P59 Controller Load Different OS & Segment Swap HELP Trans Not Working.

Hello, I have a 2005 Tahoe PCM with OS: 12606961. I am going to have it control a LQ4/4l80e combo in a 68 C10 Pickup. I do know (after much research) that I can't perform a segment swap for the 12606961 since there were not any 4l80's with that OS. I have a licensed 2004 Silverado 4.8 with 4l60e already not being used with OS:12587603. I grabbed a 2004 Silverado 6.0/80e file with the same OS and did a segment swap on it and copied all the 6.0 engine parameters over. I performed a write entire to the 2005 Tahoe PCM and everything went well. Engine runs etc. but the transmission does nothing. Yes, I removed the white and black/tan wires and moved the brown to the S pin on the connector and wired in the second speed sensor to pins 22&23. However, when scanning the trans always show that its in 2nd gear. I had an fault code of a bad 1-2 shift solenoid so I pulled the pan. Bench tested both shift solenoids and the are operational. Double checked the trans plug to the pins on the PCM and they all match.

Before I put the pan back on and filled the trans I just pulled the solenoids back in and turned the ignition to run and started logging. The fault code is gone now but it still shows 2nd gear when in park. I do have a PRNDL on the trans and it does reflect the column position. So I tried to manually command the trans shifts through the scanner and I see the gear change from 1-4 depending on which one I command, but I don't hear any of the solenoids click and when I am not commanding a gear it jumps back to 2nd every time. Nor do I hear the TCC apply when I manually trigger it as well. I am kinda stumped, I thought I might not be getting power to the trans and was going to check that next. But I do have trans temp and the speed sensor did work when I had it idling up on jack stands in gear.

After researching before I wrote this thread I found that it might be a problem with the tune file segments didnt take. So I remade a new file with the same base tune, performed the segment swap and re flashed the PCM with a write entire. But still have the same results.

Thanks in advance.

Or I had a thought. I have a 2004 Yukon Denali. Should I just take that PCM, do a seg swap to an 80 and run that? Then use the 2005 PCM with the 12606961 OS and since it already is setup for a 60e just run that on the Denali? The only thing I might have to change is the alternator & plug on both. The 2005 PCM uses the 2 pin plug PWM. Just trying to think of options if the 12606961 OS is that stubborn loading a new OS and seg swap to.

Anyone have anything to test or try to rule out a PCM or transmission issue? Does the stuck in 2nd gear mean its in limp mode by chance?

I don't think many of the guys get over to this part of the Forum lol

Hopefully you have figured this out by now - but if you haven't

just try writing (write entire) a 6.0/4l80e OS from a 2004 3/4 ton chevy/gmc to your existing PCM (your file may be corrupted?) - if this doesn't work still then you may have to replace the PCM

I will attach a file for you to use....