I'm guessing that the only cure for that is a new valve. Be prepared to spend $130 for it. I did all the researching I could and all I could come up with is that the damn thing rusts shut on you.
Does your brake pedal travel only about an inch before you can lock up your brakes? That was happening to me and that meant that fluid was only being sent to the front wheels. Once I replaced the RABS valve and got it bled, then I was able to push the pedal down about halfway before the front brakes started grabbing.
Now, half pedal will slow my truck nicely. 3/4 pedal will throw me into the dash, and I can't even get the pedal to go all the way down and still be moving.
It helps me alot that I have an 8.8" with the larger 10" drums.
