Bad dimmer switch....I think

[Tatonks]

Hi all. I'm having a problem with my sister's 2000 Toyota Corolla and I know very very little about wiring. The 3 main back lights in her dash won't work. The rest of the lights work fine. I've checked all of her fuses and none are broken. I replaced the 3 main back light bulbs and hooked the dimmer switch up and lo and behold they worked. After putting everything back together, they don't work. Could she just have a screwy dimmer switch or could it be something else? Thanks for any input.

I was also wondering if I could have a short somewhere that might knocking those bulbs out? Her cd player was stolen awhile back and the wires just sit there dangling.

[Tatonks]

Update: So I went out and bought a multimeter today. I checked the dimmer switch for continuity and my multimeter didn't beep. Does that mean theres a short in the dimmer switch? Also I checked the wiring coming powering the dimmer switch for voltage and didn't get anything? Anyone have any idea what that means?