I am no Automotive Electrician but from what you have written it sounds like a new lighting wiring is in the works.
When you use the Dash Dimmer Sw and the Front Running Lights come on it sounds like some wires has melted together.
My thought is to start by taking the Dash apart trace all of the wires from the Dimmer Switch to where ever they go.
Re-run any wires that are either melted, brittle or show any signs of being burnt.
Also check out all of the wiring behind the Dash that has anything to do with the Lights in general, just to be on the safe side.
What happened to make the wiring on the Dimmer Switch burn up ?
Another thought, the Door Switches for the interior lights short out often and I am not sure what the repercussions are from this, mine just didn’t work until replaced but check them too.
4x4, 5sp, Std Cab, Stepside, E4 Red
4” Lift - Coil-Overs, 6” SkyJacker Leafs - No Blocks (Mistake)
31 Spline FX4 Rear Axle, 4.56s and OX Locker, Hurst Shifter w/Optional Stick and "Made by Grev" alignment adapter