1998 Chevy Lumina antilock pulsing/ Brake performance not e

Hello, I have a problem with my antilock brakes. When coming to a stop, you can hear the anti lock motors or motor pulse several times. Sometimes three or eight times. I can tell especially in the dark because the headlights will dim slightly as you hear the pulsing. This happens below 30 mph and there are no warning indications on when this is happening. I have checked all the connections at all four wheel sensors by removing & reinstalling the connectors. I have also done this where the connectors come out of the floor pan & run to the rear wheel sensors. I also located the ABS control module under the dash and pushed connectors but did not remove them. Was wondering if my only last choice was to get it scanned or not. I did not know since there are no fault lights associated. Thank You.