Not a real problem with these but the contacts do get dirty. Soda, Beer etc....
First. Check and see if the horns are getting voltage. Meter or even a test light.
Second. Do the horns even work. Make a 12v. jumper and go direct to them.
Third: Disable the air bag. Usually pull the fuse or sometimes there is a yellow connector under the steering column. This is well marked. But follow any directions the owners manual say's.
Fourth. Remove the steering wheel pad and use a small jumper and touch the two wires from the contact side.
If the horns do work its in the contacts. If they don't let me know and I have the Mitchell on Demand at work and will see how complicated this is...
Most cars now use a horn relay thats more a circuit board than the older stuff but you will not here a click from it like in the past.
Hope this helps. This is a generic step as going from the top of my head!!
Keep us posted.