Horn wont shut off

Driving the other day....accidentally bumped the horn and it would not shut off. I pulled over shut truck off and it stopped. hit the horn on purpose to see if it would do it again, same result so i pulled the horn fuse for the time being. Its not a matter of the horn staying depressed on the steering wheel its gotta be something internal or wiring. Anybody got a clue? BTW its an 03 TRD Tacoma. my first thought was a relay but these trucks do not have one for the horn.
__________________

 

Maybe this will help

http://www.justanswer.com/toyota/6a0ev-toyota-tacoma-diagnosing-horn-2002-tacoma.html