JDM N374 Harness? What is the 3rd Plug For?
 

I just dropped the motor in my car for the swap. I just found several problems I didn't count on. It is an 86(s4) and I have an S5 T2 Engine. The dash Hanes plud is different, and has 24 wires instead of 22(I need the plug as well for thew (22), but the problem I really need addressed is, what is the 3rd Plug on the Engine harness that fit through the wall to the ECU. 2 Plugs are for the ECU, but I don't know what the 3rd is for. Also, where can I get wiring schematics or the pin reading(more importantly) for the dash to ECU Plug(24-S4 & 22-S5), and what do I do about the 3rd plug. I appreciate all the help I can get. Thanking you in advance.-Blake

there should be some plugs up in the side of the car closer to the firewall hole... i had a really hard time w/ it myself.

I will try to check on that thanks. What are the chances that it will be thewrong plug being an S5 in an S4 car. What do I do about the Dash harness and plug problem?

you should have read this first.... this outlines doing the s5 turbo in s4 swap.
http://www.rotaryresurrection.com/2n...o_s4_swap.html

there is something to be said for doing proper research before you start on such a large project. The wiring is very different. The article above is quite good and that site also has many other documents that are very good to read.

LUCIU$ in the following thread explains how you can use a series FIVE EM harness and ECU, on a series four car: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/s4-na-s5-jdm-turbo-conversion-405617/

His name is, again, LUCIU$.

Others have done it, but my memory fails as to the name. Someone, somewhere in the Caribbean.