Brake problem

Allow me to add a comment of value. I read about this same symptom on a Ford truck with the older RWAL system, (rear-wheel anti-lock brakes). The cause was metal chips collecting on the magnet for the rear sensor. I don't remember the theory, and I can't remember if the metal was filings from normal wear, or tabs breaking off the clutch plates for a locking differential. Seems to me it was the tabs, and removing them from the magnet on the end of the sensor solved the problem. That sensor was on top of the rear axle's center section. If you have an individual sensor at each rear wheel, this wouldn't apply.