Review on Enhance Your Vehicle's Safety with GM Genuine Parts D1586H Brake Light Switch by Adam Roman

I received a "Trailer Brake Service" error. The first thing that needed fixing was the electrical connections, but that wasn't the problem. The next step is to replace the trailer brake relay in the truck (AC Delco 20904439). This didn't solve the problem. It was found that this alarm was triggered 90% of the time when the brake pedal was pressed either at traffic lights or while driving. This was the next step and solved my problems. It's quite difficult to install, mainly because it was very narrow and difficult to access. Once you get it, it's pretty easy to replace. All you need is a socket wrench and needle nose pliers to remove the pin and swap out the device. Take a picture before you start taking it apart, but if you run into trouble there are plenty of YouTube videos that can help you.