From Mediastone

we have a 2000 windstar that has chattering brakes…what is the cause of this? thanks

Most likely the brake rotors are warped. Have someone inspect the brakes and check for runout on the brake rotors.

Tester

I agree. But post back with the results. It is possible that you have a malfunctioning ABS wheelspeed sensor. If, of course, you have ABS.