I think this should be solvable without a meter. . .

With the headlight switch in the "Headlight" position;
1) Headlights work
2) Brake lights work
3) tail lights do not work
4) Instrument lighting does not work

With the headlight switch in the parking light position;
Everything, including tail and instrument lights and dimmer, works as advertised.

I know the headlight switch is not the problem (replaced), even though from the wiring diagrams I have that seemed the only common point for the failed items.

Ideas? Do the instrument and tail lights get power from a different source when headlight switch is moved from "parking" to "headlight", and is that a different power source than for the headlights?

Thanks!