2 wheel hi

Found this on a silverado forum When the truck shifts but feels like it goes into neutral first, or shifts 1st to 2nd then straight into neutral (would make high RPMS) it is called fail-safe mode, or limp mode. It is a computer problem that would come from a number of things, ours came from the "back-up neutral safety switch" or "PRNDL" switch, it tells the dash in the truck, and the transmission what gear YOU want it to go into when you put it in PARK, REVERSE, NEUTRAL, DRIVE, 2ND, or LOW. If when you put it in gear and it does not highlight that gear on the dash, chances are, there's something wrong with the PRNDL switch in your truck