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.
The horn fuse is the same as the stop lamp fuse
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.
Your horn is in back of the radiator grill (Grill in front of the car)
The owners manual should have a fuse box diagram. If you don't have one, try MOTORLIT.COM
in the stearing wheel
check the fuse to make sure it has not blown out
behind the plastic grill on the front.
The horn for the 1990 Mazda Protege is located near the right turn signal at the front of the car. To the left of the radiator when your looking at the engine with the hood up.
It is in front of the radiator and the horn itself can be bad.
If you open the fuse panel (to the left under the steering wheel), is is the upper most left fuse. It's a yellow one (20), but it also controls your stop lights so be careful. Hope that helps!
Have your Mazda dealer parts department print out a picture of the relays location for you. They will do this if you ask them.
It is behind the front Grill