So my wife got in an accident in our Tahoe about 2 years ago, totaled but we still drive it, after the accident the brake lights were stuck on. I did some internet research and change the switch above the pedal as that seemed to be the common culprit it didn't help.
I was pissed I was about to just rewire the rear lights since like I said it is totaled but still drives fine, well playing around with the switch one of the wires to the harness popped off. It must have been barely hanging on when I changes the switch. I had to pull it out and solder it back together, which was a pain under the dash. That fixed mine. So not that you want to pull the wires hard as the are tiny wires, you might just give a slight tug and make sure they are all good. There are 8 wires I think it was that go to that harness.