standard:
TESTER CONNECTION AND SPECIFIED CONDITION
Fig. 19: Identifying D
-IG1 Relay Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE RELAY
OK: GO TO NEXT STEP
3.CHECK WIRE HARNESS (DRIVER DOOR ECU - BATTERY AND BODY GROUND)
Tester connectionSpecified condition
3 - 510 kohms or higher
3 - 5Below 1 ohms (when battery voltage is applied to terminals 1 and 2)

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

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.

INSPECTION PROCEDURE
1.PERFORM ACTIVE TEST USING HAND-HELD TESTER
a. Connect the hand-held tester (with CAN VIM) to the DLC3.
b. Turn the ignition switch ON and push the hand-held tester (with CAN VIM) main switch ON.
c. Select the ACTIVE TEST on the hand-held tester to generate a control command, and then check
that the power seat operates.
Driver seat ECU:
DRIVER SEAT ECU - ACTIVE TEST
OK: The motor operates normally.
NG: Go to step 2
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS
TABLE
2.INSPECT POWER SEAT MOTOR (SEE INSPECTION
)
NG: REPLACE POWER SEAT MOTOR
OK: GO TO NEXT STEP
3.CHECK WIRE HARNESS (DRIVER SEAT ECU - POWER SEAT MOTOR AND BODY
GROUND)
a. Disconnect the D27 ECU, P27, P28, P29, P32 and P33 motor connectors.
b. Measure the resistance of the wire harness side connectors.
Standard:
ItemTest DetailsDiagnostic Note
RECLININGTest detail: reclining operation FRONT/REAR Vehicle
condition: stopped-
F VERTICALTest detail: front vertical operation UP/DOWN Vehicle
condition: stopped-
LIFTERTest detail: lifter operation UP/DOWN Vehicle condition:
stopped-
SLIDETest detail: sliding operation UP/DOWN Vehicle condition:
stopped-
HEADRESTTest detail: headrest operation UP/DOWN Vehicle condition:
stopped-
CUSHIONTest detail: cushion length operation FRONT/REAR Vehicle
condition: stopped-

TESTER CONNECTION AND SPECIFIED CONDITION
Tester connectionSpecified condition
D27-10 (RCL-) - P32-1Below 1ohms
D27-13 (RCL+) - P32-2Below 1ohms
D27-4 (RRV-) - P29-1Below 1ohms
D27-9 (RRV+) - P29-2Below 1ohms
D27-1 (SLD-) - P33-1Below 1ohms
D27-8 (SLD+) - P33-2Below 1ohms
D27-11 (C-) - P27-2Below 1ohms
D27-7 (C+) - P27-1Below 1ohms
D27-2 (FPV-) - P28-2Below 1ohms
D27-5 (FPV+) - P28-1Below 1ohms
D27-6 (GND) - Body groundBelow 1ohms