help with my lighting issue?
 

So i have a 2012 mazda 3.
And recently my dashlights and my taillights do not go on when when i flip my headlights on
I checked all the bulbs and the fuses
For some reason the "taillight" fuse is getting a very weak power strength , i changed out the "daytime running light" relay and still nothing
The previous owner had some subs and amp and stuff installed pretty badly, i ripped all the wiring and stuff out cuz i tbought it may have been draining power
Any ideas? Thanks