Abstract: A multiplex communication control unit includes a multiplex communication control circuit and an electric circuit formed in the proximity of the multiplex communication control circuit. Both the multiplex communication control circuit and the electric circuit are formed on a flexible circuit board and are electrically connected with each other via the flexible circuit board.

Abstract: A flexible flat conductor wiring board (5) having required electric circuits is affixedly disposed on an instrument cluster (2) of an instrument panel portion of an automobile so as to be connected to switches and instruments (3A to 3E) that are provided on the instrument cluster (2) in groups so that an electric circuit is formed. Electric functioning components needed to carry out electric control of the switches and instruments are dispersedly provided on the end portions of centrally arranged switches and instruments or provided on the wiring board (5) with the electric control functions being incorporated in the electric circuits of the instrument cluster (2). Switches and instruments (3A to 3E) are provided, and electric circuits for the switches and instruments (3A to 3E) are provided so as to make the instrument cluster (2) an independent electric component. The instrument cluster (2) as an independent electric component is mounted on the instrument panel portion 1 of an automobile.