1998 dodge ram 3500 5.9 not charging VIN 3B6MC3661WM257796

hey Paul, first i wanna thank you for all of your work that you have done and the videos that you have recorded, thats a lot of help,
so im having trouble with this dodge and im getting frustrated with it, so the customer was jumping a tractor with this pickup with the jumper cables on backwards and charged for a while like that, so another mechanic had the pickup there for a while and he said the fuel injector pump was out so he swap it from a 12 valve cummins engine and this is a 24 valve, and he tock the ECM out because he said it does not need it anymore, so the engine is running good but the alternator is not charging and i dont have RPM ether but i believe it comes from the alternator, so if i check the test procedure it says that it has to have power on the blue wire at the alternator with the engine running and that one comes from the PCM and it does not have power, i already check the power and grounds on the PCM and im getting power and ground to the PCM, and i checked that blue wire and its not shorted or short to ground, it seems like it is good, and i back probe it at the PCM and there is no power there, the test procedure says if there is no power at the blue wire then the PCM is bad, so i swap the PCM with a junkyard one and i stll have no power at the blue wire, do you think this PCM is also bad or am i missing something???