mossman77

My transmission (2011 SH-AWD) downshifts to 1st gear when slowing to a stop while in sport mode. This causes the vehicle to jerk. Why on earth would the transmission downshift to 1st gear while decelerating/braking? Seems like it should only do so upon accelerating again or at least not until the vehicle is completely stopped.

Reorge

It shall also automatically upshift from 1st to 2nd gear at a set high rpm.

losiglow

iTrader: (1)

The automatic up shift to 2nd gear is normal. However, I don't think it shouldn't downshift from 2nd to 1st. In fact, if you're coming to a stop, I believe it should shift straight from 3rd gear back down into "neutral" which is technically first gear but with the torque converter in stop/slip mode. That's what my 6AT does anyway.

mossman77

I completely agree. But my torque converter is locking up, so I get a nice jerk, which sucks.

Tonyware

It is entirely possible because of your driving style the transmission software has "learned" to do that. Try changing your driving style a bit, like drive more conservatively, and see if that jerking goes away.

hoonee46

My '09 5AT also shifts down to first when coming to a stop, but it does not jerk at all.
I figured it needs to because of the longer gears compared to 6AT.

Perhaps look into the torque converter / transmission software update - TSB dated 2016.
From my recent research, there is a clutch inside the TC (2 for '12+) that engages at higher speeds.
On the old software, this clutch may stay engaged even when you slow down, which causes shuddering and jerky trans behavior.

Basically, the torque converter is not slipping like it's supposed to, so the downshift to first is jerky.
This makes cruising at low speeds very uncomfortable, constant shuddering and jerkiness unless really really gentle on the throttle.
My car does not jerk into first, but I still plan on asking the dealership if the update was performed.

mossman77

I wonder if this is the same cause of the hesitation when accelerating quickly. It's like the TC is locking up after each upshift when it should be slipping in order to keep the RPMs up. This is one of the most frustrating things about my car. With the pedal floored, the upshifts should be quick and smooth. Not the case with my TL.

I bought it used in March of last year. Are you saying there has been another software update released since then? Mine is a 2011 SH-AWD non-tech.

dregsfan

The 5AT in the 3g TL, which I think is pretty much the same as the 4G 5AT, has 3rd and 4th gear pressure switches which affect shift quality, especially on down shifts. When my 3G had about 60k miles on it the downshifts (and yes, it will downshift to 1st gear) became pretty harsh, though in my car it was mainly the 4-3 and 3-2 downshifts that were harsh. From info I found here on Acurazine I had those pressure switches replaced, and the downshift harshness was eliminated. Maybe that's the cause of the problem with the 4G 5AT also.