Silverado Tow Vehicle: Service Trailer Brake System?

evanrem wrote:
What timing, I had the same problem and did some research on it and thought it might be the brake switch. I had some other issues with my Silverado so I took it to the shop this week and sure enought that is what it was.

Is the brake switch accessible from in the cab? I think on my truck there is no brake switch - the code C0131 says "master cylinder pressure sensor intermittent". On my previous TV there was a switch and the aftermarket controller used inertial sensor to adjust trailer brake output but my current TV knows how hard I'm pressing on the pedal.

For other responders, the error occurs without the trailer hooked up so it's not the 7-pin connector.