I think my rear side marker bulbs are burnt out, and have been since i got the car....i would check, but there's one problem: i dont know when they are supposed to come on, but they dont come on when i brake, or with turn signal, or even with tail lights. the front always come on with the headlights. what the problem is?

 

sidemarker lights come on when your lights are on (main/parking). if your rears don't light up, check/replace the bulb.

 

If your fronts are turning on and the rears are not... its a good sign they are burnt out.