LEXUS LS430 2003 Factory Repair Manual

1.CHECK DRIVER SEAT ECU
Fig. 7: Identifying Terminals Of Driver Seat ECU

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the D27 and D28 ECU connectors.
b. Measure the voltage of the wire harness side connectors.
Standard:
DRIVER SEAT ECU TERMINALS REFERENCE
If the result is not as specified, there may be a malfunction on the wire harness side.
c. Reconnect the D27 and D28 ECU connectors.
d. Initialize the front power seat (SEE INITIALIZATION
).
e. Measure the voltage of connectors.
Standard:
Symbols (Terminal
No.)Wiring ColorTerminal
DescriptionConditionSpecified
Condition
GND (D27-6) - Body
groundW-B - Body
groundGroundAlwaysBelow 1 V
SGND (D28-1) - Body
groundBR - Body
groundGroundAlwaysBelow 1 V
IG (D28-10) - SGND
(D28-1)R-L - BRIgnition switchIgnition switch OFF
--> ON0 V --> 10 to 14
V
+B (D27-14) - GND
(D27-6)B-R - W-BBatteryAlways10 to 14V
SYSB (D28-9) - SGND
(D28-1)V-Y - BRBatteryAlways10 to 14V

Fig. 8: Driver Seat ECU Terminals Reference Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
If the result is not as specified, replace the power seat or the ECU may have a malfunction.

2.CHECK DRIVER DOOR ECU
Fig. 9: Identifying Terminals Of Driver Door ECU

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the D25 ECU connector.
b. Measure the voltage of the wire harness side connector.
Standard:
DRIVER DOOR ECU TERMINALS REFERENCE
If the result is not as specified, there may be a malfunction on the wire harness side.
c. Reconnect the D25 ECU connector.
d. Measure the voltage of the D24 ECU connector.
Standard:
DRIVER DOOR ECU TERMINALS REFERENCE
Symbols (Terminal
No.)Wiring ColorTerminal
DescriptionConditionSpecified
Condition
GND (D25-1) - Body
groundW-B - Body
groundGroundAlwaysBelow 1 V
CPUB (D25-4) - GND
(D25-1)V-Y - W-BBattery (ECU power
source)Always10 to 14 V
SIG (D25-5) - GND
(D25-1)R-L - W-BIgnition power
supplyIgnition switch OFF
--> ON0 V --> 10 to 14
V
BDR (D25-6) - GND
(D25-1)R - W-BBattery (ECU power
source)Always10 to 14 V
Symbols (Terminal
No.)Wiring
ColorTerminal
DescriptionConditionSpecified
Condition
MM (D24-29) - GR - BR-Memory SET Memory SET switch OFF 10 to 14 V

If the result is not as specified, replace the driver door ECU may have a malfunction.
1.DESCRIPTION
a. The seat ECU controls the function of the front power seat control system on the vehicle. Data of
the power front seat control system can be read in the Data Link Connector 3 (DLC3) of the
vehicle. When the system seems to be malfunctioning, use the hand-held tester to check for
malfunctions and perform repairs.
2.CHECK DLC3
HINT:
The vehicle's ECU uses the ISO 15765-4 communication protocol. The terminal arrangement of the
DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
MSWE (D24-28)Wswitch signalMemory SET switch ONBelow 1 V
M1 (D24-21) -MSWE
(D24-28)P - BR-WMemory 1 switch
signalMemory 1 switch OFF Memory
1 switch ON10 to 14 V
Below 1 V
M2 (D24-20) - MSWE
(D24-28)P-B - BR-
WMemory 2 switch
signalMemory 2 switch OFF Memory
2 switch ON10 to 14 V
Below 1 V
M3 (D24-9) - MSWE
(D24-28)P-L - BR-
WMemory 3 switch
signalMemory 3 switch OFF Memory
3 switch ON10 to 14 V
Below 1 V

Fig. 10: Identifying DLC3 Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
DLC3 CONNECTOR TERMINALS REFERENCE
HINT:
Connect the cable of the hand-held tester (with CAN VIM) to the DLC3, turn the ignition switch ON and
attempt to use the hand-held tester. If the screen displays UNABLE TO CONNECT TO VEHICLE, a
problem exists in the vehicle side or the tester side.
If communication is normal when the tester is connected to another vehicle, inspect the DLC3 on
the original vehicle.
If communication is still impossible when the tester is connected to another vehicle, the problem
may be in the tester itself. Consult the Service Department listed in the tester's instruction manual.
Symbols (Terminal No.)Terminal DescriptionConditionSpecified Condition
SIL (7) - SG (5)Bus "+" lineDuring transmissionPulse generation
CG (4) - Body groundChassis groundAlwaysBelow 1 ohms
SG (5) - Body groundSignal groundAlwaysBelow 1 ohms
BAT (16) - Body groundBattery positiveAlways11 to 14 V

Fig. 11: Connecting Cable Of Hand-Held Tester (With CAN VIM) To DLC3
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
3.INSPECT BATTERY VOLTAGE
Standard: 11 to 14 V
If voltage is below 11 V, replace the battery before proceeding.
1.DATA LIST
HINT:
<00380056004c0051004a00030057004b00480003004b0044005100470010004b0048004f00470003005700480056005700480055000a0056000300270024003700240003002f002c0036003700030044004f004f0052005a005600030056005a004c005700
46004b000f0003005600480051005600520055000f00030044[ctuator and other items to be read
without removing any parts. Reading the DATA LIST early in troubleshooting is one way to save time.
a. Connect the hand-held tester (with CAN VIM) to the DLC3.
b. Turn the ignition switch ON.
c. Read the DATA LIST.
Driver seat ECU:

Fig. 12: Driver Seat ECU - Data List Chart (1 Of 3)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 13: Driver Seat ECU - Data List Chart (2 Of 3)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig. 14: Driver Seat ECU - Data List Chart (3 Of 3)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
2.ACTIVE TEST
HINT:
Using the hand-held tester's ACTIVE TEST allows relay, VSV, actuator, and other items to be operated
without removing any parts. Reading the ACTIVE TEST early in troubleshooting is one way to save

time. The DATA LIST can be displayed during the ACTIVE TEST.
a. Connect the hand-held tester (with CAN VIM) to the DLC3.
b. Turn the ignition switch ON.
c. Perform the ACTIVE TEST by following the directions on the tester screen.
Driver seat ECU:
DRIVER SEAT ECU - ACTIVE TEST
CIRCUIT DESCRIPTION
This circuit provides power to operate the driver seat ECU.
This driver seat ECU is built into this power seat switch. The lumbar support switch and the seat cushion switch
are separate from the power seat switch.
WIRING DIAGRAM
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-