Well, I don't know how to prove, or disprove if that's why a ground wire was added to the horn area because of that. I don't think even a wiring diagram would help with that. The main thing I wanted to point out is that in 1970 we see cars that have that extra ground wire in that area and 1969 its not there. Assembly manual shows this as well. Im guessing why it was added there and can change the wording to be more clear about that unless we have a way to figure that out better.