New Torque convertor now ECM Wont Communicate

None.. just comes up as “ communication Error”

I'm not sure if it affects your year, but a fuse for one of the auxiliary power ports also powers the OBD port in some of these SUVs. You may want to check an OBD pinout diagram to see if voltage is at the proper pin(s). And check the power port fuses.

@Doubeleive might have a comment...

Make sure all your grounds are clean and tight. check wiring harness that you didn’t pinch anything anywhere..

68jay said:

If there is already a communication “error” in my scanner, will the adapt scanner work?

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No, you'll need to fix the comm problem first but not having a capable scan tool handicaps you bigly. I strongly recommend you invest in one so you dont have to rely on other people (shops, etc) to do basic diag and reset functions. Autel, Snap on, Bosch, etc all make them. AC Delco's Technical Delivery System also offers subscriptions to diagnostic suites, paid on a per-vehicle basis.

68jay said:

None.. just comes up as “ communication Error”

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Did you check the fuses in the drivers side & passenger dash end cap? the obd port communication is normally shared with the drivers side cigarette power port, so on the left side check #4,8, 27, 36, 50, 52
on the right side check # 4, 50, 52
it should show in the owners manual which fuses they are if you want to double check.
there are also a couple pins on the obd port you can check with a ohm meter, if one or both of those shows a open circuit or the incorrect ohm's then you have short to ground or broken wire in the lan bus. (or as noted above a bad fuse)
i don't recall the exact pins but you can just look up gm obd lan bus pins/ohms and there should be many links to the info.

Just an update, after checking the connections for the 20th time found the issue with the transmission plug notating correctly, I now have communication but still no start.. no codes pop up..hopefully a TCM relearn will change that!?

I don't know if this helps.... A friend had a Chevy s10... The removal / replace of the torque converter required the transmission shop to do a 'GM required" learn procedure. Maybe a transmission shop may have some thoughts on this?

68jay said:

Just an update, after checking the connections for the 20th time found the issue with the transmission plug notating correctly, I now have communication but still no start.. no codes pop up..hopefully a TCM relearn will change that!?

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I don't know if there are seperate learns but the transmission relearn has to be performed while the engine is running and the transmisson temperature is at 160deg or more
so I would check the shifter position, that would be a reason for no start if it is reading anything other than park or nuetral it will not start.

68jay said:

Just an update, after checking the connections for the 20th time found the issue with the transmission plug notating correctly, I now have communication but still no start.. no codes pop up..hopefully a TCM relearn will change that!?

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Vehicle has to be running, transmission to operating temperature prior to beginning the fast adapt relearn procedure for the transmission.

Do you have a 'No crank - no start' or is it cranking over but simply not firing up?

NickTransmissions said:

Vehicle has to be running, transmission to operating temperature prior to beginning the fast adapt relearn procedure for the transmission.

Do you have a 'No crank - no start' or is it cranking over but simply not firing up?

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Just for my understanding, how do you get the transmission to operating temperature? Do you drive it to warm up the transmission, even though the fast relearn procedure has not yet been started?