Q: ABS modulator and brakes activate under 3 mph.

I have replaced all 4 speed sensors both rear hubs , right front axle, ABS controller, Modulator pump, Ignition switch , relays and checked all fuses ,front bearings are good cleaned the rust off the wheel speed sensor pads. I have been reading about the Yaw sensor and the main and secondary Transmission speed sensors and see that they are part of the system could they stop working under 3 mph ??. Trans shift evenly no jerking and speedometer works fine . The idle and speed increase are smooth. My scanner does not pick up anymore codes now ,they are all cleared with doing the work so far. But this problem does not go away . Any idea what else could cause this ,I cannot find this problem on the net anywhere .

My car has 160000 miles.
My car has an automatic transmission.