just some notes i have picked up over the last few days of fighting with my new to me 1989 firebird...i have been fightint the int. lighs in this car and lookin all over this site for help and this is a short rundown of what i found on many different threads
1.check your fuses
2.the lighter shorts out (common)
3.the dimmer switch and headlight switch do go bad but dont spend money on them untill you have checked other stuff first
4.(firebird)there is a transistor under the dash behind the small fuse box to your right (it also has your flasher and horn relay in it) the horn relay became important in my case lol
5.dont know if its true or not but someone on this site said they got a transistor from radio shack for like $1 from my understanding there like 30 at the dealer
6.check to make sure the pos oh sorry po didnt leave any fuses out of the fuse block its hard to see up in there in the dark best done in the day timeor with a good light
7.also check your door switches
8.if everything you read on this site fails and your ctsy fuse still pops when you put it in take your horn relay out of the small fuse box and try another fuse thats what fixed mine along with finding that there is 2 fuses for the gauges one to make them work and the one i didnt know was supposed to be there cuz it wasnt there when i bought it that lights them up. the one that makes them work on my car said (gauge) in the fuse box and the one to light them i cant remember but it was right below and to the left alittle of the gauge fuse

anyway hope this helps im trying to get it all on one thread so all the stuff i know i missed please feal free to add

 

Fighting with an '89 Firebird...how familiar. Ahh, but it's fun. Don't forget to check the headliner dome light mounting tree/bracket whatever it's called that's under the housing. I had a very brittle and broken one which allowed one of the bulb terminals to just touch metal awhile back. That will pop the fuse instantly.

 

And the same goes for the hatch light in the rear panel... I had a cut wire on mine and blew that fuse until I fixed it.