Electrical Introduction -
As I've mentioned elsewhere, I fully intended to install the electrical, cooling and fuel systems necessary for my swap into the car while still running the stock drivetrain. It seemed like a way to approach a large project incrementally -- in terms of time and expense -- while minimizing the time the car was off the road. Ultimately, I was sucessful with the cooling system, got part of the way with the electrical and did nothing about the fuel before pulling the engine. My "part way" move with the electrical system was to take the main fusebox and main power leads (battery, alternator and starter) and mount them into the Datsun. This was pretty easy, just a short afternoon's work. The bonus to doing this was that the Miata has the battery in the back, so my otherwise stock Roadster had a rear-mount battery solution. Unfortunately, I pulled all sorts of "unnecessary" leads out of the guts of the main Miata fuse box, only to discover that they were not only necessary, but also documented solely in the $100 factory manual. After it was clear that I not only had no idea where things went, and had lost some of the OEM patch wires, I bought second, intact fuse box and started over with it. Even with a complete box, figuring out what wires went where (e.g. directly to relays, to the in-cabin fuse box, directly to sensors/actuators, to the ECU, etc.) took a fair amount of time, patience and flipping through 15 or so pages of half-assed Mitchell program Miata wiring diagrams. So far, I have created my own wiring diagrams for the ECU (stripped of unnecessary wires, mostly having to do with smog and safety devices) and the power circuit. I still need to finish the diagram that shows how the new Miata wires (including a retrofitted Miata cabin fusebox) mesh with the Roadster's non-powertrain-related wiring (lights, gauges and eventual audio). This, is really only a matter of redrawing how things connect with the new fuse box and making note of some other aspects of my non-stock harness, which I created about 2 years ago.
	This is my power harness diagram, based on the stock Miata fuseboxes, but stripped of any leads unnecessary to running the engine in the Datsun (stripped of smog devices, power assist devices and A/C). [UPDATED 8/18/08: final alternator hookup and gauges added]
	Here is the ECU harness diagram based on a '94 Miata harness with 5-speed, with all smog devices removed. So far, I've gotten the check engine light to give me some error codes, about the missing smog equipment, but it starts and runs fine. [UPDATED 8/18/08: Tachometer added]