Horn won't blow , possibly blown fuse. Don't know which fuse works the horn

the fuse blows because somewhere after the fuse , the wire is dead shorting out to ground
check / replace any horn relays

use a multimeter set on ohms resistance and that will tell you that it is shorting out as it will register as a circuit

Check for blown fuse first. If fuse ok, you will have to check for a power and ground supply directly at the horn itself. Possible causes are... defective horn...blown fuse.... defective horn relay....defective horn pad.... defective clock spring..... broken wiring. There is a lot of electrical diagnostics that need to be performed to make this simple horn operate

Should be clear that the problem is in the steering column horn mechanism, but to fix it you will need to remove the air bag.. Are you competent to do that safely?

Mean it has dirty connections on the on the horn, remove the connections and spray some sort of cleaning spray like Wd-40.

possible blown fuse or defected horn

if it was a fuse problem the horn wouldn`t make a noise.it sounds like the horn contacts that touch when you push on the button are not making proper contact each time.if you remove the horn button and look at the contact spots you may see the problem(uneven contact surfaces).if you move/bend the contact surfaces closer to each other of straighten this may help the problem.you may even have a horn that needs to be replaced as you said when it does work it stutters and not blow.the diaphragm in the horn can dry out and not vibrate like it should.try tapping on the horn when someone tries to blow the horn if it stops or gets louder then the diaphragm is no good.you could also check the connection at the horn itself it may have a bad connection due to corrosion and just need cleaning.

possible horn itself is faulty and needs replacing. you will need to locate where the horn is and apply power to the horn from the battery. if the horn sounds then you know that it is a broken wire th=o the horn

Maybe horn became unplugged. Put 12 v power to horn make sure horn works. Put test light on terminal on horn have someone press the horn button, if light comes on and horn does not blow you may need new horn. if light does not come on you may have bad contact at horn button, blown fuse, broken wire, bad horn relay or possibly just a bad ground.

you may need to put a relay in it as the current from the horn may be back feeding up the immobiliser horn circuit and causing a short. Sounds like the immobiiliser has its own source of power seperate from the factory circuit When you press the horn the power goes to the horn and up the immobiliser horn circuit and it blows the fuse.

Find horn, remove wire connector from it, try new fuse, push horn again, if fuse blows, you have short somewhere between, if it doesn't, it's the horn.