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

  • Network gateway ECU*1

  • 4WD ECU assembly*2

  • Radio and display receiver assembly*3

  • Headlight leveling ECU assembly*4

  • Certification ECU (smart key ECU assembly)*5

  • No. 3 CAN junction connector

  • No. 4 CAN junction connector

WIRING DIAGRAM

A0027DUE02
A00271NE02
A002AW6E01

CAUTION / NOTICE / HINT

Note


  • Before measuring the resistance of the CAN bus, turn the ignition 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.

  • After turning the ignition 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.

    Click here

  • 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 ignition switch to ON and wait at least 60 seconds, and then drive the vehicle at a speed of 60 km/h (37 mph) or more for 7 seconds 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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  • If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.*


    • *: w/ Smart Entry and Start System

Tech Tips


  • Operating the ignition 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. 4 CAN JUNCTION CONNECTOR)


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

    2. A0027CGC01
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the F22 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F22-17 (CANH) - F22-16 (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. 3 CAN JUNCTION CONNECTOR)


    1. Reconnect the F22 combination meter assembly connector.

    2. A002ACMC02
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A43 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A43-13 (CANH) - A43-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK (for 1AR-FE) A
      OK (for 2GR-FE) B
      NG C

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

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


    1. Reconnect the A43 ECM connector.

    2. Disconnect the F102 No. 3 CAN junction connector.

      A002BUSC33
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to No. 4 CAN Junction Connector
      *c to ECM *d to DLC3
      *e to Steering Sensor *f to Power Steering ECU Assembly
      *g to Main Body ECU (Multiplex Network Body ECU) *h

      to 4WD ECU Assembly

      (for AWD)
      *i

      to Headlight Leveling ECU Assembly

      (w/ Automatic Headlight Beam Level Control System)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F102-1 (CANH) - F102-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 4 CAN junction connector
      F102-2 (CANH) - F102-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      F102-3 (CANH) - F102-13 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher DLC3
      F102-4 (CANH) - F102-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      F102-5 (CANH) - F102-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      F102-6 (CANH) - F102-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      F102-8 (CANH) - F102-18 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher 4WD ECU assembly*1
      F102-9 (CANH) - F102-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Headlight leveling ECU assembly*2

      • *1: for AWD

      • *2: w/ Automatic Headlight Beam Level Control System

      Result
      Result Proceed to
      OK A
      NG (No. 4 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. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 5 Click here

    D

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    E

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

    B

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


    1. Reconnect the F102 No. 3 CAN junction connector.

    2. Disconnect the F103 No. 4 CAN junction connector.

      A002BUSC37
      *a

      Front view of wire harness connector

      (No. 4 CAN Junction Connector)

      		 *b

      to No. 3 CAN Junction Connector

      (for V Bus)
      *c

      to Skid Control ECU (Brake Actuator Assembly)

      (for V Bus)

      		 *d

      to Air Conditioning Amplifier Assembly

      (for V Bus)
      *e

      to Airbag Sensor Assembly

      (for V Bus)

      		 *f

      to Radio and Display Receiver Assembly

      (for Radio and Display Type)

      (for V Bus)
      *g

      to Certification ECU (Smart Key ECU Assembly)

      (w/ Smart Entry and Start System)

      (for V Bus)

      		 *h

      to Combination Meter Assembly

      (for V Bus)
      *i

      to Network Gateway ECU

      (w/ Blind Spot Monitor System or Parking Assist Monitor 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
      F103-1 (CANH) - F103-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 3 CAN junction connector
      F103-2 (CANH) - F103-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      F103-3 (CANH) - F103-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      F103-4 (CANH) - F103-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      F103-6 (CANH) - F103-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio and display receiver assembly*1
      F103-7 (CANH) - F103-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)*2
      F103-8 (CANH) - F103-18 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      F103-10 (CANH) - F103-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Network gateway ECU*3

      • *1: for Radio and Display Type

      • *2: w/ Smart Entry and Start System

      • *3: w/ Blind Spot Monitor System or Parking Assist Monitor System

      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor branch line) C
      NG (DLC3 branch line) D
      NG (Combination meter assembly main line) E

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

    D

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    E

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 4 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. A0028A3C01
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F25-6 (CANH) - F25-14 (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