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:


  • Communication stop for "Main Body" is indicated on the "Communication Bus Check" screen of the GTS Click here.

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

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

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

  • Power source circuit of cowl side junction block LH

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

  • Cowl side junction block LH ground circuit

  • Main body ECU (multiplex network body ECU)

  • Cowl side junction block LH

WIRING DIAGRAM

B00185CE13

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 Click here.

  • 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 Click here.

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

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

  • DTC check procedure: Turn the engine switch on (IG) and turn the blind spot monitor main switch on, and then wait 13.6 seconds or more.

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

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 CAN BRANCH WIRE)


    1. B001A12E01
      Text in Illustration
      *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
      E118-14 (CANH) - E118-13 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

    NG

    REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO MAIN BODY ECU (CANH, CANL)

    OK

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


    1. B0018O9E02
      Text in Illustration
      *a

      Front view of wire harness connector

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

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

      Note

      When connecting 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 cowl side junction block LH 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-30 (ACC) - Body ground Engine switch on (ACC) 11 to 14 V
      A-32 (IG) - Body ground Engine switch on (IG) 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

    OK

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

    NG

  3. CHECK HARNESS AND CONNECTOR (COWL SIDE JUNCTION BLOCK LH - BATTERY AND BODY GROUND)


    1. Disconnect the cowl side junction block LH connectors.

      B001ABXE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Cowl Side Junction Block LH)

      		 - -

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      2J-23 - Body ground Always 11 to 14 V
      2G-1 - Body ground Always 11 to 14 V
      2J-18 - Body ground Engine switch on (ACC) 11 to 14 V
      2I-18 - 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
      2J-1 - Body ground Always Below 1 Ω

    OK

    REPLACE COWL SIDE JUNCTION BLOCK LH Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR