Courtesy Light staying on/ Dash lights not working

Dimmer switch(plastic plug) is notorious for shitty shape, all the ones I've seen anyway. Damp floor and dimmer switch, is a recipe for s**t stew. I redid my entire dash harness and went thru about 5 harnesses and everyone had the dimmer switch plug melted.
Electrical is voodoo to me, sorry I ain't much help, other than chk bulkhead connectors and any and ALL connectors.
What you could do is pull 1 fuse at a time and check for the fault after each fuse pull? That might lead u to the problem?