ABS PROBLEM???
 

my 98 gmc sierra make a grinding noise everytime while i am braking at slower speeds.
the mechanic told me my brakes were fine and that it is the wheel bearing that is the problem.
but recently my anti lock brake light has come on, and when the light is on the problem goes away but as soon as the light goes off the problem starts up again.
which leads me to believe that it is not the wheel bearing that is the problem.

does anyone have any ideas or similar problems?