horn phantom?

[PalmSpringsAreaRealestate]

my 88c4 while sitting in the driveway started honking on its own..a steady blast. i had to bank on the horn/steeringwheel to stop it.
Any ideas why and how to prevent this?
John

 

[mmark2]

I had an 86 that had the same problem, couldn't figure it out so I finally dis-connected my horns.