2001 Yukon 4WD rear limited slip axle . Having the same issue you boys did . Under light braking condition at low speeds feels like the ABS kicks in and can feel it pulsate in the steering wheel and on the brake pedal . No C.E.L no ABS light . I've removed and cleaned all 4 calipers and retracted the pistons with a large C clamp , blew out all brake dust , bled all 4 calipers starting with the R/R and working back towards the master cylinder . Non of that fixed the problem so I'm gonna try to remove both front ABS sensors , clean the bores , lube the o/rings and reinstall and see if that will fix it . You would think if there was an excessive air gap due to corrosion or whatever that it would trigger an ABS code ?