rg, thanks. There are a few minor changes I'd like to make to that drawing. However, it has been copied to several different servers, and if I changed the original it would not change any of the copies on the other servers, all of which get a lot more traffic than the copy I put up on my host server.
pamcopete green-lighted this one when I made it a few years ago. His subsequent 7.5 amp ignition fuse recommendation is more of a boast about how little power the Pamco consumes than a safety issue, IMHO. Should a fault occur, a 7-1/2 amp fuse is going to blow a millisecond before a 10 amp fuse does. Fuse sizing is more about protecting the wiring, not the device, while still being big enough so that the device operates.
I buy 10 amp fuses in bulk. It is simpler to stock in the shop, and carry in the tool pouch, 2 sizes of fuse rather than 3.
pa-powerstroke, simplified wiring diagrams are so simple, and your wiring sounds so screwed up, that if you have any ability with wiring and soldering, you should just tear out the whole harness and use it as a source of wire, and do a total re-wire.