Hi my name isXXXXX
I feel your frustration with this kind of concern. You are correct, the concern is with the Class 2 communication. Unfortunately this is one of the most difficult concerns to Isolate.
Any one of the modules on the class 2 line can be the culprit. You have a good start in going to splice pack 205 , and isolating it down to a BCM or PCM.
Reprograming does not correct a hardware issue with a module witch is usually the case in these matters.
If I were at this point I would check or rerun the communication line to the modules first.
If that did not correct and I did not find a definite short to ground, Next make sure there are no after market devices hooked in any where. Connections to data sources powers and grounds to modules will make them do weird things. But I don't think that is your concern here.
I would replace the BCM they have had more issues than the PCM. Plus the BCM is responsible for the body functions that your having troubles with.
Look around the left inner fender for the most likely spot for the communication line to be shorted that goes to ECM. It is most exposed and I have found allot of problems in that area.
Hope this is the info you were looking for. HAL
Yes I can thats not a problem.
The ECM should be located on the front left inner fender. Follow the harness up to the under hood fuse block. This is where I find most wiring issues. The harness will go under the UHFB and into the vehicle though the pass through grommet lower left of fire wall. It comes into the vehicle and up and over the emergency brake pedal. ( this is another location to inspect the harness. The BCM should be left of the steering column, or just below the column.
All you need to do is make sure the harness is not shorted to ground. Go to the splice pack as you have already done. find the wire to the ECM and BCM. Unhook the BCM and ECM and ohm out the wire. If you have continuity to ground then the circuit is shorted. If not then it is the module. This is exactly how I have to diagnose these type of problems.
Hears the catch. the condition MUST BE PRESENT to find it. As i stated before these types of concerns are very difficult to isolate unless they are hard failures.
If you need wire colors or terminal locations Let me know.
PS the reason I said replace the data circuit is because if it is shorted , it is sometimes easier to just replace the wire that it is to locate the short. At least it is for me.
Hope this info is what your looking for.
Your welcome, and thank you for using just answer.
Thanks again Hal