Bought a wrecked 06 Mark LT. Front end damaged. All the wiring seemed fine. I replaced rad support and front end sheet metal, along with rad and condensor. Basically everything in front of the fan blade was swapped with a donor 05 F150, including the horns.

Now thats its all together i found the horn to not be working. Found blown horn fuse. Replaced fuse and now the horn works, but barely. It is VERY quiet and isnt a solid noise..... Almost broken like you are tapping the horn 10 times a second.

I dont know the history of the horns or if they worked on the donor truck. My original horns had the connector busted off them in the collision.

Thoughts? I was gonna tryconnecting the horn directly to 12v but its raining outside.... Thought id fish here in the mean time.

 

There may just be a little water inside. I live in New Orleans and it is common for me to traverse water. The first time it happened I replaced them with PIAA after market horns. I kept the same OEM electrical connection to the wire harness but soldered on new connections to the horns. It was pretty easy if you have any experience soldering. Since then I figured out it was the water...now I just remove the horns and spin them 10 or 12 turns until the little drops water fall out.