Section 893 (Multiplex Communication System - Diagnosis): Pre-Check

1. BEAN communication line consists of 2 systems:

   One is a system with a loop-shaped line where the door system ECUs are united with the body ECU present in the center of the line. Another is a system where the body ECU and theft warning ECU (theft deterrent ECU) are connected alone.

   Since the line for the door ECU is loop-shaped, the communication can be kept by the line that is not open even if a part of the line becomes open for some reasons. In case that the line becomes short (bus-down) for some reasons, however, all the BEAN communication will be impossible and some DTC will be output.

HINT:

• When bus-down occurs, communication from the related ECU will stop. Therefore, outputs of DTC will be impossible, so perform a DTC (SAE code) inspection with the OBD II scan tool or hand-held tester.
• Security ECU has a single communication line. Therefore, if the line becomes short (bus-down), the BEAN communication will not be impossible and DTCs will not be output multiply, either.

1. Inspect the battery voltage.

   Standard: 10-14V 

2. Inspect the diagnosis monitor code output.
   1. Perform a diagnosis code check of the gateway ECU by connecting the OBD II scan tool or hand-held tester to the DLC3 and turning the ignition switch ON.

      HINT:

      When diagnosis code check can not be performed, check if the display shows communication error (change the new diagnostic system and the operations when an error occurred.)

   2. When the display shows diagnostic codes of the ECU unconnected and the communication bus defective, perform the inspection depending on the troubleshooting.

      HINT:

      When other diagnostic code is output, refer to the diagnostic code table and check the applicable information.