Is it possible for a bubl to only work when braking? The bottom bulb in my tailights only works when I press on the brake, not when the lights are on. Help!

 

Sure, it's possible. This is because a brake/tail light bulb has 2 filaments in it. You can lose one (in your case the taillight) and the bulb will still work for the brakelight. Change the bulb and you should be good to go.

 

Could also be a fuse for the tail lights.

 

I will check that out, thanks guys...