2008 Sierra Denali Navigation Electrical Gremlins

[sgfootball2006]

Please help me with my navigation on my 2008 Sierra Denali. For about a year or so the navigation unit has been useless. 99% of the time it does not register the speed right as I am going down the highway at 60 and it shows me going through my neighborhood around 2 mph or so. I think the GPS is not updating the position right away since it does not think I am moving. When I go into the hidden service menu it shows my speed at only 2-3 MPH when I am on the highway. Now here is the kicker. When temperatures drop below freezing or near it like it is today in Houston... it seems to work perfect. I thought it was a fluke the last time it was cold but today it works again. Anyone have any ideas where to start? If I hook a mulltimeter up to ground and the VSS wire what should I be seeing? Any other ideas what it might be? This is the factory navigation without DVD playback.

[gmtech4]

sounds like a programming issue or a fault within the system ,,,,did ya ever take to a dealer?

[sgfootball2006]

Took it to a dealer but their mechanic could not figure it out. He never went into the wiring or anything though. Just tried to fiddle with settings. The main electrical tech was in the hospital.

[gmtech4]

gonna have to wait it seems lol