The lights for the tach, speedo, gas, temp, clock, driver information center, and buttons on the left side of the dash (and maybe others, I haven't looked close enough) will vary in intensity with the headlights on. (I don't know if they vary with the headlights off--are there dash lights with the headlights off?) The lights never go out, they just vary randomly in intensity. They all vary in unison, as if the problem is some central location or part. Is this a common problem and the fault is known?

 

Bringing this back up to the top to see if anyone has an idea as to the problem with the dash lights.

 

Loose connection, probably of a power or ground, somewhere, may be a pig to find.