TH400 Transmission skips 2nd gear

[jacksmad1]

Had my M1009 about 3 weeks now and have done a lot of work on it. My problem now is the transmission shifting. With the transmission in Drive, it will shift from 1 to 3rd around 20-25 mph. It skips 2nd gear. If I shift it manually 2nd gear works fine. Also if I am in 3rd and pull it down into 2nd, it also works fine. It just will not shift into 2nd gear automatically. Any ideas ?

 

[Westech]

its not skipping.. its going in to and right in to 3rd. What is happening is the trans moduator is broken or getting full vaccum signal from the pump. Here is what you do, first replace the modulato on the passenger side of the trans. It cost about 12 bucks from autozone or whoever. If that does not fix it replace all the vaccum lines wel you should do that with the modulator install really. But check to see if you are getting full vack out of the TPS. If the TPS is shot there about 125 bucks. There NOT cheap. I think Doghead has a couple he is selling cheaper (new units). But that is your problem, bad modualtor or bad TPS. Start cheap and go from there. 99% of the cucv modulators are junk from the get go. For 12 bucks and 5 min just replace it.

 

[jacksmad1]

You were right on. Went to Advance and got a vacuum modulator, brought it home, installed it, and it is now shifting normally. In fact it is so smooth, I really have to pay attention to tell when it is shifting. It is definitely going through all 3 gears now and it even downshifts when I stomp on it. Thanks for the advice, everything else I was reading was talking about clutches (yecch).