CAN COMMUNICATION SYSTEM (for RHD) Short to B+ in CAN Bus Line

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of the DLC3.

Symptom Trouble Area
No resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of DLC3.
  • Short between CAN bus lines and +B

  • ECM

  • Parking brake ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Spiral with sensor cable sub-assembly (steering angle sensor)

  • Yaw rate sensor

  • Combination meter assembly

  • Skid control ECU assembly

  • Power steering ECU assembly

  • Air conditioning amplifier assembly

  • Network gateway ECU

  • Front steering control ECU*

  • Center airbag sensor assembly

  • Multi-media module receiver assembly

  • Certification ECU (smart key ECU assembly)

  • Power management control ECU

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

  • No. 3 CAN junction connector


WIRING DIAGRAM

A01FVJ3E02
A01FUJQE02
A01FR1ZE02

INSPECTION PROCEDURE

Note


  • Before measuring the resistance of the CAN bus, turn the power 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.

  • 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 turning the power switch off, waiting time may be required before disconnecting the cable from the auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the auxiliary battery terminal notice before proceeding with work Click here.

  • If the main body ECU (multiplex network body ECU) is replaced, refer to the Service Bulletin.

  • Before replacing the certification ECU (smart key ECU assembly), refer to the entry and start system (for Entry Function) Click here.

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

  • DTC check procedure: Allow the radar cruise control system (vehicle control mode) to operate for 1 second or more.

  • 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 power 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.

  • Connectors that connect to the CAN junction connector can be distinguished by color of their CAN bus lines. When the connectors have been disconnected from the CAN junction connector, reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

PROCEDURE


  1. CHECK FOR SHORT TO +B IN CAN BUS LINE (DLC3 BRANCH LINE)


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

      A01FRZ9E35
      Text in Illustration
      *1 No. 3 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 3 CAN Junction Connector)

      *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N116 G W DLC3
    2. Disconnect the DLC3 branch line connector from the No. 3 CAN junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

    NG
    OK
  2. CHECK FOR SHORT TO +B IN CAN BUS LINE


    1. Reconnect the DLC3 branch line connector to the No. 3 CAN junction connector.

    2. Disconnect the connectors from the No. 1 CAN junction connector No. 2 CAN junction connector or CAN No. 3 junction connector one at a time.

      Tech Tips

      Disconnect the ECU and sensor connectors other than the DLC3 branch lines and CAN main bus lines between the No. 1 CAN junction connector, No. 2 CAN junction connector and No. 3 CAN junction connector.

    3. A01FSTYE02
      Text in Illustration
      *a Front view of DLC3

      Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 16 (BAT), and between terminals 14 (CANL) and 16 (BAT) of the DLC3 each time a connector is disconnected.

      A01FTT1E01
      Text in Illustration
      *1 No. 1 CAN Junction Connector *2 No. 2 CAN Junction Connector
      *3 No. 3 CAN Junction Connector *4 ECM
      *5 Parking Brake ECU Assembly *6 Front Steering Control ECU (w/ Variable Gear Ratio Steering System)
      *7 Certification ECU (Smart Key ECU Assembly) *8 Network Gateway ECU
      *9 Yaw Rate Sensor *10 Center Airbag Sensor Assembly
      *11 Main Body ECU (Multiplex Network Body ECU) *12 Power Steering ECU Assembly
      *13 Skid Control ECU Assembly *14 DLC3
      *15 Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor) *16 Air Conditioning Amplifier Assembly
      *17 Combination Meter Assembly *18 Multi-media Module Receiver Assembly
      *19 Power Management Control ECU - -
      A01FTEJE04
      Text in Illustration
      *1 No. 1 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 1 CAN Junction Connector)

      - -
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      U48 B W Parking Brake ECU Assembly
      U49 R W Front Steering Control ECU*
      U50 P W No. 2 CAN Junction Connector
      U51 G W ECM

