In addition to my '67 RS I have 4 other GM vehicles and suspect I am not the only one. One is a 2016 Suburban and recently the Navigation System GPS totally failed. Screen powers up but car doesn't know where it is. Dealer replaced antenna but then said the problem was a bad VCIM (some circuit board thing that controls all the nav functions). My research so far has indicated this a known problem at GM and the dealer network. It is related to the design and installation of the "shark fin" antenna that lets water into the antenna leads and ruins the system. The car has only 21,000 miles on it and has been garage kept since new. Unfortunately the 36 mo. warranty period expired earlier this year so neither the dealer nor GM Customer Support will do anything to assist in the repair. My question: Has anyone heard of or experienced this problem and how did it end up working out? I continue to try and work with the dealer but GM has shut me down completely and I am not prepared to let them off the hook without a fight. The navigation system these days is more than just a convenience as On Star and first responders can't find you in the event of an incapacitating accident without functioning GPS so I am exploring using NTSB or similar regulator to get GM to stop ducking this problem. Thanks.

There is a forum called inside GM news. I would post your issue there. I posted there when the paint was peeling off of my three year and one month Sierra. The dealer pretty much told me to kick rocks. After I posted there I got emails and calls from GM asking me how they could help. That worked for me. I would recommend trying that.