CAN COMMUNICATION SYSTEM Check Bus 3 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the bus 3 CAN main wires and/or CAN branch wires when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the network gateway ECU is below 54 Ω.

Detection Item Trouble Area
Resistance between terminals 6 (CA3H) and 21 (CA3L) of network gateway ECU is below 54 Ω.

  • Short in bus 3 CAN main wires

  • Short 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 IN CAN BUS WIRES (NO. 4 CAN JUNCTION CONNECTOR)


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

      A002O2SE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Radio and Display Receiver Assembly (for Radio and Display Type)
      *c 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) - H134-7 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio and display receiver assembly*
      H134-2 (CANH) - H134-8 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Network gateway ECU
      H134-3 (CANH) - H134-9 (CANL)

      • *: 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 IN CAN BUS WIRES (ECU, SENSOR) Click here

    B

  2. CONNECT CONNECTOR


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


    NEXT

  3. CHECK FOR SHORT IN CAN BUS WIRES (NETWORK GATEWAY ECU - NO. 4 CAN JUNCTION CONNECTOR)


    1. A002MTFE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Network Gateway ECU)
      *b to No. 4 CAN Junction Connector

      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 Connect to
      H131-6 (CA3H) - H131-21 (CA3L) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 4 CAN junction connector
      H131-19 (CAYH) - H131-20 (CAYL)
      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 IN CAN BUS WIRES (ECU, SENSOR)


    1. A002OT4E02
      Text in Illustration
      *a

      Component with harness connected

      (Network Gateway ECU)

      Reconnect the CAN junction connector.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited CAN branch wire 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) - H131- 21 (CA3L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

      Tech Tips

      If the resistance becomes normal (between 54 and 69 Ω) 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