Ok first of all i have a pontiac firebird and the problem is that my rear LH side tail-light is on but when i press break it wont turn on, and the one next to it, and the oppsite side is working fine!?! Also the middle break light right under the spoiler wont work eaither no light at all replaced the bulbs 2 times to. i dont kno y it dont work ive replaced da bulb twice and it works but when i apply break preasure no light, i have no idea whats going on please help thank you.

 

if you are getting regular brakes out of the tail lights it rules out the brake light switch down by the pedal. My opinion about the third brake light underneath the spoiler is the contact pad that is between the hatch and the rear of the car by the latch, that gets a coating on it and needs to be cleaned or sanded to make good contact after a while. As far as the marker light on the rear driver side, check the bulb, check the wires, and check the inside of the socket, could be corroded.