OBD2 does not communicate to the ECM

If the scan tool powers on then you have power and ground at the DLC. However, there is a separate wire that is used to communicate with the modules. Take a look at the wiring diagram. I suspect you have a wiring issue on the Red/White wire from the DLC through the joint connector to the ECM. Clearly I can't tell you where the issue is but I would just run a new wire from the DLC to the ECM and see if that re-establishes the scan tool communication. This is assuming the scan tool has worked on this vehicle in the past. If it has then I would just try it on another vehicle to make sure it is not the scan tool. If it works on another vehicle and it has worked on this vehicle in the past then run the new wire and see what happens.

Let me know if you have questions. Thanks

Sounds great. We will wait to hear back. Thanks for the update.