A wire harness, often referred to as a cable harness or wiring assembly, is a systematic and integrated arrangement of cables within an insulated material. The purpose of the assembly is to transmit signal or electrical power. The motorcycle's wiring harness is responsible for distributing power and connecting all the electrical components on your bike – the lights, turn signals, horn, ignitions system, etc. In its simplest form, motorcycle wiring consists of: the power source (battery). a power or hot wire that runs power from the source.