So I’ve changed the multifunction switch the brake light socket and redone the ground wires and when my lights are on i still have the same problem. When i hit the brake it kills the drivers side brake and tail light altogether. There’s a blue Wire running down the frame and i don’t know where it goes. The factory wiring harness for the radio has been cut too, when an aftermarket radio was installed. Would that have anything to do with it?

 

Cutting a radio wire should not have anything to do with the brake lights. Now if there was some splicing of wires along with the cutting of wires, then who knows what could happen. You should be able to follow the blue wire till it ends at the back of the truck.