Tcase problems

[Steve6L]

My tcase doesn't want to engage on the go and when it does, it is this horrible grinding noise, so I instantly flip the 4x4 switch off. Wondering what's causing it not to engage and when it tries to what that grinding is, simple fix?

I know these trannies are supposed to be able to shift "on the fly" but is that the proper way to do it, I know when I used to have older chevs I would stop put them in 4x4 reverse for a few feet then be good to go.

Added not the t case will go into 4x4 no problem if I'm stopped.

Could faulty abs sensors cause problems? I know my speedo has been out 5km/h since I got my truck compared to my GPS never had this 4x4 problem though

[powerstrokelover]

Assuming our trucks are similiar in the owners manual it says EOF (Electronic On the Fly) shifting is at 3MPH. I have had some similiar issues but mine dont like to go into 4low when im just sitting in neutral. My motor dont even wind up.