Possible Transmission sieze, Gen 2

CoryDog · 2025-10-05T03:53:09-0400

Hi all, looking for any suggestions how diagnosis suggestions for a transmission failure, or the likelihood that it could be an easier fix that wouldn't require pulling/replacing the transmission.

Friend has a 2009 Sienna LE FWD (2gr-fe) with a ~250k miles that locked up the front wheels while he was driving the other day. One of his front wheels even sheared off the wheel at all 5 studs. After getting it towed, I poke at it and both wheel hubs seem to spin fine in neutral and park, but put it in drive and the hubs are locked up. Putting it back to park maybe some kind of buzzing/grinding sounds drive for longer than it should take to shift before it quieted down. But then the hubs could be spun again. It will go into reverse and backup and doesn't seem like there are issues there.

Any chance this could be a linkage or solenoid I could get to from the outside of the case? I have done some heavy home mechanic work on these but I know very little about where to start with transmissions. Does anyone have any driveway diagnostics we could do before he just gives up on it? Can't find any posts with the same situation.

stulew · 2025-10-05T10:34:08-0400

Inspect whether the 5 wheel studs actually sheared off, or if they failed in fatigue, meaning they weren't torqued properly. Fatigue markings means friend drove a long time with studs not being tightened....and that it wasn't the transmission's fault. The markings will look like this: https://www.researchgate.net/figure...acrograph-and-schematic-of-fracture-surface-of-one-of-the-bolts_fig11_282500927

CoryDog · 2025-10-05T13:36:47-0400

Thank you, but not really worried about fatigue of the studs here, the big issue is that the transmission is locking up when we try and put it into drive, and that's what happened when the wheel broke off.

BillG · 2025-10-06T08:51:55-0400

Maybe I'm misunderstanding, but the transmission is supposed to be "locked up" when in drive. You're engaging the wheels to the engine, through the transmission and drive shafts.

I can't comprehend the forces required to shear off 5 lugs. I would have thought the half-shaft would have exploded at the outer CV joint. Are you sure the transmission is the right place to start your diags? It seems like the problem is more likely in the hub/knuckle/wheel assembly. I've seen plenty of stories about a bad speed sensor or tone ring that engaged ABS in an emergency braking. Throw in a sticky slide pin and weak lugs from being over-torqued and stretched with an impact and you might get to the point of shearing off lugs.

I think this requires a comprehensive diag, starting at the hub and working inward, before condemning the transmission. At the very least, I'd do a drain and fill and see if metal chunks come out of the fluid.

circus · 2025-10-07T10:51:00-0400

BillG said:
weak lugs from being over-torqued and stretched with an impact ... to the point of shearing off lugs.

Common for the inexperienced person getting his hands on an impact for the first time. Don't ask. Not me.
Otherwise the tires would just skid.

CoryDog · 2025-10-06T11:21:18-0400

That's fair, you make good points, it does seem. I wonder now if it was a 1/rev ABS issue or something that broke the studs and messed up the transmission.

He had done with brakes recently, so the lug nuts could have been loose and a bunch of ABS shocks could have caused them to fail (he did tell me yesterday that there was a 1/rev impact sound coming from the wheel that failed before it failed, which is on the opposite side of the car from the transmission). But something definitely went wrong with the transmission since both hubs can now be rotated in neutral, park, and reverse, but are frozen in drive. So that makes me think that the forward gear in the transmission has to have gotten messed up and ultimately that will be the car killer even if we never figure out what happened to the ABS.

Possible Transmission sieze, Gen 2

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