Transmission Lock Up

[Integrity Service]

Hello, We have currently got a 1985 Corvette with a 700R4 Transmission. The vehicle was bought to us with basicly blown transmission. Trans was fully rebuilt. Customer received vehicle back & has asked for more repairs on transmission as there is a lock up applying after 3rd gear engaged. lock up also applies after 4th gear engaged as per normal.
Question im asking is : Is it possible to remove the lock up between 3&4 gears? Is this lock up standard for this model? Have you struck this problem before???
Any help will be muchly appreciated.
Thanks.

[Not_ Me]

I had an 87. It didn't lock up in third that I can remember. But I never drove the car in third enough to notice. This could be caused by the ECM program. You may want to check that the ECM is working as needed before you tear the trans back out. With all of the different electronic parts in the early 700 it also could be just a wire in the wrong place in the valve body or a sending unit not installed in the correct place. I'd say this is in the electronics not the transmission itself. But what do I know? Not much, I still drive a chevy.(when it runs) Good luck.

[TEXAS-HOTROD]

There are 2 pressure switches on the valve body. One is for 3rd and the other is for 4th. You'll have to look in a trans book to find which one operates during 3rd gear application. You should be able to unplug the 3rd pressure switch and solve the problem.

I think 3rd switch has dual terminals and the 4th switch has only a single wire (but I could be wrong).
Hope you figure it out.