Help with 4L80e swap, transmission won't shift
 

Hey folks,

I need help from the masters. I had a TH400 in my car, then I put in a 4L80e. This is behind an LQ9. Did the wiring, had the PCM programmed, but when I fire it up, the transmission won't shift at all, stuck in P. The linkage hooked up correctly, got no problem cycling through the gears. I connected my bluetooth OBD-2 adapter and looked at engine parameters using the Torque app on my phone, but of all sensors I can read (nothing transmission related) everything looks OK and there are no codes at all.

I don't know if it'd help getting one of these tuning suites such as EFILive or HPTuners to get more in-depth info, or if there's some other troubleshooting I could do to get this going. The transmission I got was a rebuilt unit by a local shop, new stock TC, and it should be all good to go.

Any ideas?

TIA,

Dante

When you say it cycles through the gears just fine you're talking about the shifter? You move the shifter through the gears but it never comes out of park?

If that's the case it sounds like they didn't engage the manual valve when they put the valve body on. Pull the pan and look.

I think you're right. Drop pan and make sure that the shift mechanism is hooked to valve body. This happened to me when I shifted to 2nd at the track except it was stuck in 1s.
See the lik S clip lying in the pan?
This was on my TH 350 but you get the idea.
https://cimg9.ibsrv.net/gimg/ls1tech...917d82afc.jpeg
https://cimg0.ibsrv.net/gimg/ls1tech...7e6949308.jpeg

That's exactly the problem. The shifter moves through the gears but there's no gear engagement whatsoever. Looks like I'll have to drop the pan.

After thinking about it a little more it would likely be stuck in L1 instead of park if the manual valve were not engaged

https://cimg8.ibsrv.net/gimg/ls1tech...77f77305d8.jpg

Ordered a transmission pressure gauge set, will measure that before pulling the pan. I'll keep this thread updated with the progress on this issue.