CAN COMMUNICATION SYSTEM > Open in One Side of CAN Branch Line

for Preparation Click here


DESCRIPTION

If an ECU or sensor is not displayed on the "Communication Bus Check" screen of the intelligent tester 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 the CAN branch lines.

HINT:
If some ECUs and sensors repeatedly appear and disappear from the "Communication Bus Check" screen, communication between the normal ECUs (sensors) and the intelligent tester may be affected by the incomplete signals that are output from the ECU that has an open circuit in either of 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 its CAN branch lines).


Symptom
Trouble Area
2 or more ECUs and/or sensors do not appear on the intelligent tester "Communication Bus Check" screen.
One side of CAN branch line is open, or output signals are incomplete.
  1. Power management control ECU
  2. ECM
  3. Main body ECU (Multiplex network body ECU)
  4. Combination meter assembly
  5. Skid control ECU (Brake booster with master cylinder assembly)
  6. Steering angle sensor (Spiral cable with sensor sub-assembly)
  7. Yaw rate and acceleration sensor
  8. Power steering ECU assembly
  9. Airbag sensor assembly
  10. Transmission control ECU assembly
  11. Certification ECU (Smart key ECU assembly)
  12. Navigation ECU (Display and navigation module display)*1
  13. Navigation ECU (Navigation computer sub-assembly)*2
*1: w/ Navigation system (for DVD)
*2: w/ Navigation system (for HDD)

INSPECTION PROCEDURE

HINT:
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.

1.CHECK FOR OPEN IN ONE SIDE OF V1 BUS BRANCH LINE

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

  1. Using the intelligent tester, select and perform "Communication Bus Check" (Click here).

  1. Observe the screen for approximately 1 minute to check the ECUs and sensors that are not displayed on the screen and also those that repeatedly appear and disappear from the screen.

  1. 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)