CAN COMMUNICATION SYSTEM HOW TO PROCEED WITH TROUBLESHOOTING


  1. IMPORTANT POINTS CONCERNING TROUBLESHOOTING

    CAUTION:

    For vehicles with an airbag system:

    Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

    Note


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

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

    • When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.

    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 GTS.


    1. DTCs indicating a CAN communication malfunction are also stored due to internal or power source-related problems in ECUs or sensors of systems using CAN communication. Therefore, check whether codes indicating internal or power source-related problems in those systems are output together with the CAN communication DTCs.

    2. It is possible to inspect the circuit of the DLC3 CAN branch wire or V1 bus CAN main wire for malfunctions by inspecting the terminals of the DLC3 using SST.

      Note

      It is only possible to inspect CAN branch wires to ECUs (sensors) or the V1 bus from the DLC3.

    3. It is possible to check which ECUs (sensors) are not able to communicate via CAN communication by checking the "Bus Check" function of the GTS (when the DLC3 CAN branch wire and V1 bus CAN main wire are normal).

      Tech Tips


      • When checking "Bus Check", ECUs (sensors) whose CAN branch wire is open or that cannot communicate via CAN communication do not respond to the GTS (they are not displayed on the screen).

      • When checking "Bus Check", if a DTC indicating a CAN communication malfunction is output even though all ECUs (sensors) respond (they are displayed on the screen), use the DTC combination table to determine the suspected trouble area and perform symptom simulation.

    4. For past malfunctions of the V1 bus, the ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.

    5. When an open circuit malfunction is confirmed, before disconnecting the connectors for inspection, check whether the connectors are loose by pushing in the connector case.

    6. When a connector is disconnected, check if the connector terminals or case is damaged, deformed, deteriorated, etc.


    1. VEHICLE BROUGHT TO WORKSHOP


      NEXT

    2. INSPECT BATTERY VOLTAGE

      Standard voltage
      11 to 14 V

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


      NEXT

    3. CHECK FOR DTC*


      1. Using the GTS, check for all DTCs.

        Note


        • If codes indicating internal or power source-related malfunctions of ECUs or sensors are output together with codes indicating that those ECUs or sensors cannot communicate via CAN communication, it is likely that the problem is not in the CAN communication line. Therefore, perform troubleshooting for the DTCs related to the malfunctioning parts first.

        • If a connector of a system which includes a CAN communication line is disconnected when the ignition switch is ON or ACC, CAN communication DTCs will be stored by that system and any related systems.


        NEXT

    4. CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION


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


        NEXT

    5. CHECK CAN BUS LINE


      1. Check for CAN bus line Click here.


        NEXT

    6. CHECK ECUS CONNECTED TO CAN BUS*


      1. Connect the cable to the negative (-) battery terminal.

        Note

        When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.

      2. Select "Bus Check" from "System Select" Click here.

      3. Check the display of the connected ECUs and sensors for a minute.

        Result
        Inspection Result Proceed to
        All ECUs and sensors connected to CAN communication system are displayed on screen (CAN bus circuit currently normal). A
        Single ECU or sensor that should be connected to CAN communication is not displayed (ECU or sensor CAN branch wire open or communication stop). B
        ECU or sensor that should be connected to CAN communication is not displayed or display is intermittent during check (ECU or sensor CAN branch wire open on one side). C

        Note

        ECUs and sensors that are not present will not be displayed. Be careful not to mistake them for communication stop malfunctions.

        Tech Tips

        If the display of an ECU is intermittent during the check, one side of an ECU or sensor CAN branch wire is open (the signal of the ECU is treated as noise, which affects the response and display of the GTS).


        B

        Go to "Problem Symptoms Table" Click here

        C

        Go to "Open in One Side of CAN Branch Line" Click here

        A

    7. CHECK DTC COMBINATION TABLE (V1 BUS CAN BRANCH WIRE OPEN, PAST COMMUNICATION STOP MALFUNCTION)


      1. Based on the combination of output CAN communication system DTCs, determine which ECUs and sensors have a communication stop malfunction Click here.


        NEXT

    8. PERFORM MALFUNCTION SIMULATION TEST (V1 BUS CIRCUIT CAN MAIN WIRE PAST MALFUNCTION)*


      1. Using the GTS, clear all DTCs.

      2. Perform a malfunction simulation test on all harnesses and connectors related to the V1 bus CAN main wire.

      3. Check the DTCs that were output as a result of the malfunction simulation test. Then determine the malfunctioning area.


        NEXT

    9. ADJUST, REPAIR AND REPLACE


      NEXT

    10. CLEAR DTC*


      1. Using the GTS, clear all DTCs.


        NEXT

    11. CONFIRMATION TEST


      NEXT
      END