CAN COMMUNICATION SYSTEM HOW TO PROCEED WITH TROUBLESHOOTING

Note


  • DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0110, U0122, U0123, U0124, U0126, U0129, U0131, U0140, U0142, U0146, U0151, U0155, U0164, U0293, U0327, U0424, U1002, U1107, and U1133.

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

Tech Tips

*: Use the intelligent tester.


  1. VEHICLE BROUGHT TO WORKSHOP


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  2. CUSTOMER PROBLEM ANALYSIS


    1. Interview the customer and confirm the problem.


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  3. CHECK BATTERY

    Standard Voltage
    11 to 14 V

    Tech Tips

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


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  4. CHECK AND CLEAR DTCS*

    Tech Tips


    • CAN communication DTCs are stored when there is an open or short in any of the communication wires. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU or the sensor itself also cause these DTCs to be stored.

    • If a CAN communication wire connector is disconnected with the power switch on (IG), the ECUs of the corresponding system and related systems store a DTC.


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  5. CHECK DLC3 BRANCH WIRE AND V1 BUS MAIN WIRE (CANH - CANL)

    Note


    • Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.

    • Turn the power switch off before inspecting CAN bus wires for a ground short.

    • After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.

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

    Tech Tips


    • Operating the power 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.


    1. A003UFPE21

      Turn the power switch off.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      E11-6 (CANH) - E11-14 (CANL) Power switch off 54 to 69 Ω
      Text in Illustration
      *1 DLC3
      Result
      Result Proceed to
      OK A
      NG (70 Ω or higher) for LHD B
      NG (70 Ω or higher) for RHD C
      NG (Below 54 Ω) for LHD D
      NG (Below 54 Ω) for RHD E

      B

      GO TO OPEN IN CAN MAIN BUS WIRE (LHD Models) Click here

      C

      GO TO OPEN IN CAN MAIN BUS WIRE (RHD Models) Click here

      D

      GO TO SHORT IN CAN BUS WIRES (LHD Models) Click here

      E

      GO TO SHORT IN CAN BUS WIRES (RHD Models) Click here

      A

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


    1. A003UFPE22

      Turn the power switch off.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      E11-6 (CANH) - E11-4 (CG) Power switch off 200 Ω or higher
      E11-14 (CANL) - E11-4 (CG) Power switch off 200 Ω or higher
      Text in Illustration
      *1 DLC3
      Result
      Result Proceed to
      OK A
      NG (LHD) B
      NG (RHD) C

      B

      GO TO SHORT TO GND IN CAN BUS WIRE (LHD Models) Click here

      C

      GO TO SHORT TO GND IN CAN BUS WIRE (RHD Models) Click here

      A

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


    1. A003UFPE23

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E11-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      E11-14 (CANL) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      Text in Illustration
      *1 DLC3
      Result
      Result Proceed to
      OK A
      NG (LHD) B
      NG (RHD) C

      B

      GO TO SHORT TO +B IN CAN BUS WIRE (LHD Models) Click here

      C

      GO TO SHORT TO +B IN CAN BUS WIRE (RHD Models) Click here

      A

  8. 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.


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  9. CHECK ECUS CONNECTED TO CAN BUS*


    1. Select "Bus Check" from the "System Select" screen on the intelligent tester.

    2. Select "Communication Bus Check" from the "Bus Check" screen.

    3. Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.

      Result
      Result Proceed to

      All ECUs and sensors connected to the CAN communication system are displayed on the screen.

      (CAN bus circuit is currently normal.)

      		 A

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

      • The power management control ECU (power management2) outputs DTC U1002.

      (Open or short in power management bus main wires.)

      		 B

      All ECUs connected to the power management bus are not displayed on the screen.

      (Open in power management control ECU branch wires or power management control ECU malfunction.)

      		 C

      One of the ECUs and sensors connected to the V1 bus is not displayed on the screen.

      (Open in ECU or sensor branch wires, or communication interrupted.)

      		 D

      One of the ECUs and sensors connected to the power management bus is not displayed on the screen.

      (Open in ECU or sensor branch wires, or communication interrupted.)

      		 E

      Some ECUs and sensors repeatedly appear and disappear on the screen during this check.

      (Open in one side of ECU or sensor branch wires.)

      		 F

      Note


      • The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and optional equipment. Check which systems (ECUs and sensors) are installed on the vehicle.

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

      • The ECUs and sensors that repeatedly appear and disappear from the screen during this check are considered normal. (The response to the intelligent tester and its 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.


      B

      GO TO U1002 (POWER MANAGEMENT2) Click here

      C

      GO TO POWER MANAGEMENT CONTROL ECU COMMUNICATION STOP MODE Click here

      D

      GO TO COMMUNICATION STOP MODE TABLE Click here

      E

      GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

      F

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

      A

  10. 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. 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.

    • The power management control ECU will store communication error DTCs when the ECUs connected to the power management bus cannot communicate, or if a network malfunction occurs.

    Result
    Result Proceed to

    Communication error DTCs other than the codes output from the power management control ECU are output.

    (A malfunction occurred in the V1 bus.)

    		 A

    The power management control ECU (Power Management2) outputs DTC 1002.

    (A malfunction occurred in the power management bus.)

    		 B

    The power management ECU outputs DTCs other than DTC 1002.

    (A malfunction occurred in an ECU branch wire connected to the power management bus.)

    		 C

    B

    GO TO U1002 (POWER MANAGEMENT2) Click here

    C

    GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

    A

  11. DTC COMBINATION TABLE


    1. Confirm the problem according to the combination of output DTCs regarding the CAN communication system.

      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 on "CAN Bus Check" of the intelligent tester.


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  12. CIRCUIT INSPECTION


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  13. IDENTIFICATION OF PROBLEM


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  14. REPAIR OR REPLACEMENT


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  15. CONFIRMATION TEST*


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    END