CAN COMMUNICATION SYSTEM Check CAN Bus Lines for Short Circuit (LHD Models)

DESCRIPTION

There may be a short circuit between the V bus main lines and/or CAN branch lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CANH) and 14 (CANL) of DLC3 is below 54 Ω.

  • Short in CAN main bus line

  • Short 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 (w/ Network gateway ECU)

  • Option connector (bus buffer ECU) (w/o Network gateway ECU)

  • Radio receiver assembly

  • Front steering control ECU (w/ VGRS system)

  • Yaw rate sensor

  • Headlight leveling ECU assembly (for Single Beam Headlight)

  • Stereo component equalizer assembly (w/ ASC System)

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

WIRING DIAGRAM

B0074H6E02
B0073BOE02
B0075HIE06

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), 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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  • Before replacing the main body ECU (multiplex network body ECU), ECM or certification ECU (smart key ECU assembly), refer to Service Bulletin.

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 IN CAN BUS LINES (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)


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

    2. B007703C32
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the O3 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      O3-29 (CANH) - O3-30 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

  2. CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the O3 combination meter assembly connector.

    2. B0075XRC35
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A71 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A71-14 (CANH) - A71-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  3. CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the A71 ECM connector.

    2. Disconnect the O104 No. 1 CAN junction connector.

      B0073I8C55
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b

      to No. 2 CAN Junction Connector

      (for V Bus)
      *c

      to Combination Meter Assembly

      (for V Bus)

      		 *d

      to Radio Receiver Assembly

      (for V Bus)
      *e

      to Network Gateway ECU

      (w/ Network Gateway ECU)

      (for V Bus)

      		 *f

      to Option Connector (Bus Buffer ECU)

      (w/o Network Gateway ECU)

      (for V Bus)
      *g

      to Air Conditioning Amplifier Assembly

      (for V Bus)

      		 *h

      to Stereo Component Equalizer Assembly

      (w/ ASC System)

      (for V Bus)
      *i

      to Certification ECU (Smart Key ECU Assembly)

      (for V Bus)

      		 *j

      to Power Steering ECU Assembly

      (for V Bus)
      *k

      to Front Steering Control ECU

      (w/ VGRS System)

      (for V Bus)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      O104-1 (CANH) - O104-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction connector
      O104-2 (CANH) - O104-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      O104-3 (CANH) - O104-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio receiver assembly
      O104-4 (CANH) - O104-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher*1 Network gateway ECU*1
      O104-4 (CANH) - O104-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher*2 Option connector (Bus buffer ECU)*2
      O104-5 (CANH) - O104-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      O104-6 (CANH) - O104-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Stereo component equalizer assembly*3
      O104-7 (CANH) - O104-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      O104-9 (CANH) - O104-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      O104-10 (CANH) - O104-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Front steering control ECU*4

      • *1: w/ Network Gateway ECU

      • *2: w/o Network Gateway ECU

      • *3: w/ ASC System

      • *4: w/ VGRS System

      Result
      Result Proceed to
      OK A
      NG (No. 2 CAN junction connector main line) B
      NG (ECU or sensor branch line) C
      NG (Combination meter assembly main line) D

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 5 Click here

    D

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)

    B

  4. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the O104 No. 1 CAN junction connector.

    2. Disconnect the O105 No. 2 CAN junction connector.

      B0073I8C16
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b

      to No. 1 CAN Junction Connector

      (for V Bus)
      *c

      to Main Body ECU (Multiplex Network Body ECU)

      (for V Bus)

      		 *d

      to ECM

      (for V Bus)
      *e

      to Headlight Leveling ECU Assembly

      (for Single Beam Headlight)

      (for V Bus)

      		 *f

      to Airbag Sensor Assembly

      (for V Bus)
      *g

      to Yaw Rate Sensor

      (for V Bus)

      		 *h

      to DLC3

      (for V Bus)
      *i

      to Steering Sensor

      (for V Bus)

      		 *j

      to Skid Control ECU (Brake Actuator Assembly)

      (for V Bus)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      O105-1 (CANH) - O105-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 1 CAN junction connector
      O105-2 (CANH) - O105-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      O105-3 (CANH) - O105-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      O105-4 (CANH) - O105-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Headlight leveling ECU assembly*
      O105-5 (CANH) - O105-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      O105-6 (CANH) - O105-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Yaw rate sensor
      O105-8 (CANH) - O105-18 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher DLC3
      O105-9 (CANH) - O105-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      O105-10 (CANH) - O105-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)

      • *: for Single Beam Headlight

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

    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

    E

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

    C

  5. CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)


    1. Reconnect all wire harness connectors.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

      Click here

    3. B0076CHC86
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K9-6 (CANH) - K9-14 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

      Tech Tips

      If the resistance becomes normal (between 54 and 69 Ω) 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