Open in One Side of CAN Branch Line

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: Open in One Side of CAN Branch Line
- Open in One Side of CAN Branch Line

DESCRIPTION

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

HINT
If some ECUs and sensors repeatedly appear and disappear from the "Communication Bus Check" screen, communication between the normal ECUs (sensors) and Techstream 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).





INSPECTION PROCEDURE

NOTICE:
* Turn the ignition switch off before measuring the resistances of CAN bus main wires and CAN bus branch wires.
* After the ignition switch is turned off, check that the key reminder warning system and light remainder warning system are not operating.
* Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches, or the doors. If any doors need to be opened in order to check the connectors, open the doors and leave them open.

HINT
* Operating the ignition switch, any other switches, or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
* 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 CAN NO. 1 BUS BRANCH WIRE

(a) Confirm the systems (ECUs and sensors), which use CAN communication, equipped on the vehicle. System Diagram

(b) Using Techstream, select and perform "Bus Check". Diagnosis System

(c) 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.

(d) Check that the ECUs and sensors, which are connected to the ECUs or sensors that are not displayed on the screen.

(e) Check that the ECUs and sensors, which repeatedly appeared and disappeared from the "Bus Check" screen, are constantly displayed.

NEXT -- GO TO CORRESPONDING COMMUNICATION STOP MODE