I have an 86 300sl that has a black wire with a yellow stripe next to a brown [ground] wire next to my battery located under the hood on the passenger side. It has power going to it when the key is on. Anybody know what it's for? I also have a battery drain issue, I think. When I connect a test light between the neg. post and the neg. cable not connected to the battery the light is on although not real bright, is that normal? Thanks. Greg.