There is nothing connected to my #5 fuse location where the horn wiring is supposed to be attatched. Worse, I can't even see any stray wire in the area that might be loose, etc.

Can somebody who has a decent wiring diagram tell me at least what color wire I'm supposed to be looking for at the fuse block for my horn circuit.?

I had the horn operating some time ago. it figures I might have moved the connector off this terminal and now I can't locate it.

Also, the aftermarket Blaupunkt stereo (which sounds great, BTW) is using a black wire from a ring on the steering column. I believe this would be the horn's ground wire, right?

They brought this black wire over to the radio and nutted it to a thin red wire that goes into the back of the radio. Can't figure this out. But I know it doesn't power the horn circuit, as I touched it to fuse terminal #5 with no success.

Finally, any idea why the radio, yellow wire to fuse #7, would stop working when I pull on the heater fan switch (fuse # 3 or 4, I think)?