01 Ram with Sure grip,
similar problem, my sensor was eaten alive.. I replaced it and at 60 MPH the ABS light would go on until I turned the ignition off and reset the system..
Bottom line problem was a very serious breakage in the sure grip that allowed large parts to hit and destroy the sensor and two teeth off the tone ring..
Tone ring is only serviced with the sure grip from Mopar.. or salvage yard parts..
I was able to repair mine (tone ring)using a MIG welder to weld new bumps on the ring and file them to match the others..
had to install a new sure grip as well..