CAN COMMUNICATION SYSTEM Main Body ECU Communication Stop Mode

DTC Code DTC Name
Main Body ECU Communication Stop Mode

DESCRIPTION

Detection Item

Symptom

Trouble Area

Main Body ECU Communication Stop Mode

Either condition is met:

  • "Main Body" is not displayed on the CAN Bus Check screen of the GTS

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  • Communication system DTCs (DTCs that start with U) that correspond to "Main Body ECU Communication Stop Mode" in "DTC Combination Table" are output

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  • Main body ECU (multiplex network body ECU) branch line or connector

  • Power source circuit of main body ECU (multiplex network body ECU) or instrument panel junction block assembly

  • Main body ECU (multiplex network body ECU) ground circuit or instrument panel junction block assembly

  • Main body ECU (multiplex network body ECU) or instrument panel junction block assembly

WIRING DIAGRAM

C275940E02
C275939E03
C271568E03

CAUTION / NOTICE / HINT

Note:

  • Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

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  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • DTC check procedure: Turn the ignition switch to ON and wait at least 20 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more.

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed.

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Tip:

  • Operating the ignition switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE

  1. CHECK FOR OPEN IN CAN BUS LINES (MULTIPLEX NETWORK BODY ECU) BRANCH LINE)

    1. Disconnect the cable from the negative (-) battery terminal.

    2. C206279C17

      *a

      Front view of wire harness connector

      (to Main Body ECU (Multiplex Network Body ECU))

      Disconnect the E22 main body ECU (multiplex network body ECU) connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      E22-14 (CANH) - E22-13 (CANL)

      Cable disconnected from negative (-) battery terminal

      54 to 69 Ω

    Result

    Result

    Result

    OK

    NG
    NG

    REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

    OK

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

    1. Disconnect the 3A and 3C instrument panel junction block assembly connectors.

    2. C277515C01

      *a

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      3C-9 (GND1) - Body ground

      Cable disconnected from negative (-) battery terminal

      Below 1 Ω

    3. Connect the cable to the negative (-) battery terminal.

    4. C272557C02

      *a

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      3A-43 (BECU) - Body ground

      Always

      11 to 14 V

    Result

    Result

    Result

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

  3. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 3 RELAY AND ACC RELAY)

    1. Inspect the IG1 No. 3 relay and ACC relay of the instrument panel junction block assembly.

      Tip:

      In case IG signal circuit and ACC signal circuit have no problem, replace the main body ECU (multiplex network body ECU).

    Result

    Result

    Result

    OK

    NG
    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY