2006 Mazda 6 Automatic

All the lights in the back are on when I switch the headlights on.

But when I hit the brakes, none of them brighten up for the brake.

HOWEVER the wing lights do light up when I hit the brake. It's probably the only thing that has kept me from getting pulled over and/or rear ended lol

A buddy of mine told me it was only the left one that was out about a week ago so today I decided to fix it, and found that both sides weren't brightening when I applied the brakes.

Does it just sound like faulty bulbs or is this something else?

Thanks in advance!

 

If lights that are not supposed to be on w/the brake lights are on, I would have to guess a grounding problem.
This usually indicates that the lights in question are trying to ground at the next easiest place, in your case through another set of bulbs that are not leaving enough power left to light the correct bulbs. In essence, its creating its own "floating ground."

The easiet way I know of to test this theory is to take a VOM or test light, find a good ground and see if the light sockets show positive power to them.