02 Silverado Wayward back lights

[b1blazin]

Okay so I have a problem with my 02 Chevy Silverado 2500 HD. 

 

The problem is when I push on the brake with my turn signals on all my rear lights go crazy like a rave. Sometimes the reverse lights work at other times they have it. The tail lights do light up. The dash lights have both signal arrow indicators on when I push the brake but not always.

 

Initially my signal lights did not work. I replaced the combination flasher relay and I feel it made it better and I got the signals back. I also tried replacing the combination function switch w/ no results.

 

At some point my horn stopped working but now it does. I replaced the brake light switch affixed to the brake pedal & when I did everything was normal again!... But that's lasted not even a day after I went for a drive.

 

I suspect a ground but the grounds do not show Voltage drop. Wires look ok & fuses are solid. 

 

I hooked up my fifth wheel and the trailer lights do not work at all. Is worth noting when I was hooked up to my trailer I put my left blinker on and when I push the brake there was a buzzing noise and I'm not sure where it came from. Horn? But I have voltage from the 7 pin plug.

 

I do not have a wiring diagram but I have cleaned all grounds that I can find and I have inspected the tail light junction block and it seems to be okay I've ordered another one just to rule it out but I'm truly at a loss and I am pulling my hair out.

 

It worked fine after the brake switch but now square 1.

 

If anyone can tell me what I can do it would be greatly appreciated. Thank you. 

[Jsdirt]

There's a ground and/or wiring problem somewhere. The fun part is tracking it down.