CAN COMMUNICATION SYSTEM Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the bus 2 main lines and/or bus 2 branch lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the network gateway ECU is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of network gateway ECU is below 54 Ω.

  • Short in CAN main bus line

  • Short in CAN branch line

  • Network gateway ECU

  • ECM

  • Engine Stop and Start ECU (w/ Stop and Start System)

  • No. 4 CAN junction connector (w/ Stop and Start System)

WIRING DIAGRAM

B005M3CE02

CAUTION / NOTICE / HINT

Note


  • 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 or any 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 negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) 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.

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

  • DTC check procedure: Drive the vehicle at a speed of 60 km/h (37 mph) or more for 5 minutes or more, and with the dynamic radar cruise control system operated for 3 seconds or more.

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

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Tech Tips


  • Operating the engine 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 SHORT IN CAN BUS LINES (NETWORK GATEWAY ECU)


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

    2. B005NSTC66
      *a

      Front view of wire harness connector

      (to Network Gateway ECU)

      Disconnect the J75 network gateway ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J75-18 (CA4H) - J75-17 (CA4L) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE NETWORK GATEWAY ECU Click here

    NG

  2. CHECK FOR SHORT IN CAN BUS LINES (ECM)


    1. Reconnect the J75 network gateway ECU connector.

    2. B005MFWC73
      *A w/o Stop and Start System
      *B w/ Stop and Start System
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A37*1 or A46*2 ECM connector.


      • *1: w/o Stop and Start System

      • *2: w/ Stop and Start System

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

      Standard Resistance
      w/o Stop and Start System
      Tester Connection Condition Specified Condition
      A37-13 (CANH) - A37-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      w/ Stop and Start System
      Tester Connection Condition Specified Condition
      A46-13 (CANH) - A46-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK (w/o Stop and Start System) A
      OK (w/ Stop and Start System) B
      NG (w/o Stop and Start System) C
      NG (w/ Stop and Start System) D

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NETWORK GATEWAY ECU - ECM)

    D

  3. CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR)


    1. Reconnect the A37*1 or A46*2 ECM connector.


      • *1: w/o Stop and Start System

      • *2: w/ Stop and Start System

    2. B005NYZC52
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)
      *b to Engine Stop and Start ECU
      *c to ECM
      *d to Network Gateway ECU

      Disconnect the J96 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 Connected to
      J96-9 (CANH) - J96-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Engine stop and start ECU
      J96-10 (CANH) - J96-21 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      J96-11 (CANH) - J96-22 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Network gateway ECU
      Result
      Result Proceed to
      OK A
      NG (ECM main line) B
      NG (Network gateway ECU main line) C
      NG (ECU or sensor branch line) D

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (ECM - NO. 4 CAN JUNCTION CONNECTOR)

    C

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

    D

  4. CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)


    1. Reconnect all wire harness connectors.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

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    3. B005MPFC28
      *a

      Component with harness connected

      (Network Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J75-18 (CA4H) - J75-17 (CA4L) 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.

      Result
      Result
      OK
      NG

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR