Jed,
First we need to clarify what you are referring to as the dimmer switch. If you are referring to the headlight dimmer switch, it has nothing to do with the dash lights. However, if you are referring to the rheostat that is part of the headlight switch that is mounted in the dash, that is what controls the dash light brightness.
If you have 12 volts into the dash light rheostat, what do you have coming out of it? There are about a half a dozen things that that can cause no dash lights. The most common problem is a bad dash ground followed by a defective headlight switch. If you can give me voltage readings at the various locations necessary, we can trouble shoot it here, or you can call me (713-254-4156) and I will walk you through the process.
Gerald