Multiplex Control System Descriptions

The multiplex Control System has four internal functions:

The system controls the function of these circuits:

Multiplex Communication

To reduce the number of wire harnesses, digital signals are sent via shared multiplex communication lines rather than sending normal electrical signals through individual wires.

Wake-up and Sleep

The multiplex control system has ‘‘wake-up'' and ‘‘sleep'' functions to decrease parasitic draw on the battery when the ignition switch is OFF.


To prevent improper operation, the multiplex control system has a fail-safe function. In the fail-safe mode, the output signal is fixed when any part of the system malfunctions (for example a faulty control unit or communication line).
Each control unit has a hardware fail-safe function that fixes the output signal when there is any CPU malfunction, and a software fail-safe function that ignores the signal from the malfunctioning control unit and allows the system to operate normally.