CAN COMMUNICATION SYSTEM (for LHD) 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

  • Headlight swivel ECU assembly (AFS ECU)

  • Combination meter assembly

  • Brake actuator assembly (skid control ECU)

  • Power steering ECU assembly

  • Air conditioning amplifier assembly

  • Network gateway ECU*1

  • Front steering control ECU*2

  • Center airbag sensor assembly

  • Multi-media module receiver assembly

  • Certification ECU (smart key ECU assembly)

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

  • No. 3 CAN junction connector

WIRING DIAGRAM

A01FEXHE01
A01FFB9E01
A01FFKIE01

INSPECTION PROCEDURE

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, 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.

  • 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 engine 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 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 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.

  • 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 (-) battery terminal.

      A01FG42E02
      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
      N109 G W DLC3

    2. Disconnect the DLC3 branch 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 (-) battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

    NG

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    OK

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


    1. Reconnect the DLC3 branch line connector to the No. 2 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. A01FDXFE02
      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.

      A01FII5E01
      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 Main Body ECU (Multiplex Network Body ECU)
      *7 DLC3 *8 Yaw Rate Sensor
      *9 Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor) *10 Brake Actuator Assembly (Skid Control ECU)
      *11 Headlight Swivel ECU Assembly (AFS ECU) *12 Combination Meter Assembly
      *13 Power Steering ECU Assembly *14 Network Gateway ECU (w/ Network Gateway ECU)
      *15 Multi-media Module Receiver Assembly *16 Air Conditioning Amplifier Assembly
      *17 Center Airbag Sensor Assembly *18 Front Steering Control ECU (w/ Variable Gear Ratio Steering System)
      *19 Certification ECU (Smart Key ECU Assembly) - -
      A01FF4ZE04
      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 Main Body ECU (Multiplex Network Body ECU)
      U50 P W No. 2 CAN Junction Connector
      U51 G W ECM
      A01FIRAE08
      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 Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor)
      N109 G W DLC3
      N110 B W Yaw Rate Sensor
      N111 Y W Headlight Swivel ECU Assembly (AFS ECU)
      N112 V W Combination Meter Assembly
      N113 P W No. 1 CAN Junction Connector
      N114 L W Brake Actuator Assembly (Skid Control ECU)
      A01FIRAE09
      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 Power Steering ECU Assembly
      N116 G W Network Gateway ECU*1
      N117 R W Air Conditioning Amplifier Assembly
      N118 Y W Certification ECU (Smart Key ECU Assembly)
      N119 V W Front Steering Control ECU*2
      N120 P W Center Airbag Sensor Assembly
      N121 B W No. 2 CAN Junction Connector
      N122 B W Multi-media Module Receiver Assembly

      • *1: w/ Network Gateway ECU

      • *2: w/ Variable Gear Ratio Steering System

      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

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

    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.

      A01FH24E03
      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 (-) battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

    NG

    CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR) Click here

    OK

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

  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.

      A01FG42E28
      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 (-) battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

    NG

    CHECK NO. 3 CAN JUNCTION CONNECTOR Click here

    OK

    REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)

  5. CHECK NO. 3 CAN JUNCTION CONNECTOR


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

      A01FG42E03
      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 (-) battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

    NG

    CHECK SHORT TO +B IN CAN BUS LINE (NO. 2 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR) Click here

    OK

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

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


    1. Reconnect the CAN main bus line connector from the No. 3 CAN junction connector.

      A01FG42E37
      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

    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 (-) battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

    NG

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    OK

    REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

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


    1. A01FDXFE02
      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 (-) battery terminal 6 kΩ or higher
      N20-14 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) 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

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR