CAN COMMUNICATION SYSTEM(for LHD) 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 "CAN Bus Check".

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

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  • Power source circuit of main body ECU (multiplex network body ECU)

  • Main body ECU (multiplex network body ECU) ground circuit

  • Main body ECU (multiplex network body ECU) CAN branch wire or connector

  • Main body ECU (multiplex network body ECU)

  • Instrument panel junction block assembly

WIRING DIAGRAM

Figure 1. w/ Door Control Battery

A01XN0ME02

Figure 2. w/o Door Control Battery

A01XO0KE08

CAUTION / NOTICE / HINT

Note


  • 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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  • Before measuring the resistance of the CAN bus, turn the engine 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 engine switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work.

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  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

  • DTC check procedure: Wait 20 seconds after turning the engine switch on (ACC) or on (IG).

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

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  • Before replacing the main body ECU (multiplex network body ECU) is replaced, refer to the service bulletin.

  • As the door control battery is installed between the vehicle battery and main body ECU (multiplex network body ECU), first perform the inspections in On-Vehicle Inspection to confirm that there are no malfunctions in the power source circuit for the main body ECU (multiplex network body ECU) before performing this troubleshooting procedure.*

    *: w/ Door Control Battery

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Tech Tips


  • Operating the engine switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • 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 WIRE (MAIN BODY ECU BRANCH WIRE)


    1. B005BB2C02
      *a

      Rear view of wire harness connector

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

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

    2. Disconnect the 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
      I48-14 (CANH) - I48-13 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (MAIN BODY ECU)

    OK

  2. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BATTERY AND BODY GROUND)


    1. B005B29C10
      *a

      Front view of wire harness connector

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

      Reconnect the cable to the negative (-) battery terminal.

      Note

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected.

      Click here

    2. Remove the main body ECU (multiplex network body ECU).

      Click here

    3. Reconnect the 4C, 4D and 4F instrument panel junction block assembly connectors.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A-31 (BECU) - Body ground Always 11 to 14 V
      A-32 (IG) - Body ground Engine switch on (IG) 11 to 14 V
      A-30 (ACC) - Body ground Engine switch on (ACC) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A-11 (GND1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

    NG

  3. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BATTERY AND BODY GROUND)


    1. Disconnect the instrument panel junction block assembly connectors.

      B0058GNC02
      *a

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

      		 - -

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      4D-49 - Body ground Always 11 to 14 V
      4F-1 - Body ground Always 11 to 14 V
      4C-28 - Body ground Engine switch on (ACC) 11 to 14 V
      4C-44 - Body ground Engine switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      4D-9 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR