CAN COMMUNICATION SYSTEM HOW TO PROCEED WITH TROUBLESHOOTING


  1. IMPORTANT POINT CONCERNING TROUBLESHOOTING

    CAUTION:

    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.

    • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.

    • 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 intelligent tester.


    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 branch line or V1 bus main line for malfunctions by inspecting the terminals of the DLC3 using SST.

      Note

      It is only possible to inspect branch lines 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 intelligent tester (when the DLC3 CAN branch wire and V1 bus CAN main wire are normal).

      Tech Tips


      • When checking "Bus Check", ECUs (sensors) whose branch line is open or that cannot communicate via CAN communication do not respond to the intelligent tester (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. The power management control ECU (Power Management1) detects malfunctions in the V2 bus circuit and stores DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.

    6. The main body ECU detects malfunctions in the MS bus circuit and stores DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.

    7. The power management control ECU (Power Management2) detects malfunctions in the power management bus circuit and outputs DTCs depending on the malfunctioning areas. The ECUs (sensors) which cannot communicate via CAN communication can be determined from the combination of CAN communication DTCs that are output.

    8. 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.

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


    1. VEHICLE BROUGHT TO WORKSHOP


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    2. INSPECT BATTERY VOLTAGE

      Standard voltage
      11 to 14 V

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


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    3. CHECK FOR DTC*


      1. Using the intelligent tester, 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 ON or ACC, CAN communication DTCs will be stored by that system and any related systems.


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    4. CHECK INSTALLED SYSTEMS (ECUS AND SENSORS) THAT USE CAN COMMUNICATION


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


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    5. CHECK FOR OPEN CIRCUIT IN DLC3 CAN BRANCH WIRE AND V1 BUS CIRCUIT CAN MAIN WIRE AND CHECK FOR SHORT CIRCUIT (CANH - CANL)


      1. A00OLXXE65
        Text in Illustration
        *a Front view of DLC3

        Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and CAN branch wire.

      2. Measure the resistance of the DLC3.

        Standard Resistance
        Tester Connection Switch Condition Specified Condition Proceed to
        D8-6 (CANH) - D8-14 (CANL) Ignition switch off OK (54 to 69 Ω) A
        D8-6 (CANH) - D8-14 (CANL) Ignition switch off NG (Higher than 69 Ω) B
        D8-6 (CANH) - D8-14 (CANL) Ignition switch off NG (Below 54 Ω) C

        B

        Go to "Open in CAN Main Wire" Click here

        C

        Go to "Short in CAN Bus Lines" Click here

        A

    6. CHECK FOR SHORT TO +B IN CAN V1 BUS (CANH, CANL - BAT)


      1. A00OLXXE67
        Text in Illustration
        *a Front view of DLC3

        Measure the resistance of the DLC3.

        Standard Resistance
        Tester Connection Switch Condition Specified Condition
        D8-6 (CANH) - D8-16 (BAT) Ignition switch off 6 kΩ or higher
        D8-14 (CANL) - D8-16 (BAT) Ignition switch off 6 kΩ or higher

        NG

        Go to "Short to B+ in CAN Bus Line" Click here

        OK

    7. CHECK FOR SHORT TO GND IN CAN V1 BUS (CANH, CANL - CG)


      1. A00OLXXE66
        Text in Illustration
        *a Front view of DLC3

        Measure the resistance of the DLC3.

        Standard Resistance
        Tester Connection Switch Condition Specified Condition
        D8-6 (CANH) - D8-4 (CG) Ignition switch off 200 Ω or higher
        D8-14 (CANL) - D8-4 (CG) Ignition switch off 200 Ω or higher

        NG

        Go to "Short to GND in CAN Bus Line" Click here

        OK

    8. 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
        Result Proceed to
        All ECUs and sensors connected to CAN communication system are displayed on screen (CAN bus circuit currently normal) A
        Except for power management control ECU (Power Management1), no ECUs connected to V2 bus are displayed (V2 bus CAN main wire open or short malfunction) B
        No ECUs connected to V2 bus are displayed (CAN branch wire between power management control ECU and V2 bus circuit is open) C
        Except for power management control ECU (Power Management2), no ECUs connected to power management bus are displayed (power management bus CAN main wire open or short malfunction) D
        No ECUs connected to power management bus are displayed (power management bus circuit is open) E
        Except for main body ECU, no ECUs connected to MS bus are displayed (MS bus CAN main wire open or short malfunction) F
        No ECUs connected to MS bus are displayed (CAN branch wire between main body ECU and MS bus circuit is open) G
        Single ECU or sensor that should be connected to CAN communication is not displayed (ECU or sensor CAN branch wire open or communication stop) H
        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) I

        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 intelligent tester).

