2001 S80 Brake grinding

[pdogi]

Hi- hope you can help! When I apply the brakes about 50 percent of the time I hear what seems to be grinding- pulsating- almost like the antilock is activated. Brakes were checked and pads are at 90 percent.
Rotors are clean with no rust ridges. Both front speed sensors have been replaced in the last year. It is not all wheel drive. There are no lights on on the dash! I want to sell this car and someone driving it will think the brakes are grinding. I have not had it scanned!