Vehicle-mounted wiring system, optical coupler and construction method of vehicle-mounted wiring system

Provided is an in-vehicle wiring system provided with: a plurality of functional units mounted on a vehicle; the optical transmission line is arranged between the functional parts and is used for transmitting optical signals of the functional parts; an electrical wire harness provided in parallel with the optical transmission line in a partial section of the optical transmission line so as to be integrated with the optical transmission line; and an optical coupler that is disposed in the optical transmission line other than the segment and constitutes a part of the optical transmission line. 本发明提供车载布线系统，所述车载布线系统具备：多个功能部，搭载于车辆；光传输线路，布设在所述功能部之间，传输所述功能部的光信号；电气用线束，在所述光传输线路的一部分区段中，以与所述光传输线路成为一体的状态与所述光传输线路并列设置；以及光耦合器，配置在所述区段以外的所述光传输线路中，构成所述光传输线路的一部分。