Driving home last night the brake dash warning light came on. The brakes went from feeling great to squishy and close to the floor. I have taken the wheels off and have tried and traced the lines and see no leaks. I do not seem to be loosing any brake fluid. My ABS light has been on for awhile. I know it's the R ABS wheel sensor, I just have not gotten around to replacing it... This problem was literally all of a sudden. I literally got out of my truck to put gas in it and got back in and the problem is here.. Any ideas where to check?

 

I would start by tracing all of the brake lines, looking for leaks. Also check the master cylinder level.