When that fuse is blown, I can't shift the auto transmission away from park. Can anyone tell me why using the horn does this? In the past, I did not have problems with the horn. Thanks.

 

you have an exposed wire somewhere
i had the same problem 2 months ago, my spoiler taillight wire were exposed and touching metal and everytime i honked/hit the break, my fuse would blow.

 

how should i go about determining where the wire is exposed

 

this is if fuse only blows when you push horn buttin...... the brake and horn system share the same fuse so if it blows, the brake switch cannot activate the shift interlock solenoid thus you cannot get car out of park ,, it fuse blows when you apply horn ,find where the horns are and unplug them i have seen horn short internally , once disconnected put a fuse and push on the horn button it won't toot but if fuse does not blow the horns are faulty if it still blows fuse you got a short on the horn system ,,

 

you need a "Horn broken, watch for finger" bumper sticker

definatly a short somewhere, you'll hae to use a multimeter and start tracing wires. no other way to find it.