CAN COMMUNICATION SYSTEM 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 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 lines. 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.


  • AFS ECU*1

  • Main body ECU (Multiplex network body ECU)

  • Brake actuator assembly

  • Steering sensor

  • Clearance warning ECU assembly*2

  • Power steering ECU with motor assembly

  • Airbag sensor assembly

  • Air conditioning amplifier assembly

  • Smart key ECU assembly (Certification ECU)*3

  • Navigation receiver assembly*4

  • Radio and display receiver assembly*5

  • Network gateway ECU*6

  • Inner rear view mirror assembly*7

  • Telematics transceiver*8

*1: w/ AFS

*2: w/ Toyota Parking Assist-sensor System

*3: w/ Smart Entry and Start System

*4: for Navigation Receiver Type

*5: for Radio and Display Type

*6: w/ Network Gateway ECU

*7: w/ Automatic High Beam System

*8: w/ Telematics Transceiver

INSPECTION PROCEDURE

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 ignition switch to ON, wait at least 31 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 5 minutes. Check that the warning light remains off after turning off following the initial light check.

  • After the repair, perform 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 V BUS 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.


    NEXT

    GO TO CORRESPONDING COMMUNICATION STOP MODE Click here