Abs module light is on

Professional scan test of ABS will determine WHY light is on!

I have a ford escape limited 2005 6 cylinder the ABS break light been on for a while had it checked and said to be faulty light. Now when letting off the break & having to step back them, the break locked up. yet while stepping on to break your thrown very fast i might add in to drive with out even on the gas. I almost ran into the car in front of me at Windy's! Please help I have no idea why this happened! Or what the cause may be!!!!