700r4 locking up to soon

[grpkewlaid]

Hello, I have a 1984 gmc K1500 with a 350 and 700r4. I bought and installed a rebuilt transmission. when the trans shifts into second it instantly locks the converter and chugs the motor down if I press the brakes slightly it unlocks and as soon as I release the brakes it locks up again also if I give it more throttle it will unlock.It does this in 2nd,3rd,4th.
When I unplug the elect connector it shifts fine.I realize it is supposed to do something simaliar to this normally but This one is locking right at shift while still under part throttle accleration and almost killing the engine. Any help would be greatly appreciated.
                                 Thank you,
                                 Kevin

[Crosley.In.AZ]

most likely the rebuilt tranny does not have the correct wire harness & pressure switches in it.

Perhaps there is a short in the wires .


The pan needs to come off to determine the problem

Hello, I have a 1984 gmc K1500 with a 350 and 700r4. I bought and installed a rebuilt transmission. when the trans shifts into second it instantly locks the converter and chugs the motor down if I press the brakes slightly it unlocks and as soon as I release the brakes it locks up again also if I give it more throttle it will unlock.It does this in 2nd,3rd,4th.
When I unplug the elect connector it shifts fine.I realize it is supposed to do something simaliar to this normally but This one is locking right at shift while still under part throttle accleration and almost killing the engine. Any help would be greatly appreciated.
                                 Thank you,
                                 Kevin