I have a 94 Ford F-150 (135,000 miles) on which the horn has recently ceased working. I have checked the fuses (related to the horn) both in the in-cab fuse box as well as in the under-the-hood Power Distribution Box and everything seems okay. I have also directly connected the horn to the battery and the horn does work with that connection. I can see no unconnected wires on (or near) the steering column and would appreciate any suggestions on where to start in dealing with this problem.
Another issue, possibly or not related is that the dash air-bag warning light has begun to blink on and off.
Sounds to me like you may have a bad clockspring.
You’ve already checked the basics, so a pro should take over now, in my opinion.
They’re probably related.
A clockspring problem would create both issues.
The signals are not transmitting through so the horn switch can’t and the air bag can’t prove through the system.
BUT
Have an air bag certified tech look at that or your could explode it by messing with it.
As the others have stated already the two issues very well could be related by the clockspring in the steering wheel. The horn circuit is usually activated by the horn switch making a ground connection through the clockspring. If you can find the wire running through the steering column you could verify the trouble is there by manually grounding the wire to see it the horn works that way. Another possible trouble spot is the horn relay.