One problem related to transmission not engage has been reported for the 2015 GMC Sierra 1500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 GMC Sierra 1500 based on all problems reported for the 2015 Sierra 1500.
On two separate occasions my truck has acted like it is in neutral while driving. The drive system disengages and the engine just revs. Once this happened while driving down the road, the other when the truck was stuck in snow. When it was stuck it disabled the 4wd system completely, rendering the vehicle stranded.