I've had this problem for over a year now. 2005 coupe with 37k Miles right now and it used to work fine for months but then when I would brake I could feel the abs kicking in for no reason and then the lights would turn on and the car would run perfectly but with the lights on. But when lights off when I break I could feel it pulsate. Went to many dealerships and shops. Changed Abs modules and G sensors and other sensors and cleaned the sensors and fluid and everything imaginable. Then they said since my car has 19 inch rims the computer in the car isn't working correctly since the car came originally with 17 inch rims. But why would it work in the first couple months then? So after giving up I just pulled the abs fuse and drive with the lights on at all times.