CAN COMMUNICATION SYSTEM Check Bus 3 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 6 (CA3H) of the network gateway ECU and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the network gateway ECU and terminal 16 (BAT) of the DLC3.

Detection Item Trouble Area
No resistance exists between terminal 6 (CA3H) of the network gateway ECU and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the network gateway ECU and terminal 16 (BAT) of the DLC3.

  • Short to +B in bus 3 CAN main wires

  • Short to +B in bus 3 CAN branch wires

  • Network gateway ECU

  • Radio and display receiver assembly*

  • No. 4 CAN junction connector

WIRING DIAGRAM

A002OCSE05

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 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 battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.

  • 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 ignition 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 SHORT TO B+ IN CAN BUS WIRE (NO. 4 CAN JUNCTION CONNECTOR)


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

      A002QX9E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b Front view of DLC3
      *c to Radio and Display Receiver Assembly (for Radio and Display Type) *d to Network Gateway ECU

    2. Disconnect the No. 4 CAN junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connect to
      H134-1 (CANH) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Radio and display receiver assembly*
      H134-7 (CANL) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      H134-2 (CANH) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Network gateway ECU
      H134-8 (CANL) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      H134-3 (CANH) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Network gateway ECU
      H134-9 (CANL) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      • *: for Radio and Display Type

      Result
      Result Proceed to
      OK A
      NG (Network gateway ECU CAN main wire) B
      NG (ECU or sensor CAN branch wires) C

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT TO B+ IN CAN BUS WIRE (ECU, SENSOR) Click here

    B

  2. CONNECT CONNECTOR


    1. Reconnect the H134 No. 4 CAN junction connector.


    NEXT

  3. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NETWORK GATEWAY ECU - NO. 4 CAN JUNCTION CONNECTOR)


    1. A002NMZE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Network Gateway ECU)
      *b Front view of DLC3

      Disconnect the network gateway ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H131-6 (CA3H) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      H131-21 (CA3L) - H16-16 (BAT)
      H131-19 (CAYH) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      H131-20 (CAYL) - H16-16 (BAT)
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE NETWORK GATEWAY ECU Click here

    B

    REPLACE NETWORK GATEWAY ECU Click here

    C

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NETWORK GATEWAY ECU - NO. 4 CAN JUNCTION CONNECTOR)

  4. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (ECU, SENSOR)


    1. A002OFFE02
      Text in Illustration
      *a

      Component with harness connected

      (Network Gateway ECU)
      *b Front view of DLC3

      Reconnect the CAN junction connector.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the bus line shorted to +B is connected

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H131-6 (CA3H) - H16-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      H131-21 (CA3L) - H16-16 (BAT)

      Tech Tips

      If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.


    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR CAN BRANCH WIRES OR CONNECTOR