So I got a voltage meter tonight and tested the 3 tail light connections and this is what I came up with
Ground (vertical plug) -- Got a -12v reading when connecting to the positive terminal on the battery.
Stop-- Got a -12v reading when connected to the negative battery terminal AND pushing the brake down. (seems right)
Tail-- -12v reading when connected to the negative battery terminal.
I'm not sure if this really helps in diagnosing where the problem is, but it sounds like the ground is the issue right? (long day...can't think)
I'd like to add that I recently reattached the horn, it worked when I reattached it, but now doesn't work. I checked the fuse and it all looks good, could this have anything to do with the tail light issue?