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Hi all, we are having trouble with an avionic upgrade in our M20J replacing an old Trimble2000 GPS with a newer GNS530W. A KI525 HSI is installed with an KFC150 Autopilot. After flying back from the shop, we found that "automatic roll steering" was gone !?? Meaning the autopilot (KFC150) flying a multileg programmed flight plan (or any procedure like SID etc.) without any manual intervention for lateral steering. This used to work and does no longer! The A/P tracks the magenta GPS line in AP "NAV" mode, but does so only after a manual intercept course has been setup. After a waypoint turn >25 degree tracking is lost. The shop has "removed" a box labeled "GPS Box", which was connected to the NAV/GPS Switch. (which also has been removed). This apperently was an interface REQUIRED for automatic roll steering, converting the Arinc429 digital GPS signal to an analog input that the KFC150 wants. That we know by now, the box does something similar to the GDC31 adapter. http://www.peter2000.co.uk/aviation/tb20-experience/gdc31.pdf The avionics shop obviously lacks experience and knowledge to connect things correctly but also we and they lack WIRING documentation for this "GPS Box". (no other labeling or manufacturer visible). What I would like to know from fellow Mooniacs WITH KFC/KAP150 and GARMIN430/530 and working automatic roll steering is: What additional adapter equipment (other than GDC31) do YOU use / have installed to make it work? (make and model) Would be able to provide a link or a PM for wiring documentation for YOUR working adaptor? We hope to find somebody using the same adapter box we have (and trace the documentation this way). Thanks for your help Joe