ABS system

That is telling you something is wrong with the ABS system and if the breaks are locking up in snow, then you know something is wrong. ABS is not working. Take it and have it scanned for codes. They should be able to pick up on a ABS code which would point you into a direction for repair.

ditto up above, check the wiring and connections at your speed sensors on the wheels, could have a rubbed wire or bad/dirty connection.

I drove for a year with my ABS light on. I just drove very careful and tried not to drive in the rain. I finally had enough money to get them replaced. I went to a Ford Dealership and paid $1200 for my ABS module to be replaced. I picked up the car and drove away and the ABS light came on again and tge "service advancetrac" light is still on. I took it back to the dealership. They said they just forgot to reset the light but I now need new rotators. I was going to take my car back to Carmax to get this done. So I pick up my Expedition from Ford and the light are off. I think, great it's fixed. However, my breaks sound and feel awful! I was scared that I was going to get into an accident. All of a sudden my ABS light comes on again and the service advancetrac light comes on again but the brakes feel better now. No more noise and shaking. Everything feels fine now but my lights are on again. So is the issue with my rotators or my ABS?