CAN COMMUNICATION SYSTEM Check CAN Bus Line for Short to +B (LHD Models)

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 to +B in CAN main bus line

  • Short to +B in CAN branch line

  • Power management control ECU

  • ECM

  • Main body ECU (Multiplex network body ECU)

  • Combination meter assembly

  • Skid control ECU (Brake booster with master cylinder assembly)

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

  • Yaw rate and acceleration sensor

  • Power steering ECU assembly

  • Airbag sensor assembly

  • Transmission control ECU assembly

  • Certification ECU (Smart key ECU assembly)

  • Navigation ECU (Display and navigation module display)*1

  • Navigation ECU (Navigation computer sub-assembly)*2

  • CAN No. 1 junction connector

  • CAN No. 2 junction connector

  • CAN No. 3 junction connector

*1: w/ Navigation system (for DVD)

*2: w/ Navigation system (for HDD)

WIRING DIAGRAM

A003Y0BE03
A003Z2ZE01

INSPECTION PROCEDURE

Note


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

  • Turn the power switch off before measuring the resistances between CAN main bus lines and between CAN branch lines.

  • Turn the power switch off before inspecting CAN bus lines for a ground short.

  • After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.

  • Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

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.

PROCEDURE


  1. CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 2 J/C)


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

    2. A003X1AE07
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to CAN No. 2 Junction Connector)
      *b to CAN No. 1 Junction Connector
      *c to CAN No. 3 Junction Connector
      *d to DLC3
      *e to Power Steering ECU Assembly
      *f to Navigation ECU

      Disconnect the wire harness connector from the CAN No. 2 junction connector rear side.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H104-1 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher CAN No. 1 junction connector
      H104-2 (CANL) - H44-16 (BAT)
      H104-4 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher CAN No. 3 junction connector
      H104-5 (CANL) - H44-16 (BAT)
      H104-7 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher DLC3
      H104-8 (CANL) - H44-16 (BAT)
      H104-10 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Power steering ECU assembly
      H104-11 (CANL) - H44-16 (BAT)
      H104-13 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Navigation ECU
      H104-14 (CANL) - H44-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (DLC3 branch line) B
      NG (CAN No. 1 junction connector main line) C
      NG (CAN No. 3 junction connector main line) D
      NG (ECU or sensor wire) E

    B

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    C

    CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 1 J/C) Click here

    D

    CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 3 J/C) Click here

    E

    CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR) Click here

    A

  2. CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 2 J/C)


    1. A003X1AE08
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to CAN No. 2 Junction Connector)
      *b to Steering Angle Sensor (Spiral Cable with Sensor Sub-assembly)
      *c to Certification ECU (Smart Key ECU Assembly)
      *d to Airbag Sensor Assembly
      *e to Yaw Rate and Acceleration Sensor

      Disconnect the wire harness connector from the CAN No. 2 junction connector front side.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H105-3 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Steering angle sensor (Spiral cable with sensor sub-assembly)
      H105-2 (CANL) - H44-16 (BAT)
      H105-6 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Certification ECU (Smart key ECU assembly)
      H105-5 (CANL) - H44-16 (BAT)
      H105-9 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Airbag sensor assembly
      H105-8 (CANL) - H44-16 (BAT)
      H105-12 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Yaw rate and acceleration sensor
      H105-11 (CANL) - H44-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (ECU or sensor wire) B

    B

    CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR) Click here

    A

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

  3. CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 1 J/C)


    1. A003X81E01
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to CAN No. 1 Junction Connector)
      *b to Main Body ECU (Multiplex Network Body ECU)
      *c to CAN No. 2 Junction Connector

      Disconnect the instrument panel wire from the CAN No. 1 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H112-5 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Main body ECU (Multiplex network body ECU)
      H112-11 (CANL) - H44-16 (BAT)
      H112-6 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher CAN No. 2 junction connector
      H112-12 (CANL) - H44-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (CAN No. 2 junction connector main line) B
      NG (Main body ECU branch line) C

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 1 J/C - CAN NO. 2 J/C)

    C

    CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR) Click here

    A

  4. CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 1 J/C)


    1. A003X81E02
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to CAN No. 1 Junction Connector)
      *b to ECM
      *c to Skid Control ECU

      Disconnect the engine room main wire from the CAN No. 1 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A57-1 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher ECM
      A57-7 (CANL) - H44-16 (BAT)
      A57-2 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Skid Control ECU (Brake Booster with Master Cylinder Assembly)
      A57-8 (CANL) - H44-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (ECU or sensor wire) B

    B

    CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR) Click here

    A

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

  5. CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 3 J/C)


    1. A003X81E03
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to CAN No. 3 Junction Connector)
      *b to Power Management Control ECU
      *c to CAN No. 2 Junction Connector
      *d to Combination Meter Assembly

      Disconnect the instrument panel wire from the CAN No. 3 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H113-4 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Power management control ECU
      H113-10 (CANL) - H44-16 (BAT)
      H113-5 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher CAN No. 2 junction connector
      H113-11 (CANL) - H44-16 (BAT)
      H113-6 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Combination meter assembly
      H113-12 (CANL) - H44-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (CAN No. 2 junction connector main line) B
      NG (ECU or sensor wire) C

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 3 J/C)

    C

    CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR) Click here

    A

  6. CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 3 J/C)


    1. A003X81E04
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to CAN No. 3 Junction Connector)
      *b to Transmission Control ECU Assembly

      Disconnect the engine room main wire from the CAN No. 3 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A58-1 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Transmission control ECU
      A58-7 (CANL) - H44-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (Transmission control ECU assembly branch line) B

    B

    CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR) Click here

    A

    REPLACE CAN NO. 3 JUNCTION CONNECTOR

  7. CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR)


    1. Reconnect all wire harness connectors (CAN J/C1, CAN J/C2 and CAN J/C3).

    2. Disconnect the ECU or sensor connected to the CAN bus line that is shorted to +B.

      Tech Tips

      If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus lines. To determine the ECU or sensor that is connected to the shorted bus line, refer to the terminals of ECU tables Click here.

    3. A003YN4E25
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H44-6 (CANH) - H44-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      H44-14 (CANL) - H44-16 (BAT)

      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/SENSOR WIRE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR