I've used the search function a bit today (work was slow at times, I got bored a few times..) and the results are very conflicted. And based on USA cars. Anyways, does anyone have an explanation for the N___ numbers on the factory JDM FD3S ECU?

Specifically,

-N3A7-XXXXXXXX is JDM FD3S Manual Trans?
-N3A8-XXXXXXXX is JDM FD3S Auto Trans?

What about all these N3A1, N3A2... N3C1, N3A3 numbered others in between?? What are they for?

I know my car, being 1992 JDM auto, has an N3A8______ ECU. I've read that due to a factory recall, there is an upgrade ECU, N3A8_______B which solves the hold light flashing recall error.

I'm looking at what ECU I would go in search of, if my car ever gave the flashing hold indicator error. So far I've found no information, none for sale and no way to identify if my N3A8 ECU has been replaced/upgraded in the recall or not.
Plus, as cheap as they are, having a plug n play spare handy would be nice. None of my other FDs are compatible, as they are all manual trans cars.. And frankly, all these N numbers are confusing me

 

While I am not a FD Expert, having every parts catalog since 1967 does give me some room to gloat

N3A7 is for the first run manual FDs (up to 8/5/1992 build date), N3A8 being for the first run automatics (FD3S-1xxxxx, up to 8/5/92). 8/5/1992 was when Revision B was implemented at the factory, the one you mentioned correcting the flashing Hold light. Revision C came about on 8/24/92 for the N3A7 Manuals and 8/28/92 for N3A8 Automatics. Second-run cars, chassis number FD3S-2xxxxx (production beginning in 7/93), got Revision C from the start, all the way through December 1995. The N3F1/N3F2 ECUs were rolled out on 12/28/1995, beginning with FD3S-4xxxxx (AKA Series 7).

If you'd like to post your chassis number, I can run a build sheet on your car to see what it came with from the factory.

IIRC, an Automatic ECU can be used in place of a Manual one. One of my best bud's FDs began life as an N3A1 Automatic 93 untill we did a AT to MT conversion on it, retaining the original ECU. This was several years ago and the car in question has seen a PowerFC since then, so I am not sure how well it worked. There should be some information in the Third Generation FAQ to get you in the right direction.

As for gaining an understanding about what the individual numbers mean, I'm still working on it but here's what I have so far with the FD as an example:

1st Digit: Engine Family, N=Non-Piston Engine (Rotary)
2nd Digit: Last number of displacement in Liters, 2=12A, 3=13B, F=20B
3rd Digit: Version & Options, A= S6 USA/JP, B=S6 Euro, C=Revised S6 USA, etc
4th Digit: Region & Transmission, 1=USA MT, 2=USA AT, 3=California MT, 4= Cali AT and so on

This data is by no means complete, but the pattern is validated so far based on the US-spec 1989 626's F2 and F2 Turbo ECUs (F201 through F206 and F220 through F226 respectively)

 

Wow... Thanks so much!! My email never actually notified me that anyone had replied to my post, and I just stumbled back here. Stupid forum notifications... Anyways, will send you a pm tonight buddy!

 

Hey Akagis, new member and ran across this thread. Can't DM you yet so thought I'd reach out here as I sorely need a build sheet or wiring diagram for my JDM '92 FD3S with N3A7 ECU. A wire has been de-pinned from the yellow ecu connectors and I can't find any pinouts that match my car.

Can I reach out to you if you have any references or build sheets? I've searched the forums and Google to no avail.

 

My apologies as I've been ludicrously busy over the last 6 months with the Eunos Cosmo and just now got a chance to catch my breath. On the plus side, I do have the diagrams and pinouts. Send me your VIN and the pertinent info and I'll see what I can dig up. There were 3 different version of Series 6 FDs in Japan, and I want to make sure I give you the correct info.