LEXUS LS430 2003 Factory Repair Manual

Fig. 66: Disconnecting Suspension Control ECU Connector (A20)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Turn the ignition switch to the LOCK position.
b. Disconnect the suspension control ECU connector (A20).
c. Measure the resistance according to the value (s) in the table below.
Standard:
SUSPENSION CONTROL ECU CONNECTOR TERMINALS RESISTANCE
NG: REPAIR OR REPLACE SUSPENSION CONTROL ECU SUB BUS LINE OR CONNECTOR
(CAN-H, CAN-L)
OK: GO TO NEXT STEP
2.CHECK WIRE HARNESS (B, GND)
Tester connectionConditionSpecified value
A20-7 (CANH) - A20-8 (CANL)Ignition Switch OFF54 to 69 ohms

Fig. 67: Disconnecting Suspension Control ECU Connector (A20)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Measure the resistance according to the value (s) in the table below.
b. Measure the voltage according to the value (s) in the table below.
Standard:
SUSPENSION CONTROL ECU CONNECTOR TERMINALS RESISTANCE AND VOLTAGE
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK: REPLACE SUSPENSION CONTROL ECU (SEE REPLACEMENT
)
MODE DESCRIPTION
Tester connectionConditionSpecified value
A20-4 (GND) - Body groundAlwaysBelow 1 ohms
A20-1 (B) - Body groundIgnition Switch ON10 to 14 V

Fig. 68: Problem Symptom Diagnostic Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM
Fig. 69: Wiring Diagram
- Seat Belt Control ECU Communication Stop Mode

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK CAN BUS LINE FOR DISCONNECTION (SEAT BELT CONTROL ECU SUB BUS
LINE)
Fig. 70: Disconnecting Seat Belt Control ECU Connector (S63)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Turn the ignition switch to the LOCK position.
b. Disconnect the seat belt control ECU connector (S63).
c. Measure the resistance according to the value (s) in the table below.
Standard:
SEAT BELT CONTROL ECU CONNECTOR TERMINALS RESISTANCE
NG: REPAIR OR REPLACE SEAT BELT CONTROL ECU SUB BUS LINE OR CONNECTOR
Tester connectionConditionSpecified value
S63-4 (CANH) - S63-6 (CANL)Ignition Switch OFF54 to 69 ohms

OK: GO TO NEXT STEP
2.CHECK WIRE HARNESS (IG, GND)
Fig. 71: Disconnecting Seat Belt Control ECU Connector (S63)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the seat belt control ECU connector (S63).
b. Measure the resistance according to the value (s) in the table below.
c. Measure the voltage according to the value (s) in the table below.
Standard:
SEAT BELT CONTROL ECU CONNECTOR TERMINALS RESISTANCE AND VOLTAGE
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
Tester ConnectionConditionSpecified Condition
S63-18 (GND) - Body groundAlwaysBelow 1 ohms
S63-9 (+B) - Body groundAlways10 to 14 V
S63-3 (IG) - Body groundIgnition Switch ON10 to 14 V

OK: REPLACE SEAT BELT CONTROL ECU
CIRCUIT DESCRIPTION
There may be an open circuit in the CAN main bus line and/or the DLC3 sub bus line when the resistance
between terminals 6 (CANH) and 14 (CANL) of the DLC3 is 69 ohms or more.
Fig. 72: Problem Symptom Diagnostic Chart

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

Fig. 73: Wiring Diagram - Can Main Bus Line For Disconnection (W/ LEXUS Navigation System)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK DLC3

Fig. 74: Identifying DLC3 Connector terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Turn the ignition switch to the LOCK position.
b. Measure the resistance according to the value (s) in the table below.
Result:
DLC3 CONNECTOR TERMINALS RESISTANCE
Tester connectionConditionSpecified valueResult
D1-6 (CANH) - D1-14 (CANL)Ignition Switch OFF108 to 132 ohmsA
D1-6 (CANH) - D1-14 (CANL)Ignition Switch OFF132ohms or moreB

B: REPAIR OR REPLACE DLC3 SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L)
A: GO TO NEXT STEP
2.CHECK CAN MAIN BUS LINE FOR DISCONNECTION (D-CAN J/C)
Fig. 75: Identifying CAN Main Bus Line Connector (J37)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the CAN main bus line connector (J37) from the D-CAN J/C A side (w/earth terminal).

b. Measure the resistance according to the value (s) in the table below.
Standard:
CAN MAIN BUS LINE CONNECTOR TERMINALS RESISTANCE
OK: REPLACE JUNCTION CONNECTOR (D-CAN J/C)
NG: GO TO NEXT STEP
3.CONNECT CONNECTOR
a. Reconnect the CAN main bus line connector (J37) to the D-CAN J/C.
4.CHECK CAN MAIN BUS LINE FOR DISCONNECTION (D-CAN J/C - P-CAN J/C)
Tester connectionConditionSpecified value
J37-1 (CANH) - J37-2 (CANL)Ignition Switch OFF108 to 132 ohms