High resistance somewhere. Probably just one or two strands of wire left conducting anything. You can try and trace the existing wire, or, just run a new one, and splice it in at the ends.

Have you tried a different relay there yet? Sometimes, relays can be the source of the issue.

 

I have tried a new relay, sadly it wasn’t the issue. I’ve concluded the same as you, must be a good break in the wire somewhere creating resistance to lose most of my 12 volts. Think I’ll have a look at the wiring and try to find a spot I can splice, don’t have any good wire on hand to run a new one. Thanks for the help and I will update with the fix for my situation