        • The power management control ECU checks for proper ECU communication for ECUs that are connected to the V2 bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the power management control ECU for 3 seconds or more will stop being displayed on the intelligent tester.

        • The power management control ECU may be malfunctioning if both of the following occur: 1) all ECUs connected to the V2 bus are not displayed on the intelligent tester; and 2) DTC U1002 (Lost Communication with Gateway Module [Power Management1]) is not output.

        • The power management control ECU checks for proper ECU communication for ECUs that are connected to the power management bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the power management control ECU for 3 seconds or more will stop being displayed on the intelligent tester.

        • The power management control ECU may be malfunctioning if both of the following occur: 1) all ECUs connected to power management bus are not displayed on the intelligent tester; and 2) DTC U1002 (Lost Communication with Gateway Module [Power Management2]) is not output.

        • The main body ECU checks for proper ECU communication for ECUs that are connected to the MS bus and the results are displayed on the intelligent tester. ECUs that stop communicating with the main body ECU for 10 seconds or more will stop being displayed on the intelligent tester.

        • The main body ECU may be malfunctioning if both of the following occur: 1) all ECUs connected to the MS bus are not displayed on the intelligent tester; and 2) DTC U1002 (Lost Communication with Gateway Module [MS Bus]) is not output.


        B

        Go to "DTC U1002" Click here

        C

        Go to "Power Management Control ECU Communication Stop Mode" Click here

        D

        Go to "DTC U1002" Click here

        E

        Go to "Power Management Control ECU Communication Stop Mode" Click here

        F

        Go to "DTC U1002" Click here

        G

        Go to "Main Body ECU Communication Stop Mode" Click here

        H

        Go to "Problem Symptoms Table" Click here

        I

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

        A

    9. CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)*


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

      2. Write down all of the DTCs stored in each ECU.

        Tech Tips


        • If there are communication malfunction DTCs output but the intelligent tester "Bus Check - Communication Bus Check" screen displays all of the ECUs and sensors connected to the CAN system, the communication malfunction DTCs may be past malfunctions that are no longer present.

        • For V1 bus CAN main wire malfunctions, DTCs for related ECUs are also output. Therefore, determine the malfunctioning area based on all of the DTCs that are output.

        • For V2 bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the power management control ECU.

        • For power management bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the power management control ECU.

        • For MS bus malfunctions, DTCs are stored based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the main body ECU.

        Result
        Result Proceed to
        ECU connected to V1 bus outputs communication trouble code A
        Power management control ECU (Power Management1) outputs network malfunction trouble code (U1002) (V2 bus CAN main wire past malfunction) B
        Headlight swivel ECU assembly (AFS ECU) or suspension control ECU outputs network malfunction trouble code (U0073) C
        Power management control ECU (Power Management2) outputs network malfunction trouble code (U1002) (power management bus CAN main wire past malfunction) D
        Main body ECU outputs network malfunction trouble code (U1002) (MS bus CAN main wire past malfunction) E
        Power management control ECU (Power Management1) outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or CAN branch wire connected to V2 bus) F
        Power management control ECU (Power Management2) outputs trouble code other than the network malfunction trouble code (U1002) (past malfunction of ECU or CAN branch wire connected to power management bus) F
        Main body ECU outputs trouble code other than network malfunction trouble code (U1002) (past malfunction of ECU or CAN branch wire connected to MS bus) F

        B

        Go to "DTC U1002" Click here

        C

        Go to "DTC U0073" Click here

        D

        Go to "DTC U1002" Click here

        E

        Go to "DTC U1002" Click here

        F

        Go to "DIAGNOSTIC TROUBLE CODE CHART" Click here

        A

    10. 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.


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


      1. Using the intelligent tester, 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.


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    12. ADJUST, REPAIR AND REPLACE


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    13. CLEAR DTC*


      1. Using the intelligent tester, clear all DTCs.


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    14. CONFIRMATION TEST


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      END