Bill, on my starter there is the heavy lead from bat to heavy post on starter sol. Also a purple (colour likely irrelevant) that goes to harness to ign switch sol. With the heavy wire is a 10 gauge wire......trying to check my book where that goes. I think it goes to 70 amp fuse then to fuse panel?

So what you are saying is disconnect purple and see if "voltage drain" with everything off continues? Thanks. Doug