"Door switches" may not be working right! Since switch is "grounded" side of the circuit, if not contacting right, (such as rust or dirt in contacts), the light isn't going to work. Open door, and find switch in front doorpost,-- somewhere probably below upper door hinge level!-- Wiggle switch around, - sometimes this will work contacts close enough that the switch will "work" again. If lights come on you at least know the problem. If the switch continues to give problems, then you will have to replace it, but if it just had some dirt or something in it,- it may "fall out" and switches will work normally!
Most "domelights" (the one in the "ceiling"), - are slightly different in operation, and most come on with "dimmer control" (for dash lights) turned all the way to one side or the other, some have separate switch in dash though, so you will have to check and see which one you have. --- This is a "generic" descriotion! If light comes on this way, first of all you know that the bulb is good, also you know that problem is most likely in door switches or circuit to same ! Some doors have courtesy lights in doors also - if you have these, it is also possible that the wires (between doorpost and door) have "flexed" so many times that the wires have broken from "metal fatigue"!- If you have gotten in and out a "million times" it is possible,- though usually it takes about 10 years of "normal" use to do this! Obviously, - if switches bad "everything would be dead", but if you had lights under dash, and in doors both, - a good switch would still turn ones under dash on, but ones in doors with broken wires would be dead!
If none of these clues gets you there (I of course assume you checked the bulbs first), if you want to "troubleshoot" problems yourself, - I suggest you go buy a "Haines auto repair manual" manual (sold at most auto parts/supply stores), specific to model series and year of manufacture of your car. You will find wiring diagrams of you year car in back of book,- and it shows all the basic wiring and connections so you can trace it down more easily. It wil lalso show you if there are other accessories running off the same fuse, in which case if the other accessories work ok, then you DO have power coming through fuse. TIP:= just because fuse "looks" good, - doesn't mean it is good! So subsdtitution of a known good fuse helps to verify if good or not! Try switching fuse with another circuit with same size one and see if those accesories still work or not! if switching fuses proves the one from courtesy light circuit is good, then just leave them where they are and proceed to next step.
PS The manual will save you a lot of money, and make repair much easier, -- if you try to do any of your own repairs at all!
