I have a 89 240sx that had the original sohc in it and im swapping a 5.3l lsx witha 98 pcm and harness no ac, no p/s. what i need to know is where i need to hook up power to the ls1 harness and/or where it comes from on the car i know i need to get the pcm programmed and stuff deleted but just not sure on what wires to hook where? any help would be appreciated thx!

While the 98 will get the job done, if you can find a 99+ PCM, I think it will be easier for you to find information and apparently the later years are more flexible and easier to tune...sorry I don't know specifics. If you can get the car to KY, we can take care of you, but if not, e-mail at oxymoron240 @ gmail . com and I think I have some 98 diagrams.

ok found what needs power etc for the 98 harness just need to find where it comes from on the 240 been doing some more searching im sure ill figure it out eventually just posted to see if anyone would know off the top of their head lol

There isn't one place it has to come from. You can pull from a few places. I am not familiar w/ the S13 like I am the S14, but I pulled almost all my power from the F3 plug...which is where the old engine harness plugged in for power. Once I found the pinout for it, I used an old KA harness and pulled out (acutally de-pinned, not pulled) the wires I didn't need and had a little power harness basically.

You will need a few sources for constant battery power and a few sources for switched power. A lot of it will depend on where you plan on mounting your ECU.

ok cool im pretty sure s-13s have the same "f3" plug might be pined different but ill get the pinout for it and i should be good to go thx for the help :-)