NEED HELP WITH ESCALADE NAV SYSTEM

I HAVE A 2004 ESCALDE.  I HAVE INSTALLED A FACTORY 2006 ESCALADE NAV SYSTEM WITH TOUCH SCREEN.  I AM TRY TO DEACTIVATE THE "OPERATES ONLY IN PARK" FEATURE.  I UNDERSTRAND THERE IS A WIRE IN THE NAV HARNESS THAT CAN BE DISCONNECTED AND THIS WILL FREE THE SYSTEM UP SO IT WILL OPERATE WHILE THE VEHICLE IS IN MOTION.  I WAS ABLE TO DISCONNECT THE ODOMETER AT THE MAIN COMPUTER.  THIS ENABLED THE NAV SYSTEM TO OPERATE WHILE THE VEHICLE WHILE MOVING, BUT I LOST MY SPEEDO OPERATION.  ANY HELP IS APPRECIATED.  JIM CLEMENS - ROCKLEDGE, FL.

I believe "tv and nav 2 go" (do a search on google) has a solution.  

eric,  thanks for the advice.  i will give it a try.
 
jim

I just bought a 04 and would like to go to a touch screen nav.  I have seen several on ebay.  How difficult was it to swap out?  Is there anything that can be done only by a dealer.  Thanks.