After many rough miles/years on my 2002 2.0 M/T Chevy Tracker, it was time to rebuild... well... everything. The engine still runs but smokes, the transmission leaks, the front differential went out sometime last fall and my rear diff started sounding like a meat grinder. Luckily, I found an entire drivetrain, frame and all, from a 2003 2.5L Automatic that had been rolled. The body was pretty crunched but all the underneath goodies looked perfect. It started and drove fine, once you pried open the door. It’s even low miles at 57K. So I thought as long as I painstakingly remove all the wiring harness and ECU this would be an easy swap. Just set my body on the new chassis, fish the plugs back through the firewall and plug in the ECU. This has NOT turned out to be the easy swap I thought it was going to be. I mean the body was easy enough. But there are a couple of significant differences between the two harnesses. The first thing to overcome was getting signal to the solenoid. I traced the wire back from the solenoid to a three pronged plug near the under hood fuse block. I have a 2003 2.0L auto handy for reference but this must be specific to the 2.5. No problem, I just jumped the signal from the wire in the dash bundle as it exited the firewall. Next was the fuel pump. My 2002 body harness has one less wire going to the fuel cutoff switch than the 2003 chassis. No problem, I just hot-wired the fuel pump relay. (Don’t worry, this is just a temporary solution). It cranks, it has fuel to the rail, but the injectors still won’t open up. I know that little three prong plug has something to do with it, but the donor body is long gone and I don’t even know what I’m shopping for. As I was closing up shop for the evening, I realized I also don’t have the IAT. No provision for that on my harness. Is that also a part of this naked plug??