All the buttons on 93+ NX in the center stack as well as all B13 Sentra's should light up. If they dont a bulb is burnt out. I know the part # you can get form radio shack to fix this yourself for a few bucks.. A few years back I got a little OCD and wanted to fix all my lights..
[INDENT]Radio Shack p/n 272-1092
http://www.radioshack.com/product/index.jsp?productId=[/INDENT]2103780
or
McMaster p/n 1505K414
[INDENT]
McMaster-Carr[/INDENT]
They are called 12V mini lamps
The Radio Shack bulbs are a little smaller than the stock ones, but they will still put out the same amount of light.
To remove the old bulb, unthread the wires, and remove. Thread the new bulb in, and cut the extra wire off.
The McMasters look to be the same but I never tried. I need them a little brighter.
McMaster also has bulb condems p/n 16925K11
McMaster-Carr
What would be cool is to find an LED replacement!! These are not as bright as OEM and I would love BRIGHTER!