1997 Cadillac STS Horn

The horns are powered from the seats circuit breaker. If you have power seat functions, that is good. The relay is in the underhood relay center, under the flap at the left strut tower. You can swap that relay with another(fuel pump or a/c comp) and see if it works. The horn switch(part of the airbag) supplies the ground. Power goes up the column, through a slip ring contact to the switch, and a ground lead attaches to the steering wheel and grounds through the column. Either you have a bad relay, open contact at the slip ring, an open ground under the airbag, a faulty switch(airbag), a faulty horn ground(G100 near the battery), or faulty horns. Depending on the option you could have a four note horn, or two. With a four note horn, I would doubt they all are bad. But with a two note, one could have been bad, and the other finally went, just a possibility.