The what looks like a factory BA went off last night, only the BA was not set. The horn just started blaring, not intermittant like if the BA was set off. (Some recent rain inside the cab) I did not notice any relay sounds.

I entered the BA code on the door and I think that shut the horn off because I then put the key in and started the truck. If the BA was set and going off I could not start the truck. And the lights were not flashing.

I started the truck and the horn stopped.

This PM the horn will not sound from the wheel button or the BA going off.
The BA seems to be working, when it is set and goes off, lights flash and the truck will not start.
Anyone have a clue what might be wrong?
And for fun what fuse number is for the horn?

Thanks,
BJ