Profile: Sumitomo Electric Wiring Systems, Inc. is a manufacturer of wiring harness, terminals and connectors. We also offer relay boxes and junction boxes. Our wire harness is an organized set of wires, terminals & connectors that carries electrical current and signals. Our junction boxes are used to connect several connectors together in one place in a neat, organized and safe method. Our electronic control unit is an electronic device that has the ability to control many different functions on a vehicle such as anti-lock brakes control, keyless entry, delay wipers, door locks and speedometer outputs.