One problem related to horn assembly has been reported for the 2004 Chevrolet Classic. The most recently reported issues are listed below.
For two years now my doors will lock automatically when I turn the car of and get out. Also the horn will blow for no reason like I have locked the doors. I can't leave my keys in the car because it has locked with keys in the ignition. Recently when I go to start the car I have to jiggle the key to be able to turn it to start. I thought maybe it was the key but I have had new ones made.