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Home >> Lexus >> 2015 >> IS 250 Base, AWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Can Communication System - Diagnostics - Introduction (07 Of 13) >> Can Communication System >> Diagnosis System [10/2016 - 10/2017] >> Diagnosis System [10/2016 - 10/2017] >> Can Bus Check

Can Bus Check

HINT: 

The ECUs and sensors that are properly connected to the CAN communication system can be displayed using the Techstream.

  1. Using the Techstream, select the CAN Bus Check screen.
    NOTE:
    • It may be possible to select buses that do not have ECUs or sensors from the bus selection pull-down menu. This is not a malfunction. (This occurs when optional devices are not on a sub bus that is monitored by a gateway function equipped ECU.)
    • In the bus selection pull down menu, all buses applicable to the model are displayed (e.g. LIN communication buses are also displayed). Therefore, refer to the wiring diagrams to check the names of sub buses for CAN communication.

      Refer to SYSTEM DIAGRAM [10/2016 - 10/2017]

    HINT: 

    Different connection statuses are indicated by the background color of ECUs and sensors that are displayed.

    EXPLANATION OF CAN BUS CHECK SCREEN

    Bus Type Background Color Connection Status
    Bus White Communication has been normal.
    Yellow Communication stop occurred at least once since the start of the CAN bus check, but communication is currently occurring (unstable communication).
    Red Currently not communicating (either of the following):
    • Not communicating since the start of the CAN bus check
    • Communication occurred at least once since the start of the CAN bus check, but is currently not occurring.
    Not displayed Either of the following:
    • The central gateway ECU (network gateway ECU) has an internal malfunction or cannot communicate with the Techstream.*4
    • No ECUs or sensors are connected to the bus.*5
    Sub bus with a gateway function equipped ECU that does not memorize connected ECUs or sensors*2 White Communication has been normal since the start of the CAN bus check.
    Yellow Communication stop occurred at least once since the start of the CAN bus check, but communication is currently occurring (unstable communication).
    Red Communication occurred at least once since the start of the CAN bus check, but is currently not occurring.
    Not displayed Communication stop has continued since the start of the CAN bus check.*1
    Sub bus with a gateway function equipped ECU that memorizes connected ECUs and sensors*3 White Communication has been normal.
    Yellow Communication stop occurred at least once since the start of the CAN bus check, but communication is currently occurring (unstable communication).
    Red Currently not communicating (either of the following):
    • Not communicating since the start of the CAN bus check
    • Communication occurred at least once since the start of the CAN bus check, but is currently not occurring.
    Not displayed Either of the following:
    • The gateway function equipped ECU cannot communicate with the central gateway ECU (network gateway ECU).*6
    • No ECUs or sensors are connected to the sub bus.*7
    • Gateway function equipped ECUs relay signals between ECUs and sensors connected to different buses.
    • *1: An ECU or sensor is installed to the vehicle but is not displayed on the "Communication Bus Check" screen.
    • *2: The gateway function equipped ECU does not memorize ECUs and sensors connected to its respective sub bus.
    • *3: The gateway function equipped ECU memorizes ECUs and sensors connected to its respective sub bus.
    • *4: When the central gateway ECU (network gateway ECU) has an internal malfunction or cannot communicate with the Techstream, the name of buses, sub buses, ECUs and sensors will not be displayed.
    • *5: When no ECUs or sensors are connected to a bus, the message "There is no system found on the communication Bus." will be displayed.
    • *6: When a gateway function equipped ECU cannot communicate with the central gateway ECU (network gateway ECU), the name of sub buses and ECUs or sensors connected to the sub bus will not be displayed.
    • *7: When no ECUs or sensors are connected to the sub bus, the message "There is no system found on the communication Bus." will be displayed.
    • If there is no communication between the Techstream and the vehicle, or no ECUs or sensors are displayed as connected, check the central gateway ECU (network gateway ECU) and V bus (the bus that connects the DLC3 to the central gateway ECU (network gateway ECU)) for malfunctions.
  2. Observe the connection response screen for approximately 2 minutes to check for a change in connection status of the connected ECUs and sensors.

    HINT: 

    • If an open occurs in one of the lines of a CAN branch (except DLC3), output from the other branch line (the line that is not open) will be unstable and it may interfere with the response (display) of other ECUs and sensors.
    • If the connection status changes during the inspection, repair the open in the branch line of the ECU or sensor that does not respond (is not detected) and then perform the CAN bus check again.
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