      • *: w/ Variable Gear Ratio Steering System

      A01FUGME08
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      - -
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N107 B W No. 3 CAN Junction Connector
      N108 R W Certification ECU (Smart Key ECU Assembly)
      N109 G W Network Gateway ECU
      N110 B W Yaw Rate Sensor
      N111 Y W Center Airbag Sensor Assembly
      N112 V W Main Body ECU (Multiplex Network Body ECU)
      N113 P W No. 1 CAN Junction Connector
      N114 L W Power Steering ECU Assembly
      A01FUGME09
      Text in Illustration
      *1 No. 3 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 3 CAN Junction Connector)

      - -
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N115 L W Skid Control ECU Assembly
      N116 G W DLC3
      N117 R W Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor)
      N118 Y W Air Conditioning Amplifier Assembly
      N119 V W Combination Meter Assembly
      N120 P W Power Management Control ECU
      N121 B W No. 2 CAN Junction Connector
      N122 B W Multi-media Module Receiver Assembly

      Note

      Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to +B in 2 or more CAN bus lines.

      Result
      Result Proceed to
      The resistance between terminals 6 (CANH) and 16 (BAT), or the resistance between 14 (CANL) and 16 (BAT) is still below 6 kΩ when all the specified connectors are disconnected from the CAN junction connector. (There is a short to +B in the CAN main bus lines between the No. 1 CAN junction connector and No. 2 CAN junction connector or No. 2 CAN junction connector and No. 3 CAN junction connector.) A
      The resistance between terminals 6 (CANH) and 16 (BAT), or the resistance between 14 (CANL) and 16 (BAT) becomes normal (6 kΩ or more) when a connector is disconnected from the CAN junction connector. (There is a short to +B in one of the areas that relate to one or more of the disconnected bus lines.) B
    4. When there is a short to +B in one or more of the bus lines that connect to an ECU (or sensor):


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the bus line that is shorted to +B). Check that the resistance shown on the tester is normal (6 kΩ or more) to confirm that there is a short to +B in the one bus line only.

        Tech Tips


        • The connectors connected to the CAN junction connector can be distinguished according to the color of the communication bus lines and the shape of the connectors.

        • Reconnecting the connectors to non-specified positions on the CAN junction connector does not affect system operation. However, it is preferred to reconnect the connectors to their specified positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

    5. When there is no short to +B in any of the bus lines that connect to the ECUs and sensors:


      1. With all the specified connectors for ECUs and sensors disconnected, proceed with the inspection of the CAN bus main lines between the No. 1 CAN junction connector and No. 2 CAN junction connector or No. 2 CAN junction connector and No. 3 CAN junction connector.


    B
    A
  3. CHECK NO. 1 CAN JUNCTION CONNECTOR


    1. Disconnect the CAN main bus line connector from the No. 1 CAN junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

      A01FVTFE03
      Text in Illustration
      *1 No. 1 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 1 CAN Junction Connector)

      *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      U50 P W No. 2 CAN Junction Connector
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

    NG
    OK
  4. CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the CAN main bus line connector from the No. 1 CAN junction connector.

      A01FRZ9E28
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N113 P W No. 1 CAN Junction Connector
    2. Disconnect the CAN main bus line connector from the No. 2 CAN junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

    NG
    OK
  5. CHECK NO. 2 CAN JUNCTION CONNECTOR


    1. Disconnect the CAN main bus line connector from the No. 2 CAN junction connector.

      A01FRZ9E39
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N107 B W No. 3 CAN Junction Connector

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

    NG
    OK
  6. CHECK SHORT TO +B IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the CAN main bus line connector from the No. 2 CAN junction connector.

      A01FRZ9E03
      Text in Illustration
      *1 No. 3 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 3 CAN Junction Connector)

      *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N121 B W No. 2 CAN Junction Connector
    2. Disconnect the CAN main bus line connector from the No. 3 CAN junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

    NG
    OK
  7. CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU, SENSOR)


    1. A01FSTYE02
      Text in Illustration
      *a Front view of DLC3

      Reconnect the connector of the bus line that is shorted to +B to the CAN junction connector (the connector that caused the bus line resistance to change to 6 kΩ or more when it was disconnected).

    2. Disconnect the connector that includes terminals 6 (CANH) and 14 (CANL) from the ECU (or sensor) to which the bus line shorted to +B is connected Click here.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

      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).


    NG
    OK