Hi all, I have a 05 Sienna w/ 140k miles, and have owned it since it rolled off the lot. It has had an issue for as long as I can remember where it hiccups when trying to shift from 3rd to 4th. When it starts to shift at a higher speed (~40mph), it will briefly shift to 2nd, then back to third, then to 4th.
The Tranny fluid looks a little dirty, but I'm not sure if changing it would make the problem worse. Please advise. Thanks!
Since it's done it since day 1 and after 140k it's the same, I wouldn't mess with it. But likely it's spec clearance issue inside trans that isn't ideal but ok.
Have you done maintenance on the trans before (fluid and filter)? If so, yes but not necessarily for this issue because it's unlikely to change that but to increase longevity. Now if you haven't, it's a gamble changing it and I wouldn't make that decision without seeing and smelling the fluid myself.
I personally haven't done maintenance on it, nor do I know if it has in the past. I'm concerned that it's still the original tranny fluid. I started driving it 2-3 years ago, and noticed it almost immediately.
With it being my mom's vehicle, I don't know the service history.