Sometimes the nav doesn't work. The climate and audio still work, but the nav shows a message "external system not connected". Then after a day or two it goes away. The problem always begins and goes away at engine startup. Anybody have any ideas? Is there a TSB on this?

I haven't done the nav hack but I did try installing a VAIS ipod controller. It didn't work so I had to take it out.

 

I am going through the exact same thing right now. Everything is fine w the system except no navigation. (been out 4 months) After a successful nav hack. Previously had a VAIS ipod adapter also. The video in motion stopped working and woulnt play videos so i took it out . Now i get external unit not connected also back up camera is a blue fuzzy. Fly audio with our setup isnt easy. Might have to just replace w oem unit. what u think??