CAN COMMUNICATION SYSTEM Check CAN Bus Lines for Short Circuit (LHD Models)

DESCRIPTION

There may be a short circuit between the V bus main lines and/or CAN branch lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CANH) and 14 (CANL) of DLC3 is below 54 Ω.
  • Short in CAN main bus lines

  • Short in CAN branch lines

  • Combination meter assembly

  • Power steering ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Steering sensor

  • Airbag ECU assembly

  • ECM

  • Skid control ECU (brake actuator assembly)

  • Air conditioning amplifier assembly

  • Certification ECU (smart key ECU assembly)

  • Network gateway ECU

  • Radio receiver assembly

  • Yaw rate sensor

  • Stereo component equalizer assembly

  • Spoiler control ECU assembly

  • Torque vectoring differential ECU assembly (w/ Torque Vectoring Differential System)

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

WIRING DIAGRAM

B00662BE02
B0065M3E01

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.

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  • 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: Turn the engine switch on (IG), wait at least 60 seconds, and then drive the vehicle at a speed of 40 km/h (25 mph) or more for 5 minutes 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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  • Before replacing the main body ECU (multiplex network body ECU), ECM or certification ECU (smart key ECU assembly), refer to Service Bulletin.

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 (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)


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

    2. B006531C32
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the O3 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      O3-29 (CANH) - O3-30 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK
    NG
  2. CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the O3 combination meter assembly connector.

    2. B0066J2C41
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A78 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A78-13 (CANH) - A78-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK
    NG
  3. CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the A78 ECM connector.

    2. Disconnect the O104 No. 1 CAN junction connector.

      B00656BC17
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      *b

      to No. 2 CAN Junction Connector

      (for V Bus)

      *c

      to Combination Meter Assembly

      (for V Bus)

      *d

      to Radio Receiver Assembly

      (for V Bus)

      *e

      to Network Gateway ECU

      (for V Bus)

      *f

      to Air Conditioning Amplifier Assembly

      (for V Bus)

      *g

      to Stereo Component Equalizer Assembly

      (for V Bus)

      *h

      to Certification ECU (Smart Key ECU Assembly)

      (for V Bus)

      *i

      Torque Vectoring Differential ECU Assembly

      (w/ Torque Vectoring Differential System)

      (for V Bus)

      *j

      to Power Steering ECU Assembly

      (for V Bus)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      O104-1 (CANH) - O104-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction connector
      O104-2 (CANH) - O104-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      O104-3 (CANH) - O104-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio receiver assembly
      O104-4 (CANH) - O104-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Network gateway ECU
      O104-5 (CANH) - O104-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      O104-6 (CANH) - O104-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Stereo component equalizer assembly
      O104-7 (CANH) - O104-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      O104-8 (CANH) - O104-18 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Torque vectoring differential ECU assembly*
      O104-9 (CANH) - O104-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly

      • *: w/ Torque Vectoring Differential System

      Result
      Result Proceed to
      OK A
      NG (No. 2 CAN junction connector main lines) B
      NG (ECU or sensor branch lines) C
      NG (Combination meter assembly main lines) D

    A
    C
    D
    B
  4. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the O104 No. 1 CAN junction connector.

    2. Disconnect the O105 No. 2 CAN junction connector.

      B00656BC18
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      *b

      to No. 1 CAN Junction Connector

      (for V Bus)

      *c

      to Main Body ECU (Multiplex Network Body ECU)

      (for V Bus)

      *d

      to ECM

      (for V Bus)

      *e

      to Airbag ECU Assembly

      (for V Bus)

      *f

      to Yaw Rate Sensor

      (for V Bus)

      *g

      Spoiler Control ECU Assembly

      (for V Bus)

      *h

      to DLC3

      (for V Bus)

      *i

      to Steering Sensor

      (for V Bus)

      *j

      to Skid Control ECU (Brake Actuator Assembly)

      (for V Bus)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      O105-1 (CANH) - O105-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 1 CAN junction connector
      O105-2 (CANH) - O105-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      O105-3 (CANH) - O105-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      O105-5 (CANH) - O105-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag ECU assembly
      O105-6 (CANH) - O105-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Yaw rate sensor
      O105-7 (CANH) - O105-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Spoiler control ECU assembly
      O105-8 (CANH) - O105-18 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher DLC3
      O105-9 (CANH) - O105-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      O105-10 (CANH) - O105-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      Result
      Result Proceed to
      OK A
      NG (No. 1 CAN junction connector main lines) B
      NG (ECU or sensor branch lines) C
      NG (DLC3 branch lines) D
      NG (ECM main lines) E

    A
    B
    D
    E
    C
  5. 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 lines are connected.

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    3. B0066BBC86
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      O8-6 (CANH) - O8-14 (CANL) 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
    NG