4l80 rebuild problems
I finally got the trans into the truck, but it’s only going forward. Anything outside of park is forward. The tune used is questionable, the indicator on the cluster shows 1 no matter what position the shifter is in. I’ve read that’s a common problem on some 4l80e swaps.
This sounds more mechanical than electrical. Like there are clutches that are stuck?
I did pull the PRND switch connector, and it wouldn’t crank. Still showed 1. Pulled the harness connector, would start but still stuck in 1st.
I will dig through some diagrams and probably pull the pan to check.
thanks for the reply!

See it there right under the plate at the end of the shaft and yes it is literally a nail lol . That is what keeps the rid from moving away from the manual valve
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Next problem, I have no reverse. D-3-2-1 all want to go forward. I haven’t checked the shifter cable adjustment, but even sliding the shifter back from P I don’t feel it kick into R. From a little bit of searching it sounds like the servo pin may be short, and not engaging the band. I sure hope thats it.
that’s the order everything is in it. I believe Im missing a washer, but the pin seems to travel more in the piston than what I’ve seen in other videos.
I plan to use this to check the travel
I would first put a gauge on it and see if i have pressure. I did I would pull valve body completely down, Inspect it and case for damage, Use thick gel to put all ***** back here they go and replace and try again. the ***** are about .250 so if you went lower than that they could certainly have moved from proper place probably would not even have to drop that low ,
But I have never tried to run an 80e with all the ***** out of place or missing .
I mean would seem off chance wise but for instance if a ball ended up in the fwd clutch feed and the direct clutch feed it could eliminate fwd and rev movement .











