CAN COMMUNICATION SYSTEM (for LHD) > HOW TO PROCEED WITH TROUBLESHOOTING

for Preparation Click here


NOTICE:
  1. DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0123, U0124, U0126, U0129, B1499, B1207, B1297 and B2326.
  2. Refer to troubleshooting of each system if DTCs regarding the CAN communication system are not output.


1.CHECK AND CLEAR DTCS

    HINT:
    1. CAN communication DTCs are output 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 output.
    2. If a CAN communication wire connector is disconnected with the ignition switch on, the ECUs of the corresponding system and related systems record a DTC.

NEXT


2.CHECK FOR INSTALLED SYSTEMS (ECUS & SENSORS) THAT ADOPT CAN COMMUNICATION
  1. Based on the vehicle equipment and specifications, confirm the systems that use CAN communication (Click here).


NEXT


3.CHECK CAN NO. 1 BUS WIRE
  1. Check the CAN No. 1 bus wire (Click here).

    HINT:
    If the area where an open or short is occurring in a CAN No. 1 bus wire can be determined, refer to the "PROBLEM SYMPTOMS TABLE" (Click here).

NEXT


4.CHECK WITH INTELLIGENT TESTER
  1. Using the intelligent tester, display the "Communication Bus Check" screen (Click here).

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

    Result:

    Symptom
    Proceed to
    All ECUs and sensors connected to the CAN communication system are displayed on the screen.
    (CAN bus circuit is currently normal)
    A
    Some of the ECUs and sensors connected to the CAN communication system are not displayed on the screen.
    (Open in ECU or sensor branch wires, or communication interrupted)
    B*1
    Some of the ECUs and sensors connected to the CAN communication system are not displayed on the screen. During this check, some ECUs and sensors repeatedly appear and disappear from the screen.
    (Open in one side of ECU or sensor branch wires)
    C
    1. All ECUs and sensors except the main body ECU connected to the CAN MS bus are not displayed on the screen.
    2. The main body ECU outputs DTC B2326.
    (Open or short in CAN MS bus main wire)
    D
    All ECUs and sensors connected to the CAN MS bus are not displayed on the screen.
    (Open in main body ECU branch wire)
    E

    NOTICE:
    1. The systems (ECUs, sensors) that adopt CAN communication vary depending on the vehicle and optional equipment. Check which systems (ECUs, sensors) are installed on the vehicle (Click here).
    2. Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in the communication stop mode.
    3. 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 the tester display are affected by signals output from other ECUs which have an open circuit in either of their CAN branch wires.)

    HINT:
    1. *1:See the "DTC CHART" instead of the "COMMUNICATION STOP MODE TABLE", when some of the ECUs connected to the CAN MS bus is not displayed on the screen (Click here).
    2. The ECUs connected to the CAN MS bus are displayed on the screen by the main body ECU.


B.
GO TO "PROBLEM SYMPTOMS TABLE (COMMUNICATION STOP MODE TABLE)"

C.
GO TO "OPEN IN ONE SIDE OF CAN BRANCH WIRE"

D.
GO TO "B2326"

E.
GO TO "MAIN BODY ECU COMMUNICATION STOP MODE"
A


5.RECHECK DTC

    HINT:
    1. Sometimes CAN communication system DTCs are output, but all the 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.
    2. ECUs related to a problem in the CAN No. 1 bus will store DTCs to indicate communication malfunctions. The communication stop mode in the CAN No. 1 bus can be determined by comparing the combination of DTCs that have been set. Refer to the DTC combination table for the CAN No. 1 bus.
    3. The main body ECU will store communication error DTCs when the ECUs connected to the CAN MS bus cannot communicate, or if a network malfunction occurs.

    Result:

    Result
    Proceed to
    An ECU connected to the CAN No. 1 bus outputs a communication error DTC. (A malfunction occurred in the CAN No. 1 bus)
    A
    The main body ECU outputs CAN MS bus DTC B2326. (A malfunction occurred in the CAN MS bus)
    B
    The main body ECU outputs DTCs other than CAN MS bus DTC B2326. (A malfunction occurred in an ECU branch wire connected to the CAN MS bus)
    C


B.
GO TO "B2326"

C.
GO TO "DTC CHART"
A


6.DTC COMBINATION TABLE
  1. Confirm trouble according to the combination of output DTCs regarding the CAN communication system (Click here).

    HINT:
    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 the intelligent tester's "Communication Bus Check" screen.

NEXT


7.CIRCUIT INSPECTION

    NEXT


    8.IDENTIFICATION OF PROBLEM

      NEXT


      9.REPAIR OR REPLACE

        NEXT


        10.CONFIRMATION TEST

          NEXT

          END