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

  • Combination meter assembly

  • Power steering ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Steering sensor

  • Airbag sensor assembly

  • ECM

  • Skid control ECU (brake actuator assembly)

  • Air conditioning amplifier assembly

  • Certification ECU (smart key ECU assembly)

  • Network gateway ECU*1

  • Option connector (bus buffer ECU)*2

  • Radio receiver assembly

  • Telematics transceiver*3

  • Front steering control ECU*4

  • Yaw rate sensor

  • Headlight leveling ECU assembly

  • Engine stop and start ECU*5

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

WIRING DIAGRAM

B003U4WE05
B003W3QE05
B003ULIE01

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) and 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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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 TO +B IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the K109 No. 1 CAN junction connector.

      A001JNIC67
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b to No. 2 CAN Junction Connector
      *c to Combination Meter Assembly *d to Radio Receiver Assembly
      *e

      to Network Gateway ECU

      (w/ Network Gateway ECU)

      		 *f

      to Option Connector (Bus Buffer ECU)

      (w/o Network Gateway ECU)
      *g to Air Conditioning Amplifier Assembly *h

      to Telematics Transceiver

      (w/ Telematics Transceiver)
      *i to Certification ECU (Smart Key ECU Assembly) *j to Power Steering ECU Assembly
      *k

      to Front Steering Control ECU

      (w/ VGRS System)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K109-1 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 2 CAN junction connector
      K109-11 (CANL) - K9-16 (BAT)
      K109-2 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Combination meter assembly
      K109-12 (CANL) - K9-16 (BAT)
      K109-3 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Radio receiver assembly
      K109-13 (CANL) - K9-16 (BAT)
      K109-4 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      • Option connector (bus buffer ECU)*1

      • Network gateway ECU*2
      K109-14 (CANL) - K9-16 (BAT)
      K109-5 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Air conditioning amplifier assembly
      K109-15 (CANL) - K9-16 (BAT)
      K109-6 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Telematics transceiver*3
      K109-16 (CANL) - K9-16 (BAT)
      K109-7 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Certification ECU (smart key ECU assembly)
      K109-17 (CANL) - K9-16 (BAT)
      K109-9 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Power steering ECU assembly
      K109-19 (CANL) - K9-16 (BAT)
      K109-10 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Front steering control ECU*4
      K109-20 (CANL) - K9-16 (BAT)

      • *1: w/o Network Gateway ECU

      • *2: w/ Network Gateway ECU

      • *3: w/ Telematics Transceiver

      • *4: w/ VGRS System

      Result
      Result Proceed to
      OK A
      NG (No. 2 CAN junction connector main line) B
      NG (ECU or sensor bus line) C

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 3 Click here

    B

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


    1. Reconnect the K109 No. 1 CAN junction connector.

    2. Disconnect the K110 No. 2 CAN junction connector.

      A001JNIC71
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to No. 1 CAN Junction Connector
      *c to Main Body ECU (Multiplex Network Body ECU) *d to ECM
      *e to Headlight Leveling ECU Assembly *f to Airbag Sensor Assembly
      *g to Yaw Rate Sensor *h

      to Engine Stop and Start ECU

      (w/ Stop and Start System)
      *i to DLC3 *j to Steering Sensor
      *k to Skid Control ECU (Brake Actuator Assembly) - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K110-1 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 1 CAN junction connector
      K110-11 (CANL) - K9-16 (BAT)
      K110-2 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Main body ECU (multiplex network body ECU)
      K110-12 (CANL) - K9-16 (BAT)
      K110-3 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher ECM
      K110-13 (CANL) - K9-16 (BAT)
      K110-4 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Headlight leveling ECU assembly
      K110-14 (CANL) - K9-16 (BAT)
      K110-5 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Airbag sensor assembly
      K110-15 (CANL) - K9-16 (BAT)
      K110-6 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Yaw rate sensor
      K110-16 (CANL) - K9-16 (BAT)
      K110-7 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Engine stop and start ECU*
      K110-17 (CANL) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      K110-8 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher DLC3
      K110-18 (CANL) - K9-16 (BAT)
      K110-9 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Steering sensor
      K110-19 (CANL) - K9-16 (BAT)
      K110-10 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Skid control ECU (brake actuator assembly)
      K110-20 (CANL) - K9-16 (BAT)

      • *: w/ Stop and Start System

      Result
      Result Proceed to
      OK A
      NG (No. 1 CAN junction connector main line) B
      NG (ECU or sensor bus line) C
      NG (DLC3 branch line) D

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    B

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

    D

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    C

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


    1. Reconnect all wire harness connectors.

    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.

      Click here

    3. A001KD4C36
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K9-6 (CANH) - K9-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      K9-14 (CANL) - K9-16 (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 BRANCH LINES OR CONNECTOR