CAN COMMUNICATION SYSTEM(w/ Toyota Safety Sense) 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 correspond to "Main Body ECU Communication Stop Mode" in "DTC Combination Table" are output.

    Click here


  • 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

A004G5NE01

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 (-) auxiliary 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 (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Click here.

  • 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.

  • 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 (IG), turn the cruise control system on using the cruise control main switch (ON/OFF switch), wait at least 60 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more.

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

Tech Tips


  • 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 (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) BRANCH LINE)


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

    2. A004FLEE02
      Text in Illustration
      *a

      Front view of wire harness connector

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

      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
      F57-14 (CANH) - F57-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

    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. A004FLPE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

      Disconnect the instrument panel junction block assembly connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3B-8 (GND1) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω
    3. A004FQ0E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

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

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      3C-21 (BECU) - Body ground Ignition switch off 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

  3. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY AND ACC RELAY)


    1. Remove the instrument panel junction block assembly Click here.

    2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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

      A004FG9E02
      Text in Illustration
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      3E-1 - MB-32 (IG) Always 10 kΩ or higher
      3E-1 - MB-32 (IG)

      Auxiliary battery positive (+) → 3A-29

      Auxiliary battery negative (-) → 3B-8

      		 Below 1 Ω
      3E-1 - MB-29 (ACC) Always 10 kΩ or higher
      3E-1 - MB-29 (ACC)

      Auxiliary battery positive (+) → 3B-37

      Auxiliary battery negative (-) → 3B-8

      		 Below 1 Ω

    OK

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

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here