I have a 2010 g37x sedan, and I got LED tail lights, but the passenger side brake light is dimmer than the drivers side light. I plugged the passenger tail light into the drivers side harness and it was still dim, so I know it has to be something inside the tail light. Does anyone have an idea as to what is wrong with it, and Is there any way I can fix it without taking apart the tail light?

Also it is only the brake light. the turn signal is just as bright as the drivers side.

 

No one ever answered your question. You need to check voltage at the plug. It could also be a poor ground.