ABS Brakes

Why does my 2003 Crown Vic, ABS Brake system pulse , when brakes applied in the summer time even on dry pavement, It is'nt the Roters or pads as they were just replaced, with new ones. It is in the ABS system.
Thanks
Arnold

Possibly a bad wheel speed sensor. If one wheel sensor is reading differently from the others, it will allow the ABS to activate. If sensors are OK, then it is either wiring or the ABS control module. Tests need to be conducted to see what is causing the problem.