I have a '01 Chevy Blazer (S-10 version) that has a Brake light constantly on along with the ABS light. They both come on at the same time. They don't come on right away when I start the car up after sitting for a while. But it seems when the engine is warmed up that is when they both come on at the same time. When it is extremely cold (like January in MN cold) they don't come on at all.

As you can tell I have learned to ignore them because both regular braking and ABS braking have seemed to work just fine. But I am now thinking about getting rid of it and would like to figure out how to fix it. Will this be a costly repair?