91 headlight switch problems

Hi guys fist of all thanks for the forum its been very helpful but I have a problem with my 91 4x4 ex cab the dim switch for the headlights wont dim or brighten {I have replaced it with a nother with the same results }and the dash lights go very dim when the headlights are on but I blew the fuse to the tail lights and until I replaced it my dash lights stayed bright but I still had no control of the brightness I have spent hours under the dash checking grounds and still nothing I’m lost here any ideas I’m open for suggestions thanks

Hey guys just wanted to let you know I found the problem I had a fuse that was defective I think I couldn’t find a burnt part but after I replaced it every thing worked (wish I would have tried that the first 5 times I went through the fuses it would have saved hours of tracking wires and headaches )