i tried to replace the left brake light, but it still has the same problem. it still lights up when the head lamps are on, but it doesn't illuminate when the brakes are depressed. is it a fuse problem? please help me!

 

most likely the bulb.

 

check the metal parts inside the plug make sure they are touching the bulb correctly

 

I'm sure you probably do, but make sure have the right bulb. You need an 1157 (the one with 2 filaments).

 

maybe one of the filaments are busted?? try another bulb or maybe u got an 1156 by mistake?