If there is anything left of the original harness, you will find it tied to the frame under the gas tank. it would be nice to work with something original if you can, otherwise you could be reinventing the wheel. I would recommend you also hook up a brake light along with a tail light. That's one of those lights that makes me nervous. If it isn't working, you could have someone slam into the back of your bike. These are almost more important than signals. You should also include fuses or a fuse box of some sort in you install. Not to say you can't do it yourself, but if you are unfamiliar with electrics/electronics you may want to find someone with that experience to help. It could make it go faster. But if you want to do it yourself, you can get lots of advice here. First thing: is get a multimeter.