CAN COMMUNICATION SYSTEM(for LHD) Open in One Side of CAN 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 one pair of CAN branch wire.

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 its CAN branch wires. In this case, the CAN branch wires 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 its CAN branch wires).

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

  • Blind spot monitor sensor LH*1

  • Brake actuator assembly (skid control ECU)

  • Power steering ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Lane departure warning camera*2

  • Air conditioning amplifier assembly

  • Engine stop and start ECU*3

  • Radio and display receiver assembly*4

  • Navigation ECU sub-assembly*5

  • 4WD ECU assembly*6

  • Certification ECU (smart key ECU assembly)*7

  • Spiral with sensor cable sub-assembly (steering angle sensor)*8

  • Airbag sensor assembly
*1: w/ Blind Spot Monitor System
*2: w/ Lane Departure Alert System
*3: w/ Stop and Start System
*4: for Radio and Display Type
*5: for Navigation Receiver Type
*6: for 4WD/AWD
*7: w/ Entry and Start System
*8: w/ Vehicle Stability Control 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

  • Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • 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

Tech Tips


  • Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • Perform the following inspection for the ECUs (sensors) which are not displayed on the GTS. If a malfunction cannot be identified, perform the following inspections for the ECUs (sensors) connected to the CAN communication system.

  • Do not remove the combination meter assembly and ECM, as they are the end parts of the circuit. If removed, CAN communication will not be possible.

  • The open circuit confirmation of the combination meter assembly, ECM and main wire is performed in the Check CAN Bus Line procedure of "How to Proceed with Troubleshooting". This inspection only has procedures for checking for an open circuit on one side of the CAN branch wire.

  • 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 V BUS CAN BRANCH WIRE


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

      Click here

    2. Using the GTS, select and perform "CAN Bus Check"

      Click here


      CAN Bus Check

    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