Description of On-Board Diagnostics

MULTIPLEX COMMUNICATION SYSTEM (BEAN)

The BEAN communication line consists of 2 systems:
One is a system with a loop-shaped line that the back door ECU is united with the body ECU present in the center of the line. Another is a system that the body ECU and the theft deterrent ECU are connected alone.

Since the line for the back door ECU is loop-shaped, the communication can be maintained by the line that is not open even if part of the line become open for some reason. In the case that there is a short-circuit (bus-down) in the line, however, all the BEAN communication becomes impossible in the system and some DTCs are output.

HINT:
- When bus-down occurs, communication from the related ECU stops. Therefore, DTC cannot be output, so perform a DTC (SAE code) inspection using the hand-held tester.
- The theft deterrent ECU and the back door ECU have a single communication line. Therefore, if the line has a short-circuit (bus-down), the BEAN communication will be impossible and DTCs will not be output, either.