2nd Gen Non-Engine/Transmission ABS concern

[bnbrown]

On my 3500 dually 2WD w/ all-wheel ABS the rear wheel ABS seems to release completely on slick surfaces (dirt, mud, wet pavement), no idiot lights come on, also if the truck is empty (75% of the time) and you need to brake heavily (on dry pavement) the brakes pulse, but seem to pulse very slow (only maybe one cycle per second max) making the truck feel like it is trying to buck you off... again never have any of the idiot lights come on (except during normal startup self test). So far this has only shown itself at speeds under 35. I searched through all the old posts I could find, but nothing seemed to be quite the same...

any suggestions would be appreciated as having the brakes release on 8000# rolling along can be hard on your shorts...