Autotrac with manual transmission - anyone ever made this work?

[JJorgensen52]

HiHave run into a problem with my latest project - 1999 K2500 suburban 7.4L NV4500 swap, retaining the original NP246 transfer case. Got everything put together and working (GM was kind to me so it went pretty easily!), but I can't get the transfer case controller to work properly.

I have both 2hi, 4hi, and Autotrac *appears* to work, but I can't get neutral or 4lo. I just rebuilt the transfer case and it operates smoothly and easily by hand with the encoder removed. The encoder motor is in working order. When I plug up my scan tool and try to command a range change, it keeps telling me "transmission not in neutral and vehicle speed present".

My VSS is indicating 0RPM on both front and rear driveshafts and I have tried both with and without parking brake, always with clutch depressed.

The GMT400 never came with Autotrac behind a manual, but the S-10 blazer did using the same encoder. The control modules are different calibrations (have tried swapping them and that didn't help).

I am thinking, at this point, that the problem lies in my transmission calibration file, but I'm not terribly familiar with tuning beyond the use of a Tech2.

Any ideas on this one? Different thoughts or ideas appreciated!