To what does the black wire on my Momo horn connect? I have the hard part done, the sliding connection to the brass plate, but the black wire came loose.

 

It just needs to be grounded, connect it directly to the adapter, or to one of the bolts that holds down the steering wheel.
Most wheels will come with a horn ring that has a tab on it that you can easily connect it to.

 

OK, there is a yellow wire from the tab on the back of the horn to the horn ring. There is a black wire from the other tab on the back of the horn. The other end of the black wire is loose. There is also a slide connection to the bras ring on the wheel.

If I touch the black wire to the bolt, the horn still does not work. I wonder if a fuse is blown...