Hi. If all the others  work I would think the GM file is corrupt. make a backup sd card just cause nothing much larger than the size you have now and then install it and see. Its always best to have a back up sd card incase you get problems with one. If that doesnt work and you have tried more than one Gm then you would have to buy the update pakage from Autel.Hope this helps. Regards Austin

Yes a new update will correct that, there was a gm update back in november of 2013
that disable communication with gm vehicles, that could have been the latest your tool
tooked but it has been fixed, there are no current issues of that kind with gm vehicles. I
will say yes is save to update.

Its safe to update.

 My 708 won't auto detect my GM vehicles and doesn't catch faults that my cheaper scanner does, this thing is a piece of junk, you get what you pay for, I am going to sell mine and get a proven Snap On Scanner with training videos and how to's and customer support that is readily available.

I'm in the same situation. My newly $800.00 maxisys update will not work on a 2012 colorado we have in our shop, but our ten year old system will. Does anyone know a fix for this. Just purchased new update and updated the VCI as well. Thanks