I just re-installed my Z2 in my 2012 Sierra. The Rear Camera is working, The hard drive works all the audio settings work. However almost ALL my Nav icons are grayed out and not usable. I can not enter a destination set my regional settings put in an address to go to none of it works now. Does anyone know what I could be doing wrong? I have almost all the bars for signal on my GPS antenna so I know that is working.

You need to either correctly connect the parking brake and set the brake OR do the 2 wire bypass (see sticky in hacks section). If you already had the 2 wire bypass then a wire is loose or not connected.

Thanks you are correct I had the 2 wire bypass done wrong. I corrected and magicly it works, Lol. Thanks for the info.