The lights were burnt out on the vanity mirror lamps of both visors of my 2001 Buick Regal. At first I guessed it had to be a fuse because why would all of them be out at the same time? On closer inspection I could see that the the mirror covers did not close all the way, so that the tiny switch in the upper lefthand corner kept the lights on all the time. I don't know if the computer shuts the lights off eventually; if it doesn't, then this could also be a cause of battery drain.

The lenses pop out with some force. I used a flat blade screwdriver at the top to slightly expand the cavity and pop out the lenses, revealing the tiny light bulbs. I bought new bulbs (BP37) from Napa. The old bulbs are not easy to remove. I had to chip away part of the socket to get enough bulb showing to pry it out with my fingers or with help of a small screwdriver. The new bulbs do not insert easily either; you have to push them in hard until they click in.

The next problem to solve was how to keep the mirror cover closed tightly so that the problem would not recur. I first tried velcro on the inside, but this was not enough force. I then used two rare earth disc magnets (I got mine from china on ebay) and used double sided tape to tape them to the inside of the cover and the base of the mirror. You could also use epoxy, but the magnets that I have are thin, and needed the extra width of the tape. Now the mirror cover clicks shut and keeps the lamps off.