I have a 07 model 4l80 in a 06 gto. The trans was brand new from gm. Were using the pcm harness to connect everything up. The issue were having is we only have 2nd gear and reverse. I hook hp tuners up and can command each gear and have felt the solenoids click and cycled everything to make sure they are doing as they should and everything does with key on engine off. When it is running no matter what gear i command it stays in 2nd gear. With hp hooked up and running i have put it in gear and locked the converter out and it stalls the engine immediately so i think im getting power. Any ideas of what it could be or what else i could check?

 

Double and triple check your wiring and 12V positive and negative.

Generally when a 4L80E transmission only operates in 2nd and reverse... there is no power going into the trans... or it is in "Limp-Mode" electronically.

 

if it didnt have 12v i wouldnt be able to command the solenoids with hp tuners and actually feel them click would i?

 

sounds to me like you need to double check and make sure your tune has a 4l80e segment swap complete

 

If you can command the solenoids...

Then you indeed at least have 12v positive and negative to the solenoids.

 

Any other ideas on what to check? The tcm is not throwing any codes either.

 

I am assuming that you are using a GM PCM with a segment swap for the 4L80E transmission swap...
It is not uncommon for some codes to be set to ignore via HP-Tuners...
Are you certain that there are NO DTCs???

I do not really feel that shouldn't be...
What else has been modified?

Is this a 4L80E from a 4 wheel drive truck that has no Output-Shaft Speed-Sensor?

 

from what im told i dont have to do a segment swap With the harness from pcm and thats coming from the company. I sent them the tcm to have it checked and they said all was fine there also. I just dont know of there is something internal that could be wrong holding it in 2nd gear

 

No segment swap needed from what all others say that has done this on the gtos. The trans is from a 2wd 07 tahoe. Im wondering if something internal could be wrong and or hung that could hold it in 2nd gear.

 

If the transmission goes into reverse and second gear...

Then it is not mechanically or hydraulically stuck in second gear.

When reverse and second work...

Mechanically and hydraulically, so would first gear and third gear (the only clutch packs that we do not know about at this point are Over-drive and Over-run, as well as the Intermediate band).

First gear uses the Forward clutch (and the Low-Reverse band in manual 1st)
Second gear uses the Forward clutch and the Intermediate clutch (and the intermediate band in manual 2nd... we do not know if this band works).
Third gear uses the Forward clutch, the Intermediate clutch, and the Direct clutch.
Reverse uses the Direct clutch, and the Low-Reverse band.

From this information... we know that 1st and 3rd gears operate because the shared use of clutches in 2nd and Reverse.
The 1st and 3rd gears are not electrically or electronically being operated.

 

I would definitely do some further research on the segment swap.