Hopefully someone can explain how this relay works?

Well.....this is kinda baffling. Have checked this particular fuse at least a dozen times. Always has continuity. Checked the relay it is supposed to feed...nada. Probed the back of the fuse...one side is hot the other is not. So how does it pass multiple continuity tests but not pass current?

Still has codes. Guessing it is a p0875 (that is what started all this). From what I have been reading the internal harness on the Alison is frequently the cause, when the harness gets old the wick up fluid. I have a harness...