I had an ABS sensor on a 95 pickup that came on the same time as the brake light came on. In that case I knew the two were related and I was able to have a Nissan mechanic disconnect the ABS system from the brake system so that only the ABS light stayed on.
What kind of vehicle do you have? Do you know if the ABS system controls the front brakes as well as the rear brakes? (On my 95 it was only on the rear brakes). They may be related, but they may not be.