It only shifts when i put my scanner in control mode and use the shifting program to manually tell the solenoids to shift. Essentially I'm bypassing the PCMs logic shift points by hitting an upshift or downshift button. My understanding of this transmission since its electronic is that it will only shift when the 2 solenoids are supplied 12V in a combination. The combination of the 2 solenoids turned on and off is what tells the tranny what gear to shift to. So as long as my scanner can send the correct signal to each solenoid, and it shifts accordingly, my guess is that the internal transmission function of the transmission is working, it appears to be something upstream of the PCM that's not telling it to shift. I have spent so much time on this i just have no ides what else it could be lol. I'm definitely no expert either, but i thought i knew a lot more than this. It's really got me stumped.this is a case where pulling the tranny fuse just might get you home. wish I knew that when I blew my second tranny. I think I could have gotten home.
I agree that the harness is fine. so if you can command the truck to shift, does it actually shift? I'm not an expert by any means just learn from experience you know... to me it sounds like you have a mechanical problem inside.