having an electrical issue on my 99 xj problem is the horn starts blaring when you open any door, also while driving the horn started blaring, then the rear window defogger light was half light with a buzz under the dash went away when you turn the switch on. thought it was a problem with the fuse box pick up a new one from the jy out of a clean 2000 still no change horn blares when you open any door. any help you guys give would help a ton already have a fsm an looking over it now to trace wires

 

Hate to say it. But it sounds like that you have a short and you are going to have to check all the wiring that relates to all the systems that it is affecting. Unfortunately it may be a real pain in the a$$. Hopefully someone else that may have had a similar problem can give you a better area to start looking. Sorry I couldn't be of better help.
BTW, Welcome to the forum. If you find something post it and maybe it will help someone else.
Good Luck!