Dash lights go out

Believe it or not, "no" I don't.

You are saying you changed the switch and still have the problem? What condition is the HL switch connector in?

The HL switch gets power from TWO sources. ONLY the HL gets power from the ammeter splice, NOT FUSED

The power for dash, as well as tail and park comes FROM the tail and park fuse. MAKE SURE the park lights are actually still working.

Through the switch, through the dimmer control, and OUT TO THE instrument fuse. From that fuse, off to all the dimmer controlled lamps

So with the park lights on, and working, check for power at the inst. fuse, on both ends. Then turn on the HL and recheck there at the fuse. As I said, also recheck that the tail / park are actually staying on / working