1994 ford ranger abs light

I had a steady light on my 1994. On the front brake caliper assembly is a round metallic unit (about the size of a dime). Covered with brake dust and metal shavings, I cleaned them up and the problem was solved. Maybe someone can tell us what it really is but I am thinking it may be a speed/stop sensor.

All you have to do is remove the front tires to access them.

Let me know if it works!