If you haven't already, I would unplug the dimmer control and confirm you have got a good 12V at its input.
If it looks like you have a short, have there been any (theoretically) illuminated electronics that have been pulled and reinstalled, for example, a radio or an illuminated shift knob? I might want to pull those and look for any pinched grey/red wiring.
Sometimes, people wire up aftermarket electronics and wire the wrong thing(s) to ground.
Last edited by johnf; 11-20-2012 at 02:39 PM.