A common failure on a 1987-89 Mustang is the contacts on a factory horn pad wear thin causing horn failure. Over time the foam insulation between the copper contacts under the horn pad becomes brittle and tears or disintegrates. This allows the copper contacts to touch, sometimes, even when the horn button is not being pressed. Does your horn honk at times when you are not even in the car, or not honk at all? If so, this handy Mustang horn pad replacement is what you need. This kit (LRS-13805ARP) includes a new Mustang foam horn contact pad, a scotch-brite pad and some instructions, however we made a short video that describes the whole process.
It is a simple process to remove the factory horn pad from the steering wheel and then peel off the rubber pad exposing the copper plates. Using a screwdriver, gently pry off the upper contacts and remove what is left of the factory foam insulator. Use the scotch-brite pad to the clean the contacts and replace with the new foam insulator. Add the upper copper contact back on and then wrap the rubber horn pad back over the horn plate and reattach to the steering wheel. Check out this video on replacing your Mustang horn button repair pad, it explains it all.