i have a 2005 focus lx and have been having problems with the brakes.when pressed on normal driving the brakes would judder(abs kicking in) and the abs light would come on.took it to a mechanic who showed me my pads were very low,almost to metal, and that was the problem.he changed the pads for me but now,first time i press the brakes on driving, abs kicks in and light comes on.light stays on but brakes work normal. light goes off when engine off but then when started and brakes pressed first time, abs kicks in and light goes on again but brakes work normal. sorry for the essay but can anyone give me an idea on what it could be. thanks for listening.