Join Date: Jan 2007
Location: San Diego, Ca, USA
This is not much help, but my 93 experienced the same problem at about 85K on an early morning ride. The next thing I knew the horn energized and then white smoke, followed by an acrid smell. Unable to shut it down until I pulled off the battery connection.
Bottom line, a hot lead some how had gotten frayed and shorted to the horn ground and fried the bundle. Lots of smoke. Once the entire wire harness was replaced all went well for another 20K.
Check for broken insulation on wiring next to the frame. Good hunting.