Information Bus: Description and Operation

SYSTEM OUTLINE

MULTIPLEX COMMUNICATION SYSTEM
The system is comprised of the communication modes of the body ECU No.1, body ECU No.2, driver door ECU, front passenger door ECU, rear door LH ECU, rear door RH ECU, engine control module, combination meter, A/C control assembly, tilt and telescopic ECU, power seat ECU, moon roof control ECU, center airbag sensor assembly and gateway ECU. The body electrical systems are controlled by a serial communication in which each ECU is linked to another via a single communication line. This system is also equipped with a self diagnosis function.




The table shows the systems under the control of the MPX communication system and related ECUs (Communication nodes).

COMMUNICATION OUTLINE
Communication is implemented among the body No.1, No.2, driver door, front passenger door, rear door LH, rear door RH, center airbag sensor assembly, gateway tilt and telescopic, A/C control assembly, moon roof, power seat, engine control ECUs.

Upon receiving signals from applicable switches such as the door lock control switch or door courtesy light switch, each ECU determines the conditions of the switches as well as of the doors, and after converting this information into digital signals, outputs them to other ECUs via serial data communication. The ECU that receives these digital signals determines the conditions of the switches and doors so that it can implement various controls such as to activate a door lock motor.

However, if there are no changes in the input signals because no doors were opened and no switches were used within 30 seconds, the body ECU interrupts the communication to save electricity. Following this interruption, any changes in the input signals will cause the communication to resume.