Anti-Lock brake knocking

Hi, I have a 91 Regal and have a sporadic knocking (every 2-7 secs)when braking (moving or parked) plus there is a voltage drop. I'm told it is due to a fauly anti-lock brake module and it would cost $4,000 to replace (not really practical for a $2,000 car). Does anyone know if there is any way to disable the anti-lock brakes or of another way to get rid of the knock ?