2001 Mitsubishi Mirage Horn

The contacts on the relay could be arced together, but most commonly the clock spring is coming apart and two wires are touching. That's a wound-up ribbon cable in a plastic housing under the steering wheel. By the time it comes apart that badly, the other circuits should be affected too. Those are for the air bag, and if the cruise control has the switches on the steering wheel, that system won't work either. When the air bag circuit is affected, the red warning light will be on and the computer will have turned the system off.

The first thing is to remove the horn relay. You might be able to pry the cover off and visually inspect the contacts to see if they move freely.