Recently bought HPTuners for my own project, but had to use it for the first time helping my brother with his engine swap.
Car A is a 2012 Caprice that he wrecked. Motor already had DOD delete, Cam, CAI, and a tune from a guy in Louisville, KY.
Car B is a 2012 Caprice roller that he bought recently.
Pulled motor and tranny from Car A and dropped it into Car B, adding some Kooks headers in the process. I was able to pull the tune, and turn off VATS. Car still had a P0513 Engine Immobilized code that I couldn't get to clear. We started the car multiple times while we traced down a couple loose hoses and connections. He was able to drive it home (15 miles) the next day. The following day he went to move it and it won't even turn over. Pulled the code and it is a U0100 Lost Communication with ECM/PCM. When I hook up to it with HPTuners it doesn't see the ECU at all, only the TCM.
We have checked all the ground connections that we can find, and cleaned them. Have unplugged and reseated the ECU connections. Have left the battery disconnected for 60+ minutes at a time. The fuses all test good in the underhood fuse box.
What else is there that we should check? Or did the security system somehow lock us out of the ECU?