I don't know when this happened but my friend was driving behind me and called me on his cell to tell me to pull over. When I got out, I noticed that my (night) tail lights weren't on. When I pressed on my brakes they turn on, but when I let off the lights turn off. I checked the fuses and they're all fine. Is there a way I can check to see if its the bulbs or not because I don't want to spend money on new bulbs and thats not the problem.