I hate my firewall.....just wrote a suggested diagnositic & it dropped the connection along with my essay, so, a summary version:
In answer to your trim / tilt switch, I guess if you are asking that, you don't have power trim? - it's the switch you might have on the side of the end of your remote throttle / gear lever. Some engines have a "local switch on the side of the cowl as well. If you don't have PT, you wonlt have either......
If you taking the fuse out, and it;s intermittent, poking wires will be a long tedious process & preobably never find it. So, suggestion - wire a bulb on the engine side of the fuse. this will stay lit whenever the fuse is not blown. Go for a burn, you wil lthen see when it;s blowing. IF it's the regulator, it'll probably go above a certian RPM or after a few mins at WOT. Most engines (apart form a few new suprr high tec ones) only really need the battery to turn the starter, so the fuse could blow seconds after it fires, and unless you have a something telling you the voltage you'll not know until you next try to start the engine.
Fuses only go when there's too much current. A visual check would be fto scour all wiring, &look for chaffed or bare wires - that should eliminate a short.