I have a 2011 Sierra and I disconnected the TB to clean. I’ve done some research about reprogramming it. I did the 3 min on and 1 min off and 3 minutes back on and it idles fine just still shifts hard while downshifting. Do I need to get it reprogrammed by a shop? Or just keep putting some miles and should fix itself? The truck shifted fine before the cleaning
Ars you getting any codes? If you moved the throttle plate then you'll need a scanner to recalibrate it. GM has a relearn procedure and then drive it 25 miles but seldom that works. Recheck everything is properly connected and unhook the battery for 15 minutes and then reconnect. That will force a relearn but pcm may need recalibrated if that doesn't work.
I bought a new unit and that didn’t seem to work. No codes. PCM needs to be recalibrated I’m guessing ?