Terry,
Maybe I'll have time to draw out what I think you're describing tonight. What is the car? I *thought* I saw some factory diagrams with 2 fusible links in the system. Maybe one was for the high current side of the horn relay? I don't remember. The point is that it possibly a second one belongs in the system somewhere.

Test your ammeter's internals for low resistance before using it. Also also check for ground short. The PO may have bypassed it out of irrational fear, or for a good reason, like it failed.