Transmission issue

MBW

I have a 2011 Yukon Denali, I have owned this suv since 2014. Was lease turn in. It has 186k on it but has always been taken care of and garage kept. About month ago I noticed that when I came to a complete stop it would shift in and out of gear twice. Just like clockwork at almost 100% of the time. Also it had a little bit of shudder at cruising speed.( between 40 to 60 mph). I took to local dealership and I was told they don’t know what it could be. The mechanic there said they don’t really work on them they just replace them with new ones. Oh yeah the price for replacement was 4400. It was not throwing any codes so he couldn’t really say. Such a waste of time. So in my research it seemed to be torque converter. So I had it replaced ($900). Shudder is gone now but still going in and out of gear at stops. So I ordered a new Tehcm ( Transmission control module) ($500). When latest repair was made the mechanic, (not dealership) said everything looked fine. But it still has the same problem just not as bad. I’m at a loss and need help. The local dealership is a joke here. Can someone help me diagnose this. If I had the money I would just replace but outside of the stopping issue trans works perfect.

thecardoc3

The 6L80 transmissions encounter wear in the front pump assembly. Transmission specialists have equipment or work with a machine shop to cut the wear out of the pump cover, replace bushings etc instead of replacing the pump. The torque convetor was part of the original failure, the TECM was probably not. The worst part right now is all of the wear materials that came out of the torque convertor and damaged the pump are in the transmission cooler inside the radiator, that's why it doesn't show up when looking in the pan.

As far as the dealer not having anyone that can fix this or know more about the failure beyond just replacing parts, there has been a lot of consumer pressure to force pricing down for decades. In trying to meet that expectation mechanics/technicians saw stagnant if not erroding wages and standard of living. This occured while the work got harder and the tools that they had to add to their boxes got more expensive so there just arent enough of them around anymore and that isn't going to be fixed anytme soon.

There was also a prevailing idea that it was cheaper to employ people who could replace the assemblies and not learn to rebuild them. Plus the shop got to make profit on the part and if something went wrong someone else was on the hook for the warranty.