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 in CAN main bus line

  • Short in CAN branch line

  • Combination meter assembly

  • Radio and display receiver assembly*

  • Air conditioning amplifier assembly

  • Power steering ECU assembly

  • Certification ECU (Smart key ECU assembly)

  • Transmission control ECU assembly

  • Airbag sensor assembly

  • Power management control ECU

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

  • Main body ECU (Multiplex network body ECU)

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

  • ECM

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

  • No. 3 CAN junction connector

*: for Radio and display type

WIRING DIAGRAM

A01G2UEE01
A01G2VWE01

CAUTION / NOTICE / HINT

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 or any 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.

  • 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.

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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 power switch on (IG) and wait at least 60 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) 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 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 (NO. 2 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the E118 No. 2 CAN junction connector.

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

      A01G2OGC20
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to No. 3 CAN Junction Connector
      *c to Airbag Sensor Assembly *d to Power Steering ECU Assembly
      *e to Certification ECU (Smart Key ECU Assembly) *f to Combination Meter Assembly
      *g to Power Management Control ECU *h to Radio and Display Receiver Assembly*
      *i to Air Conditioning Amplifier Assembly *j to Transmission Control ECU Assembly

      *: for Radio and display type

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      E118-1 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher No. 3 CAN junction connector
      E118-12 (CANL) - E11-16 (BAT)
      E118-2 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Airbag sensor assembly
      E118-13 (CANL) - E11-16 (BAT)
      E118-5 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Power steering ECU assembly
      E118-16 (CANL) - E11-16 (BAT)
      E118-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Certification ECU (Smart key ECU assembly)
      E118-17 (CANL) - E11-16 (BAT)
      E118-7 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Combination meter assembly
      E118-18 (CANL) - E11-16 (BAT)
      E118-8 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Power management control ECU
      E118-19 (CANL) - E11-16 (BAT)
      E118-9 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Radio and display receiver assembly*
      E118-20 (CANL) - E11-16 (BAT)
      E118-10 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Air conditioning amplifier assembly
      E118-21 (CANL) - E11-16 (BAT)
      E118-11 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Transmission control ECU assembly
      E118-22 (CANL) - E11-16 (BAT)

      *: for Radio and display type

      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor bus line) C

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 4 Click here

    B

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


    1. Disconnect the A32 No. 1 CAN junction connector.

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

      A01G2OGC21
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b to Skid Control ECU (Brake Booster with Master Cylinder Assembly)
      *c to ECM *d to No. 3 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A32-9 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Skid control ECU (Brake booster with master cylinder assembly)
      A32-20 (CANL) - E11-16 (BAT)
      A32-10 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher ECM
      A32-21 (CANL) - E11-16 (BAT)
      A32-11 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher No. 3 CAN junction connector
      A32-22 (CANL) - E11-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor bus line) C

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 4 Click here

    B

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


    1. Disconnect the E119 No. 3 CAN junction connector.

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

      A01G2OGC22
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to No. 1 CAN Junction Connector
      *c to DLC3 *d to Steering Sensor (Spiral Cable with Sensor Sub-assembly)
      *e to Main Body ECU (Multiplex Network Body ECU) *f to No. 2 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      E119-1 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher No. 1 CAN junction connector
      E119-12 (CANL) - E11-16 (BAT)
      E119-2 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher DLC3
      E119-13 (CANL) - E11-16 (BAT)
      E119-3 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Steering sensor (Spiral cable with sensor sub-assembly)
      E119-14 (CANL) - E11-16 (BAT)
      E119-4 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Main body ECU (Multiplex network body ECU)
      E119-15 (CANL) - E11-16 (BAT)
      E119-5 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher No. 2 CAN junction connector
      E119-16 (CANL) - E11-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (No. 1 CAN junction connector main line) B
      NG (No. 2 CAN junction connector main line) C
      NG (ECU or sensor bus line) D
      NG (DLC3 branch line) E

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

    C

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

    E

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    D

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


    1. Reconnect all wire harness connectors (No. 1 CAN junction connector, No. 2 CAN junction connector and No. 3 CAN junction connector).

    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 Terminals of ECU.

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    3. A01G3XHC20
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E11-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      E11-14 (CANL) - E11-16 (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).

      Result
      Result
      OK
      NG

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR