CAN COMMUNICATION SYSTEM Open in One Side of Bus 1 Branch Line

DESCRIPTION

If an ECU or sensor is not displayed on the CAN Bus Check screen of the GTS and some ECUs and sensors repeatedly appear and disappear from the screen when the CAN main bus lines are normal (there is no open, short, short to +B or short to GND in the main bus lines), there may be an open circuit in either of the lines in a CAN branch.

Tech Tips

If some ECUs and sensors repeatedly appear and disappear from the CAN Bus Check screen, communication between the normal ECUs (sensors) and the GTS may be affected by the incomplete signals that are output from the ECU that has an open circuit in either of the lines in its CAN branch. In this case, the CAN branch lines for the ECUs and sensors that repeatedly appear and disappear from the screen are normal and the ECU that is not displayed on the screen may be the main cause of the problem (this ECU may have an open circuit in either of the lines in its CAN branch).

Symptom Trouble Area
2 or more ECUs and/or sensors do not appear on the GTS CAN Bus Check screen.

One side of CAN branch line is open, or output signals are incomplete.


  • Clearance warning ECU assembly (w/ LEXUS Parking Assist-sensor System)

  • Parking assist ECU (w/ Panoramic View Monitor System)

  • Forward recognition camera (w/ Lexus Safety System +)

  • Millimeter wave radar sensor assembly (w/ Lexus Safety System +)

  • Front television camera assembly (w/ Panoramic View Monitor System)

  • Driving support ECU assembly (w/ Lexus Safety System +)

  • Side camera RH (outer rear view mirror assembly RH) (w/ Panoramic View Monitor System)

  • Side camera LH (outer rear view mirror assembly LH) (w/ Panoramic View Monitor System)

  • Rear television camera assembly (w/ Panoramic View Monitor System or Parking Assist Monitor System w/o Parallel Parking Assist Function)

  • Blind spot monitor sensor LH (w/ Blind Spot Monitor System)

CAUTION / NOTICE / HINT

Note


  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

    Click here

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • DTC check procedure: Turn the engine switch on (IG), wait for at least 20 seconds, and then drive the vehicle at a speed of 36 km/h (22 mph) or more for 32 seconds or more.

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed.

    Click here

Tech Tips

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.

PROCEDURE


  1. CHECK FOR OPEN IN ONE SIDE OF BUS 1 BRANCH LINE


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

      Click here

    2. Using the GTS, select and perform the CAN bus check.

      Click here

    3. Observe the screen for approximately 2 minutes to check the ECUs and sensors that are not displayed on the screen and also those that repeatedly appear and disappear from the screen.

    4. Check the applicable communication stop mode for the ECU or sensor that is not displayed on the screen.

      Result
      Proceed to
      NEXT

    NEXT

    GO TO CORRESPONDING COMMUNICATION STOP MODE Click here