Recently I replaced the motor in my 6MT 2003 350z, I also swapped a cd009 into it before doing the engine swap. I bought a good jdm low mile motor (automatic) and swapped my psp and ac into it. I kept my original wiring harness and used that, replaced both cam and crank sensors on the new motor. After getting everything in when I went to start it up the radiator fans kick on and goes into a "Fail Safe" mode. This also is keeping the fuel pump from priming, and the coils from sparking. Car will crank but not start. Originally we dove into the forums and found common issues with IDPM Boards and the relays, every relay, fuse, fusible link, BCM, etc is all good and has continuity. Nonetheless I replaced the IDPM board with an eBay one in excellent condition, problem still occurs. I pulled out the entire wiring harness and inspected for any shorts or breaks on the wires, all was good. I assumed maybe I cooked my ECM and that's why it was not communicating. Replaced ECM with exact spec replacement from my year and model car. Nothing. Spoke with the techs at Z1 Motorsports and they told me my wiring harness would be the culprit. So I once again removed it and replaced it with the exact same spec. Once all hooked up, still nothing. Fuel pump primes if you run a different power source, that isn't the culprit. All my grounds are intact, clean, and tight. Battery is fully charged. All testing has resumed with the original factory ECM, still it is not communicating. OBDII does not connect due to ECM not communicating. The car ran and had no electrical issue before replacing the motor. Any advice or suggestions appreciated, this is my first post on this forum. All wires and connections on the harness are accounted for and plugged into their correct spot.