general automatic transmission Q about lockout

On modern automatic transmissions, is the transmission designed to lock the torque converter in 4th (1.00:1) and any overdrive gears such as 5th and 6th?

Does it ever lock in 3rd or lower gears?

I’m sure the A750F in my 2nd gen locks in 4th and 5th.

I’m just wondering if that’s how most modern automatics are designed.

 

Your transmission locks up in 3rd through 5th in drive on acceleration and 4th and 5th on deceleration. See page 29 of the linked PDF. Generally, manufactures are looking for every opportunity to improve fuel economy they can get, so having the TC lock up beyond the 'traditional' range has become more common.

https://shop.ukrtrans.biz/wp-content/uploads/catalogs/A750E.pdf