The Ring of Fire is an after market addon, would depend on how the PO, or his mechanic decided to run the wiring, and where they wanted to fuse it.
Hopefully, off the main fuse box. I suspect though, you will be doing some wire tracing.
If you had a tester called a "Fox and Hound", it would be a very simple thing to do. The Hound puts a tone signal on the wire you want to follow. The "Fox" sniffs for that tone signal and traces it right to the exact wire you want.
Too expensive for just a once in a while item for a m/c owner though. Nice to have though, used them for years in my business of chasing telephone wiring through closets in big office buildings.
But, if you do it more than once or twice, it might not be too expensive at all. Less than a hundred bucks.
If they are on a seperate switch then more than likely there is an inline fuse somewhere between the ring and the switch , But if they came on with your lights then I would think they were wired direct and use the fuse of the lights ,they could well be shot ,Ciaran