Ok, here we go, the following guide, is my compilation of info from this board and others that I used to do the wiring on my friends Z. I made this guide to help others with what can be the most difficult part of any engine swap, even though it is quite simple, it can be intimidating, which is why so many people opt to pay serious cash to have the wiring harnesses done, when you really don't need to. So I deceided to put together a guide that goes though the process I used to get the RB set up and running. From the get go, let me say that you will need to know how do do some basic wiring, ie splicing, soldering, and have a decent knowledge of how wiring works, like reading a schematic and using a test light and multimeter. Now just because I said that don't think it will be any harder, these are simple things and if you can put in your own stereo and feel capable of doing this swap then you can handle this part too.
Next, the disclaimer, although this guide should get you running, missing something along the way or making a mistake, like not disconnecting the battery while doing something etc and frying your ecu or something similar is not my fault, so don't blame me if something like that happens.
I'll be trying to make this stuff as clear as possible, but I want this guide to evolve, so if you guys find any part unclear, need a better shot of a connection or whatever don't be afraid to ask, look at it this way if you have the question, then someone else will have it too, and by clarifiying I won't continiue to get that same quesition over and over adnausium.
Finally I want to thank all those that helped me, primarily Myron, Q, Zcarnut, Stony, and Matt Hutchens, and to the HybridZ crew in toto, since most of my info I gleaned from here, I just wanted to give back a bit and turn that info into and easy to follow guide. I will also try to make clear the differences between Z's and note the different ways that you can go with different Z's. The swap I did was an R33 RB25DET into a 75 280Z from California. I got the engine etc from a clip so I'll note what you need to have if you are getting an engine/tranny harness package. I prefer to pull my own stuff from a clip because you get to see the stuff before it is taken appart, and you will know the harness has not been cut in the wrong place and that all the stuff is there, but some people prefer to get an engine/tranny/harness package on a pallet and that is ok too, just need to get it from somewhere reliable. This is an RB25DET but a RB26DEtt should be similar, I haven't done that swap so you are on your own with the differences. I also suggest you print out one of the available ecu pinout diagrams availible on here to help and a schematic of the RB and the Z car will be helpful as well.
With that lets go. This first pic you see the general reason why this can be intimidating. This is a shot of the engine harness that covers running the fuel injection. For Those getting a engine/Tranny/harness package, which will here after be refered to as an ETH, you will want to make sure that you have all the harness off of the engine as it goes through the firewall with the gromet and the ecu plug, this should also contain the eccs relay, and the main fuel injection relay, (they are side by side near the ecu plug) you will also need the ecu, and the main white plug that the ecu/engine harness connects to the rest of the skylines in car harness. you should preferably have about 3 feet or so of wire off the back of the white connector that would normally go to the ignition switch and other things inside the car. So if you pull it from a clip get that, if you get an ETH request it from who you are buying if from you can do the wiring without the white connector, but I found it made locating the wires and routing easier. You will also have a separate harness that goes to the tranny, alternator, starter, main hot, and IAC valve, you can do the wireing again without this separate harness and hook up the Z stuff on this side, but I found it easier to use the skyline tranny harness and splice it into the Z harness.
