Open in One Side of CAN Branch Line

NETWORKING: 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 "CAN Bus Check" screen of the Techstream 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 CAN branch lines.

HINT
If some ECUs and sensors repeatedly appear and disappear from the "CAN 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 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).

WIRING DIAGRAM

INSPECTION PROCEDURE

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

HINT
Operating the engine switch, any switches, or any doors triggers related ECU and sensor communication with the CAN. This communication will cause the resistance value to change.

PROCEDURE

1. CHECK FOR OPEN IN ONE SIDE OF CAN BRANCH WIRE

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

(b) Using the Techstream, select and perform "CAN 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) Disconnect the branch line connectors, which are connected to the ECUs or sensors that are not displayed on the screen, from the CAN junction connector.

Wiring Color

HINT
* Connecting locations of the connectors shown in the above tables are those of a vehicle whose connector locations have never been changed.
* If the connector locations differ from those shown in the above tables, identify each connector according to the color of the bus lines.

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

(f) Perform the communication stop mode check for the ECUs and sensors which correspond to the disconnected branch line connectors Symptom Related Diagnostic Procedures.

NEXT -- GO TO CORRESPONDING COMMUNICATION STOP MODE