Service Brake System error?

When the light comes on with that message it means the brake system shows an error. Because the ABS, traction control and AWD all use the same parts of the brake system any fault in it will also turn those off. The first thing to do is scan the truck for codes, when the light is on it stores codes related to the systems. With those codes you have a starting point to find the problem, that is because it could be a bad wheel speed sensor, a bad ABS module, even low brake fluid can cause an error, but looking at the codes will give you a clue where to look. If you don't have a scan tool that can read ABS codes many parts stores will scan the vehicle, but they may not scan the ABS system, depends on store policy. Get the code(s) and post them and we can track down the problem together.

I agree with Steve W. it sounds like a wheel speed sensor or the bearing hub is going out, when the brake waring light is on I would scan the system to see which code is present, this will tell you which wheel is having an issue.

https://www.youtube.com/watch?v=HvooM1X2SDs

Please go over this guide and get back to us.

That code is commonly caused by corrosion in the electrical connector on the EBCM, or if the ground to the EBCM motor is faulty. I would pull the connections off, look them over for corrosion, clean and reassemble. I have seen it be an issue in the harness and people run a different ground to the EBCM as a repair, however the location of the unit under the truck can make that a bad repair as it starts corroding quick.