Lexus IS250 · Service Manual COMMUNICATION SYSTEM

Open in CAN Main Bus Line

Circuit diagnosis

DESCRIPTION

There may be an open circuit in the CAN main bus line and/or the DLC3 branch line when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is 69 Ω or more.
Symptom
 Trouble Area
The resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is 69 Ω or more.
  1. CAN main bus line or connector
  1. CAN LH J/C
  1. CAN RH J/C
  1. DLC3 branch line or connector

WIRING DIAGRAM

C127766E03

INSPECTION PROCEDURE


1. CHECK DLC3

  1. Turn the engine switch off.

  1. C126231E01
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    		 Result
    J21-6 (CANH) -J21-14 (CANL)
    		 Engine switch off
    		 108 to 132 Ω
    		 A
    J21-6 (CANH) - J21-14 (CANL)
    		 Engine switch off
    		 132 Ω or higher
    		 B

    NOTICE:
    When the measured value is 132 Ω or more and a CAN communication system diagnostic trouble code is output, there may be a fault besides disconnection of the DLC3 branch line. For that reason, troubleshooting should be performed again from "HOW TO PROCEED WITH TROUBLESHOOTING" (Click here ) after repairing the trouble area.



 B
REPAIR OR REPLACE DLC3 BRANCH LINE OR CONNECTOR (CANH, CANL)
A


2. CHECK FOR OPEN IN CAN MAIN BUS LINE (BUS CHECK)

  1. Perform "Communication Bus Check" using the intelligent tester (Click here).

    Result:
    Specified Condition
    		 Proceed to
    "BODY/GATEWAY" only is not displayed
    		 A
    "ENGINE and ECT" only are not displayed
    		 B
    Others
    		 C



B
Go to step 4

C
Go to step 7
A


3. CHECK FOR OPEN IN CAN MAIN BUS LINE (GATEWAY ECU - CAN RH J/C)

  1. G031972E14
    Turn the engine switch off.

  1. Disconnect the gateway ECU connector (J76).

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    J76-17 (CA1H) - J76-18 (CA1L)
    		 Engine switch off
    		 108 to 132 Ω



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN RH J/C - GATEWAY ECU)
OK

REPLACE GATEWAY ECU

4. CHECK FOR OPEN IN CAN MAIN BUS LINE (ECM - CAN RH J/C)

  1. C123382E01
    Turn the engine switch off.

  1. Disconnect the ECM connector (A5).

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    A5-25 (CANH) - A5-24 (CANL)
    		 Engine switch off
    		 108 to 132 Ω



OK
REPLACE ECM
NG


5. RECONNECT CONNECTOR

  1. Reconnect the ECM connector (A5).


NEXT


6. CHECK FOR OPEN IN CAN MAIN BUS LINE (CAN LH J/C - ECM)

  1. G031934E60
    Disconnect the CAN main bus line connector (J2) from the CAN LH J/C B side (with earth terminal).

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    J2-1 (CANH) - J2-2 (CANL)
    		 Engine switch off
    		 108 to 132 Ω



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (ECM - CAN LH J/C)
OK

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN LH J/C - CAN RH J/C)

7. CHECK FOR OPEN IN CAN MAIN BUS LINE (ECM - CAN LH J/C)

  1. C123382E01
    Turn the engine switch off.

  1. Disconnect the ECM connector (A5).

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    A5-25 (CANH) - A5-24 (CANL)
    		 Engine switch off
    		 108 to 132 Ω



OK
REPLACE ECM
NG


8. RECONNECT CONNECTOR

  1. Reconnect the ECM connector (A5).


NEXT


9. CHECK FOR OPEN IN CAN MAIN BUS LINE (GATEWAY ECU - CAN LH J/C)

  1. G031972E14
    Disconnect the gateway ECU connector (J76).

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    J76-17 (CA1H) - J76-18 (CA1L)
    		 Engine switch off
    		 108 to 132 Ω



OK
REPLACE GATEWAY ECU
NG


10. RECONNECT CONNECTOR

  1. Reconnect the gateway ECU connector (J76).


NEXT


11. CHECK FOR OPEN IN CAN MAIN BUS LINE (CAN RH J/C - GATEWAY ECU)

  1. G031932E90
    Disconnect the CAN main bus line connector (J84) from the CAN RH J/C B side (without earth terminal).

    NOTICE:
    1. Before disconnecting the connector, make a note of where it is connected.
    2. Reconnect the connector to its original position.

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    J84-1 (CANH) - J84-2 (CANL)
    		 Engine switch off
    		 108 to 132 Ω



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN RH J/C - GATEWAY ECU)
OK


12. RECONNECT CONNECTOR

  1. Reconnect the CAN main bus line connector (J84) to the CAN RH J/C B side (without earth terminal).


NEXT


13. CHECK FOR OPEN IN CAN MAIN BUS LINE (ECM - CAN LH J/C)

  1. G031934E60
    Disconnect the CAN main bus line connector (J2) from the CAN LH J/C A side (with earth terminal).

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Value
    J2-1 (CANH) - J2-2 (CANL)
    		 Engine switch off
    		 108 to 132 Ω



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (ECM - CAN LH J/C)
OK

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN LH J/C - CAN RH J/C)


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