The horn fuse is the same as the stop lamp fuse
The fuse for the horn should be on the drivers side underneath the dash. There is a diagram on it that shows the horn fuse.
Where can you find a diagram for fuse panel in a 2003 Mazda Miata?
check the fuse
Then you have a short in the wiring, the horn button is defective, or the horn itself is defective.
diagram of fuse box of 2003 mazda b3000
Fuse? check your fuse box for the fuse indicated "horn" remove and replace if neccessary. if fuse is not the problem, check wiring to horn under the hood in the engine compartment.
The horn relay should be located on the fuse box under the dash. most of the horn relay's that I have seen are a big white fuse, if it isn't on the fuse box, check near the horn.
It is important to know where the parts are within a car. The horn relay in a 1993 Mazda Protege is found in the cars fuse box.
Horn Fuse # 14 ( 20 amp) in the fuse panel on the passenger side. Be sure and check fuse. Exchange with another 20 amp fuse and try horn if horn still does not work then it is the horn relay located under the hood fuse panel.
check the fuse to make sure it has not blown out
look in your fuse panel for a fuse labeled HORN..pull it out and see if it is blown (broken)