2003 GMC Fuse Box??

Ok guys my sister has a 2003 gmc sierra and the 12 way body plug in the fuse panel inside drivers door on dash isnt getting power. Can someone explain where that section of fuse box gets power from? The rest works its just the 12 plug???

Ok does anyone know what each of the wires are?? Lol. Its a 2003 gmc sierra 4x4.