She won't fire up. Please help me! I"m at a complete loss!

[jorgensensc]

Thanks for the replies guys! I posted the info about the tranny plug in hopes that it would help others. I honestly just came upon it by chance. I couldn't figure out how the plug was Turning in the socket and engaging. Just didn't make sense. But the tranny was driving the truck, so I thought it was connected. And I wouldn't have figured it out until I got the new computer. Then it may have still been blamed on the mismatch of engine and tranny.
I've triple checked the wiring and tranny fluid. They are correct. On the scan tool I get two codes. One saying communication error, and one asking for the mil light to come on. That tells me the ECM and tranny aren't communicating. I'm hoping when the 2011 ECM arrives it will then communicate with the tranny. Fingers crossed!

I do find it interesting that if the tranny isn't connected, I can drive around in 3rd gear. When the tranny is connected correctly, I can't get out of first. The ECM is supposed to tell the tranny when to shift out of first. So that is probably the reason it's staying in first. Also the 2008 6l80e tranny uses a brake switch wire to release the TCC. This gets wired to the ECM and also from the brake switch through the tranny plug into the TCM directly. On the 2011 tranny the wire still goes to the ECM, but that's it. There isn't a seperate wire that goes to the tranny. The ECM tells the Tcm when the brakes are applied and when to release the TCC. Small interesting changes.
On the 2008 tranny most of the internal switches are normally open, on the 2011 tranny most of the internal switches are two position normally closed switches. Small changes cause big headaches!! Thanks GM!
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