LLY/AL5 No Data Received Error

[TorqueMonster007]

2004.5 LLY. Truck came to me with a LLY swapped motor as original motor was locked up. In V8 OBD2 it will recognize the ECM and all associated information. Can flash ECM via V7.5 and all is good, however when trying to read or full flash AL5 TCM once it gets to "Status" is gives the "No Data Received" error code. OBD2 is functioning properly. All fuses were removed before hand to allow for flashing. When truck came to me the PRNDL slider under the letters was not there. Tow/Haul will not function and trans temp gauge doesn't work. TCM is plugged in with no loose pins or connections. Truck feels like its running in the "HOT" table and will not shift as it should. When trying to get either V8 or V7.5 to respond it will get to checking status and error out yet via OBD2 it will flash the ECM back to back to back without issue. I am using the latest downloads and firmware/bootblocks as of today 08-23-22. Sound like a TCM issue? Also, for engine swap the VATS is disabled and full flashed into ECM before hand. Also allowed me to license ECM without a hitch also. I have a correct stock tune I also tried flashing and it will not even attempt as it will never get past checking status before erroring out.$101 Any help is appreciated.

[Cougar281]

Sounds like the class2 wire to the TCM may be broken somewhere.

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[TorqueMonster007]

Sounds like the class2 wire to the TCM may be broken somewhere.

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There was a U1000 or U1001 code present that was current for Class 2 Data Link but wasn’t sure if that’s because original motor was pulled and replaced?

[Cougar281]

I doubt it would be related to pulling the engine (other than possible harness damage caused during the swap). The fact that you had no indicator under the PRND12 and T/H & trans temp were non functional, and can't communicate with the TCM using efilive suggests that the class 2 wire to the TCM is broken somewhere. The odd shifts suggest that maybe there's also a J1939 issue (J1939 is used between the ECM, TCM and FICM). I'd say verify the data lines are OK before condemning the TCM. You should be able to find helpful schematics on gmupfitter.

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[TorqueMonster007]

I doubt it would be related to pulling the engine (other than possible harness damage caused during the swap). The fact that you had no indicator under the PRND12 and T/H & trans temp were non functional, and can't communicate with the TCM using efilive suggests that the class 2 wire to the TCM is broken somewhere. The odd shifts suggest that maybe there's also a J1939 issue (J1939 is used between the ECM, TCM and FICM). I'd say verify the data lines are OK before condemning the TCM. You should be able to find helpful schematics on gmupfitter.

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After a little more investigation all the pins were all different heights when unplugged from TCM. All of the pins didn't look to be seated all the way. Going to try and make sure they are all correct and check the Class 2 data bus and see what may be there.