Electric Horn and Air Horn

[Memphisdoug]

I've asked this question before but never got an answer. One of my trucks has both an electric horn and an air horn. Only the air horn is wired now and works fine. Is the electric horn supposed to be wired in parallel to the air horn so they both sound at the same time or is it supposed to have its own button somewhere?

 

[gunboy1656]

I would assume the it was update from electric to the air system, and left the electric there to cover the opening that would be left.