My pickup has what GM refers to as "phantom shift". while traveling on I5 @ 70 miles per hr, my pickup thru no action on my part, shifted into 4 wheel drive. Previously this happened while turning left or right at slower speeds. GM issued a "bulletin" in Feb. 2011 giving dealers instrutions on how to deal with, and repairs to fix this problem. A local dealer, using that bulletin, in December 2016 proceeded to "fix this problem with my vehicle." Charging me $849.35. In July 2017 the same problem re-appeared. The local dealer (airport Chevrolet in medford, Oregon) is now refusing to honor their warranty for their "fix in December claiming that becaust the computer in my vehicle is not "throwing any codes". GM is demanding that I get a second opion at another dealer at my expense when the other dealer has already espressed an oral opion that they know they can't fix anything that doesn't "throw codes". according to info I have discovered on line, this problem has exhisted with this particular model pickup since 2004 and now, GM is refusing to cooperate with me. Please help updated 09/11/2017

- Rogue River,, OR, USA