Posted 4/15/2018 12:21 (#6710839 - in reply to #6710712) Subject: RE: Geosteer on JD 8410
Southern Minnesota Between Freeborn & Wells
Don't know if this will help but I have an 8310 that had a Trimble Nav II installed on it to work with an external steering valve that came with the Trimble kit (likely different than yours). The hydraulic plumbing required a load sense line to keep the hydraulic system from destroking. As I recall there were four choices for the orifice in this load sense line which I think depended on the age of the tractor. I believe there were some pictures to aid in choosing the correct orifice.
Apparently we used the correct orifice since it seemed to work fine for several years with an Ag Leader steering unlocked Insight. Last year, I traded in the Insight, Nav II and GPS towards an InCommnnd 1200, Steer Command and GPS 6500. The steering valve and plumbing remained the same. It continues to work fine.
Not knowing much about the combination of the load sense from the steering valve and the SCV, I think you may be on to something when questioning the orifice. Did you get a selection of different orifices with the kit? Are you certain that you re connected to the Load Sense Port?
When my first steering like this was done with my 8120 with ILS, the installer used the wrong port. We had problems when an SCV was engaged but it seemed to work fine otherwise. With an SCV engaged, the wheels would turn on their own even while sitting still with the steering disengaged. The letters LS were stamped by a port but it actually referred to a different port. Changing the Load Sense to the correct port cleared up that problem. The stack is different between the 8310 and the 8120.