If the ABS unit is disabled/disconnected and you have the vibration....
The rear rotors are warped.
The first time I had this problem on my 98 V70 I spent two weeks looking for the problem.
I replaced the front rotors, pads, bled the system, disabled the ABS, replaced the rear pads and finally replaced the rear rotors, zimmerman cross drilled. Problem solved.
Then a year later it started again, I put another set of rotors, brembo solid and no problem since.

A defective ABS unit will cause vibration but you only feel that on the brake pedal and eventually the vibration stops and the speedometer will stop working as well.