Under warranty, thank goodness! It’s the AA80E/Aisin TL-80SN 8-speed that got put into the Lexus LS460 and is still used today in the RS-F/GS-F/IS-F. What are the odds?
Of course GM got their dirty meat hooks on it which probably ruined it. “Upgrades to the transmission, which AW had been producing prior to the 2014 GM applications, include additional heat-treatments on gear sets and other internal components, and additional clutch plates” (articles.sae.org/11942).
The tech report below tells the whole story. What’s a “TAC,” though?