2011 GMC Sierra not shifting when accelerating

Truck isn’t shifting when accelerating from 35 to 60mph unless I let off the gas. When accelerating on the highway to merge it will go all the way up to 6000 rpm then will shift if I let off the gas pedal. Changed transmission fluid but problem is still persisting. Anyone have an idea what the problem could be?

How was that dome?


Brought it to mr. Lube they did a flush

Quick-lube places often use a generic fluid instead of the correct fluid and they often don’t follow the manufacturer’s instructions for replacing the fluid, so most of us here will suggest that you don’t do that again.


Some of them add a “magical” additive to that generic fluid in order to–supposedly–make the fluid work properly in all vehicles. :smirk:

I recommend that the OP have his trans fluid changed at an independent* trans shop, and that he have them diagnose any problems that remain after the proper fluid is used.

*NOT a chain-run place like Mr. Transmission, Lee Myles, Cottman, or–God forbid–AAMCO. Those places will tell him that he needs a complete trans overhaul, even if only a minor repair is needed.


Possibly a bad transmission control solenoid. A good independent transmission shop can tell you what’s wrong. As long as Mr. Lube used Dexron VI fluid (which should be specified on your receipt), I doubt they did any harm.