Archived 94 trans shift issue

[PetesonM]

94'47rh 3500 dump minor mods fuel plate pushed, timing, exhaust, high flow air filter. Stock trans to my knowledge per original owner. About 250k mi. Not my truck.
Question being trans began acting abnormal not upshifting to 4th randomly about 1 mo ago and recently began acting like it is low on fluid. ( not moving when taking off from a stop for a couple of seconds then slamming into gear) the tc was doing the lock unlock thing as well randomly.
-The fluid was checked little low but not bad. Topped off
- Batt grounds cleaned, and new batt installed + chassis grounds cleaned + ground added from pcm screw to chassis.
-TV cable checked ok
- new TPS installed (cured all I thought, but now no 4th at all. TC will lock in 3rd though.
- new temp sensor was purchased but not installed yet.
Now truck is acting like it is low on fluid again. at speed will act like it has been put in neutral and then kick back in???
Looking for any other ideas. Suggestions welcome, Help please thanks

 

[cerberusiam]

At 250k with a dump box it is probbaly time for a rebuild. Put some gages on the test ports and see what is happening is your next step.

 

[PetesonM]

At 250k with a dump box it is probbaly time for a rebuild. Put some gages on the test ports and see what is happening is your next step.

I agree however the 96 in the group is getting a trans as we speak soooo that is lots of $ to do a second truck right away.
I was thinking accumulator? when i took it for a drive after fixing the grounds it drove great beside the tc lock unlock issue. it is weird to loose 4th right after doing the tp sensor. i was going to ground 4th to see if it is in the trans or wire issue good idea??
i will check pressures when i get time to look at it again this weekend. anybody with a link to pressure chart?
just wanted a list of ideas before i work on it again.
i cant for the life of me figure out how this trans is still alive??? lots of pm by previous owner i guess. RIP sir.

 

[cerberusiam]

Grounding the OD sense wire is a good start to trouble shooting whether it is electrical or mechanical. Might have lost the SBEC on it also as that is what controls OD.

Pressures can vary. Middle port on the passenger side should run from 50 psi to 120 psi if stock, it will vary based on throttle position running the TV cable. Gov pressure should be 1 psi per mph I think. Front servo pressure should follow the TV pressure in 2nd gear.

 

[Missouri Mule]

I take it you relaced both batteries?

 

[PetesonM]

Yes both batt replaced. Installed a new vss and temp since last post. Adjusted bands. Still looking for time to get the pressure guage hooked up. Next will be grounging the od and try to rule out electronic or mechanical issue. Thanks guys keep the info coming!

 

[PetesonM]

I will have to search again but I think I need to ground the center wire on the trans plug?

 

[cerberusiam]

Two of the 3 wires will not have power on them with the key on. One is OD, one is lockup. I will have to look when I get a chance to see how I have one wired.