Originally Posted by repo

You would hear that surely and it would still drive with a cracked flex plate. Seems more like rear diff (especially if he was doing a u-turn, and he would need to unbolt rear shaft to get power at front diff I think), transfer case, torque converter or something like that.

Originally Posted by Jetboy

My guess would be either a sensor issue or transmission solenoids aren't shifting correctly for some reason. Or it's low or out of fluid. Like that transmission cooler line used for a flush came off and dumped the fluid out or something.

Or - given the age, did you check the coolant for a pink milkshake? Could have lost the trans fluid into the radiator.

Rear diff issues would still be drivable or at least moveable in 4hi and it wouldn't lock up the tires in park. When you put in park the rear parking pawl engages the transmission output shaft. The fact that that locks up the drivetrain downstream from there tells me the issue is between there and the engine.

I don't know how you'd diagnose the transmission beyond that without pulling something apart or having a diagnostic software.

The torque converter is a fluid coupling that very rarely would wear out or break to the point where it wouldn't move the vehicle or give at least some forward motion. Unless a catastrophic internal seal blew out or something.

Taking a random guess that you should put no value on - My guess is some solenoid is not functioning or the transmission oil pump line pressure regulator is bad or something like that that's not engaging the clutches. The ECU is designed with failsafe systems that work around almost any individual solenoid failure to make sure it will still drive. So maybe that doesn't fit. Hard to know much more without better info from diagnostic checks.

Originally Posted by 02SE

I also saw more than a few customers who complained about similar symptoms, and the problem was the transfer case was in neutral.

Originally Posted by 02SE

Edit: However, if the OP can re-start the engine, then the flexplate is not broken.

Originally Posted by magnetic.gry.rnr

Was their Tcase manual or automatic?

Originally Posted by repo

Last question I promise but did you have that 1GR-FE "whine" some people have? Which is hard to locate the source and Toyota says is all fine and normal?

Sounds sort of like a turbo whine from tge engine while you're driving and changes with rpm but it's actually coming from the front of the transmission, from the pump probably.

Originally Posted by DanTh3Man

@magnetic.gry.rnr - I've got no idea what's going on but can you update this when the dealership figure it out?

Originally Posted by 02SE

The A750 is a pretty stout transmission, which has a history of being very durable and tolerant of hard use, and even abuse.

Did you own this 4Runner from new?

Originally Posted by magnetic.gry.rnr

No I didn’t buy it new but is in immaculate shape and everyone who has ever looked at it from a mechanical perspective has always commented to me about how good of shape it’s in.