2003 LEXUS LS430 Ecm

Fig. 33: 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.
Standard:
ECM CONNECTOR TERMINALS RESISTANCE
Tester connectionConditionSpecified valueResult
D1-6 (CANH) - D1-14
(CANL)Ignition Switch
OFF54 to 69 ohmsOK
D1-6 (CANH) - D1-14
(CANL)Ignition Switch
OFF69 ohms or more (w/o LEXUS Navigation
system)NG-A
D1-6 (CANH) - D1-14
(CANL)Ignition Switch
OFF69 ohms or more (w/ LEXUS Navigation
System)NG-B
D1-6 (CANH) - D1-14
(CANL)Ignition Switch
OFF54 ohms or less (w/o LEXUS Navigation
System)NG-C

a. Measure the resistance according to the value (s) in the table below.
Standard:
ECM CONNECTOR TERMINALS RESISTANCE
HINT:
NG-A: w/o LEXUS Navigation System.
NG-B: w/ LEXUS Navigation System.
NG-A: CHECK CAN BUS LINE FOR SHORT TO +B (W/O LEXUS NAVIGATION SYSTEM)

NG-B: CHECK CAN BUS LINE FOR SHORT TO +B (W/ LEXUS NAVIGATION SYSTEM)

OK: GO TO NEXT STEP
3.CHECK CAN BUS LINE FOR SHORT TO GND
Tester ConnectionConditionSpecified value
D1-6 (CANH) - D1-16 (BAT)Ignition Switch OFF1 Mohms or more
D1-14 (CANL) - D1-16 (BAT)Ignition Switch OFF1 Mohms or more

Fig. 35: Identifying DLC3 Connector terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Measure the resistance according to the value (s) in the table below.
Standard:
ECM CONNECTOR TERMINALS RESISTANCE
HINT:
NG-A: w/o LEXUS Navigation System.
NG-B: w/ LEXUS Navigation System.
NG-A: CHECK CAN BUS LINE FOR SHORT TO GND (W/O LEXUS NAVIGATION SYSTEM)
Tester ConnectionConditionSpecified value
D1-4 (CG) - D1-6 (CANH)Ignition Switch OFF1 kohms or more
D1-4 (CG) - D1-14 (CANL)Ignition Switch OFF1 kohms or more

Fig. 57: Wiring Diagram - ECM Communication Stop Mode
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INSPECTION PROCEDURE
1.CHECK CAN BUS LINE FOR DISCONNECTION (ECM SUB BUS LINE)
Fig. 58: Disconnecting ECM Connector (E3)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Turn the ignition switch to the LOCK position.
b. Disconnect the ECM connector (E3).
c. Measure the resistance according to the value (s) in the table below.
Standard:
ECM CONNECTOR TERMINALS RESISTANCE
NG: REPAIR OR REPLACE ECM SUB BUS LINE OR CONNECTOR (CAN-H, CAN-L)
Tester connectionConditionSpecified value
E3-25 (CANH) - E3-24 (CANL)Ignition Switch OFF54 to 69 ohms

OK: GO TO NEXT STEP
2.CHECK WIRE HARNESS (+B1, +B, E1)
Fig. 59: Disconnecting ECM Connector (E6)

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a. Disconnect the ECM connector (E6).
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:
ECM CONNECTOR TERMINALS RESISTANCE AND VOLTAGE
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
Tester ConnectionConditionSpecified Condition
E6-7 (E1) - Body groundAlwaysBelow 1 ohms
E3-5 (+B1) - Body groundIgnition Switch ON10 to 14 V
E3-6 (+B) - Body groundIgnition Switch ON10 to 14 V

OK: REPLACE ECM (SEE REPLACEMENT)
MODE DESCRIPTION
Fig. 60: Problem Symptom Diagnostic Chart

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WIRING DIAGRAM

8.CONNECT CONNECTOR
a. Reconnect the gateway ECU sub bus line connector (J36) to the D-CAN J/C A side (w/earth
terminal).
9.CHECK CAN BUS LINES FOR SHORT CIRCUIT (ECM SUB BUS LINE)
Fig. 94: Disconnecting ECM Sub Bus Line Connector (J40) From D
-CAN J/C B Side (W/O Earth
Terminal)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the ECM sub bus line connector (J40) from the D-CAN J/C B side (w/o earth terminal).

10.CONNECT CONNECTOR
a. Reconnect the ECM sub bus line connector (J40) to the D-CAN J/C B side (w/o earth terminal).
11.CHECK CAN BUS LINES FOR SHORT CIRCUIT (SKID CONTROL ECU WITH ACTUATOR
SUB BUS LINE)
Fig. 96: Disconnecting Skid Control ECU Sub Bus Line Connector (J41) From D
-CAN J/C (W/O
Earth Terminal)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the skid control ECU sub bus line connector (J41) from the D-CAN J/C (w/o earth
terminal).