I agree with hangman. 2nd and maybe 3rd opinion. IMHO if a dealership (or any of us for that matter) can sweep something under the rug they (we) will. Good luck.I’d go to a different dealer and verify. It could be that mechanically they are the same but could be a new different Transmission Control Unit.
The dealer should be able to look up what software your transmission or ECU is currently using and tell you. They are gate keepers regarding this issue. You need to be a pain and complain to get this update. The service tech was pretty cool at my dealership. After a lot of debate I told him to hop in and let's go for a ride. During the test ride I would coast at low speeds, press the gas pedal and tell him when I was doing so, "pressing now" and then he could feel the lag and delayed response. He agreed it wasnt right...
I had the tsb/transaxle swap done on my 17SE made 2/17. They wouldn’t do the software update and the transaxle swap simultaneously. I had to drive it for 1k miles and then go back in and then they did the software update. The car was noticeably more responsive off the line after the software update.Technical Service Bulliten. It's when a manufacturer knows about an issue, but is not severe enough for a recall.
Some people got the software update. When I went in, the Dealer declared my transmission bad and replaced it under warranty. It's definitely better than before, but I still feel that Toyota's programming makes it sluggish. It's possible you can get used to it, really pressing the pedal more than you would normally do on a different vehicle.
The 6 speed transmission is more linear and responsive. Foot of the gas and then back on, the transmission re-engages quickly and accurately. Same scenario, with the new 8 speed transmission there is a hesitation as the transmission searches for the correct gear and then re-engages. It’s more noticeable in the low end and in around town driving situations because that is when u want that instant response. I decided to go 19 AWD LE. No regrets. I test drove a bunch of 17 on up low mile siennas. With COVID just hitting when I was about to buy it was easy. The dealerships around me would hand me the keys and send me off alone to torture their cars. Ha! I even had an 18 AWD from Carvana that arrived with some body damage so I wound up returning it. To some extent the 17’s on up all have some delay. The 18’s and newer feel more responsive off the line I think because they have the newest software. I like the extra horsepower, the better gas mileage, and I do like having the 18 on up added safety sense-p which includes Automatic High Beams, Pre-Collision System with Pedestrian Detection, Lane Departure Alert with Steering Assist, and Dynamic Radar Cruise Control on all trim levels. The 8 speed requires you to “drive the car” a bit more. I’m okay with the delay and letting the car get there so to speak. Oh yeah, no difference in the AWD versus FWD and the delay. I did chose AWD because I like the way it accelerates and feels hooked up compared to a FWD. Off the line there is less of a squat and then go type feeling my FWD SE had. My two cents...I am looking to buy a 2015+ Sienna AWD - either XLE or Limited. Budget constraints say that that really means 2015 - 2017. I was excited by the 8-speed and 30 more horsepower in the 2017. Can I trust that everyone here will tell me to get a 2015 or 2016 and forget the 2017? Do the shifting problems occur across all trim levels and in FWD and AWD models?