TH400 Transmission

[Berg]

could be a few different things. I'm not that great with automatic transmissions but it could have something to do with the governor on the side of the transmission in the rear. It is located under a little sheet metal cover with a wire band holding it to the case. It could also be a problem with the valve body or worse yet, could have a broken shell inside the trans itself. Even a cut seal wouldn't let it build pressure. They basically work on hydraulic pressure so any thing like that could keep it from working. Of course you could have a trans with a full manual valve body if someone raced it out once before. I got one of those and it won't shift on its own at all. It has to be put into each gear. It is possible to actually take off in 2nd gear with it. You can't run a kickdown with it for obvious reasons. Do you know the history on the transmission? Check the fluid level again also because after you install it and all the fluid goes into all the passages you can top it off and try from there.