Last night when I got the 73 2.0 home for the first time, I tested the lights, Blinkers, hazzards dash lights and such. They all worked, Today I washed the car, and cleaned the interior. when I went to show the guages to a friend with the lights on.... They didnt work. I turned the light knob both ways and still nothing. Is there a fuse? what is the steps to begin checking for the bug ?

check fuses. rotate them, even if they look ok. fiddle with the lightswitch ...

also, did you get anywhere near the small square black "defroster" thing on top of the center tunnel, in front of the shifter?
the light inside is hooked up to the same circuit as your gauge lights and the 12V for it is only about 1mm away from the metal of the center tunnel.
common cause for a short-circuit, and nearly impossible to diagnose if you don't know ...
Andy

ahhh I cleaned the whole car, Including the center console, and all around the guages and the Little Black Box. I will fiddle with that and see what results I get. Thank you.