1997 horn black button installation.
 

My wife lost her manual to her 97 sl1 and the horn doesnt work now. I need to get it inspected so I bought one of those little black horn buttons but I cant figure out where the relay is. Any tips please?? I tried looking at fuses in one on passenger side but didnt find a blown one. Is there another fuse box?? thanks

The horn fuse is a 10A (Red) minifuse located in the Underhood Junction Box (UHJB) behind the battery.

I believe the Horn relay is right next to the AC/CNTRL Relay. in the UHJB.
Check the underside of the UHJB cover for the layout of what's in there to confirm the above.

To the best of my knowledge, the ground for this circuit runs into the Left forward lamp ground splice pack, along with the left side marker lamp ground, the left Park/Turn/DRL ground, and the Left fog lamp ground.
If you find yourself having to chase down a bad ground, be advised that although the LH and RH splice packs have individual grounds, they also connected to each other (as though they were one continuous splice pack) with two chassis grounds.
My point is everything can still work with one chassis ground in theory as long as the two packs remain interconnected but if both sides lose ground all kinds of stuff will go wrong. No, you did not describe this, but I thought I'd toss it in for future reference.