they quit working about a year ago.there was massive pulsating when the brakes were applied.after not driving it for about four weeks i went out to get it started and take it out on the ice the brake light was on so i checked the fluid res. it was just down to the min mark.checked for leaks, none obvious.topped off the fluid and drove away.brakes have worked sweet since and still full of fluid. any ideas whats going on.84 fj60