1990 B2200 A/T will not upshift

I replaced the transmission with another used one and drove it for 6+ months, no problems.

One day I jump in and head down the road, it stayed in 1st gear.
I can put it in P, R, D, 1, 2.
I can shift it from 1st to 2nd while driving.

Can anyone tell me if there is a speed sensor, electrical sensor or is it vacuum controlled?

I found these vacuum diagrams,
Could it be the servo diaphram? I'm not sure what that controls.


Transmission fluid and oil levels are perfect.

It does run out of water over time... it leaks on the passenger side of the transmission. (relevant?)

Any help would be appreciated.

Sounds like to me, no offense meant, but you may have been sold a lemon tranny? Usually when this happens it's clutches inside not being shifted around or a sensor malfunction, or vacum lines like you said, i would try checking all my lines make sure none may have slipped off, and as for the water dripping out of it.... idk that don't even sound good on its own just saying. but i wish you luck with fixing it and hope you didn't get a lemon tranny.
As for the sensor, well i only know one way ( myself personally ) to see if they are bad... old fashioned just replace it till none to be replaced no more lol

Ifix... there are two setups for A/T on these trucks, one is electrically actuated and the other vacuum. I'd look at those actuators first before thinking it's trashed.

If vacuum actuated check the line that goes up to the intake manifold.

If Trans Fluid is leaking from the actuator(s), it is probably toast - mine was.

Dan

I have the LE-5, do you know where the vacuum line would connect into the manifold? Or the electrical actuator would be?
The number of vacuum lines under the hood is ridiculous.

I'm going to crawl under it tomorrow and look for a vacuum line on the tranny.
And it's definitely water dripping... maybe a freeze out plug in the back?

Thank you both for responding.

i'd say if you search the tech write up section someones posted about these actuators/vacum lines their.

also, when was the transmission filter last changed? it could be just a clogged filter, not allowing anything to circulate and not allow it to shift properly

The vacuum line goes forward along the driver side of the tranny up the firewall and across the back of the engine about head level. It's a hard line below the truck and changes to a hose at the head.

You'll need to dry the block to see where the water is coming from. Dan

That was it!
Somehow, the vacuum line off the head came disconnected from the hard line... plugged it in and it shifts.
Much appreciated!

...now to find this water leak