brake peddle vibration

[gravedig02]

2002 F-250 7.3L
Recently i had my brakes inspected, everything turned out good. When driving and go to apply my brakes everything is fine until i slow to about 10-15 mph and my brake peddle vibrates and pulsates slightly make the braking feel as if my abs isn't working , my brakes stiffen up, then proceed to work correctly from about 10mph until i stop. I have no abs light coming on, brake fluid is full. This happens almost every time i stop. at about the same speed every time. Please, if anyone has an idea let me know.

[FMTRVT]

You've got an ABS sensor that's starting to act up. It incorrectly reads at the lower end of it's resolution causing the ABS controller to think a wheel is skidding, so it activates. It drops out once speed is too low, where ABS would normally deactivate. The speedo may say 10 mph, but it's actually slower then that, fooling you due to the slow response (hysteresis) of the speedometer itself.

The usual culprit is the rear axle sensor. Sometimes it's just a matter of the sensor getting too much iron wear debris on it's surface so it somewhat masked in reading the tone wheel at the slow speed. But it seems the sensor can also go bad over time, IMO from the wear debris being on it's surface over time.

The first easiest solution is to remove the sensor out the the top of the rear differential and wipe the surface off to see if that solves the problem. The next step is to either read the system for codes (which sometimes will not show up since this is not a hard fault) or use equipment to graph the speed readout to see which of the three sensors is dropping out. If you have RABS, then you only have the rear sensor. Often it's cheaper to just replace the rear sensor then get things read.