The purple wire is an additional ground. took me a sec to figure out how it connects. so the eyelet is actually grounsing the sendingnujit, and then the other side goes into the suppled connector. we gotta remember, allgough this is a plug and play, there are some parts that are included that are partially "universal" in nature so its not exaclt PnP but its 98% there. lol see what i did there 😉