I had that problem after I bought a used 2006 Explorer. It was not the ABS. It was the front end. For some reason, when the front end left bushing got damaged, it sent the wrong information to the ABS, making it stop working. In my Chevy Trailblazer, the ABS does not work at all, but the breaks work fine. I just don't get any "help" from the ABS. I would check the front right and left, and the sensors before replacing the ABS module. If you change it, even if you buy a used one, you will have to go to the dealer to reprogram it. They will lock you in a room and ask for your life savings to let you out.
