CAN COMMUNICATION SYSTEM HOW TO PROCEED WITH TROUBLESHOOTING

Note


  • DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0123, U0121, U0124, U0126, U0129, U0131, U0140, U0142, U0151, U0155, U0327, U1002 and U1133.

  • Refer to the troubleshooting section for each system if DTCs regarding the CAN communication system are not output.

  • Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.

  • After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not in operation.

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

Tech Tips


  • Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • *: Use the intelligent tester.


  1. VEHICLE BROUGHT TO WORKSHOP


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  2. INSPECT BATTERY VOLTAGE

    Standard Voltage
    11 to 14 V

    Tech Tips

    If the voltage is below 11 V, recharge or replace the battery before proceeding.


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  3. CHECK AND CLEAR DTC*


    1. Using the intelligent tester, perform the ALL DTC check.

      Tech Tips


      • If a CAN communication trouble code that informs that an ECU or sensor has a power malfunction or interior malfunction is causing a communication stop, the problem may not be in the communication line. There is a high possibility that the ECU or sensor has a signal transmission failure. Therefore, first troubleshoot any DTCs related to the ECU or sensor.

      • When CAN communication related connectors are disconnected with the ignition switch ON or ACC, the ECU related to the connector and ECUs of related systems will store a CAN communication DTC.


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  4. CHECK CAN BUS LINE

    Tech Tips

    Check the CAN bus line Click here.


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  5. CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT ADOPT CAN COMMUNICATION


    1. Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Click here.


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  6. CHECK CAN COMMUNICATION USING INTELLIGENT TESTER*


    1. Select "Communication Bus Check" Click here.

      Result
      Result Proceed to
      All ECUs and sensors connected to CAN communication system displayed on screen. A

      • All ECUs except the power management control ECU*1 connected to the power management bus are not displayed on the screen.

      • The power management control ECU*1 outputs DTC U1002.

      		 B
      One of the ECUs and sensors connected to the CAN communication system is not displayed on the screen. C
      Some ECUs and sensors repeatedly appear and disappear on the screen during this check. D

      Note


      • The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and option settings. Check which systems (ECUs and sensors) are installed on the vehicle Click here.

      • Non-installed ECUs or sensors are not displayed. Do not mistake them for being in communication stop mode.

      • The ECUs and sensors that repeatedly appear and disappear from on screen during this check are considered normal. (The response to the intelligent tester and the tester display are affected by signals output from other ECUs which have an open circuit in either of their CAN bus branch wires.)

      Tech Tips

      The ECUs connected to the power management bus are displayed on the screen by the power management control ECU*1.

      *1: for 1KR-FE and 1NR-FE with Entry and Start System


      B

      GO TO U1002 Click here

      C

      GO TO COMMUNICATION STOP MODE Click here

      D

      GO TO OPEN IN ONE SIDE OF CAN BRANCH WIRE Click here

      A

  7. RECHECK DTC*

    Tech Tips


    • Sometimes CAN communication system DTCs are output, but all ECUs and sensors connected to the CAN communication system are displayed on the intelligent tester. In this case, previous or history DTCs may indicate the cause of the problem.

    • ECUs related to a problem in the CAN bus will store DTCs to indicate communication malfunctions. The communication stop mode in the CAN bus can be determined by comparing the combination of DTCs that have been set. Refer to DTC Combination Table for the CAN bus.

    Result
    Result Proceed to
    Communication error DTCs other than the codes output from the power management control ECU*1 is output. A
    The power management control ECU*1 outputs DTC U1002. B

    *1: for 1KR-FE and 1NR-FE with Entry and Start System


    B

    GO TO U1002 Click here

    A

  8. DTC COMBINATION TABLE


    1. Confirm trouble according to the combination of output DTCs regarding the CAN communication system Click here.

      Tech Tips

      Previous CAN communication system DTCs may be the cause if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed the "Communication Bus Check" of the intelligent tester.


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  9. INSPECT CIRCUIT


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  10. IDENTIFICATION OF PROBLEM


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  11. REPAIR OR REPLACE


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  12. PERFORM CONFIRMATION TEST


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    END