2000 GP - No rear lights

My cousin called me and says she has no rear lights at all. Tail, brake, turn signals. I did some searching here and found the MFS as a possibility, but her third brake light isn't working either. I haven't had a chance to look at it myself yet, so the third brake light bulb could be out. Could a bad ground cause everything to stop working? Any thoughts?

Dustin

I think I'd eliminate ground problems early-on. You can do that with a voltmeter and a good ground.