Hi all,
Need help id'ing this ecu. Label says:
3S (in large characters), under that: 226 AC740, under that: AI8-000 D34, next to that: 6802. Says it's made by Unisia Jecs Corporation in Japan. Came with an engine out of a '96 JDM WRX wagon auto, but pinout doesn't match any of the wiring diagrams. Help much appreciated.

TIA.

 

I swapped my ECU out last summer for a power FC, and I am pretty sure mine was a 3S. I can't check right now since I reinstalled it for the winter, but it sounds like you got the ECU for the M/T WRX instead of the A/T ECU. I have another book that would tell me exactly what that ECU is from, but a friend has borrowed and kept it for the past 3 months. The pic below is just the plug diagram for Subaru ECUs. The M/T is the OF-2, whereas your ECU should be of the OF-3 style. Hope this helps. Ill try to get that book back if you need more info.

 

My ECU looks like the OF-2 type. I have wiring diagrams for JDM WRX, but the wire colors just don't match up. Is there a big difference b/w mt and at? If you can shed any more light, I'd be eternally grateful, because this has been a bottleneck in my friend's swap. Thank you!

 

From what I know, the harnesses for MT and AT are similar, yet, they have enough differences between them that I was going to have to do a harness swap
(along with all the other stuff that a MT comes with) to convert a 4EAT WRX to a 5 speed manual. Also, if you have the OF-2 style ECU plugs, then it doesnt sound like you got the right ECU. If it turns out that your ECU will indeed not work, I happen to have one from a 1994 AT WRX. If your motor is an EJ20G (93 to early 96), then it should work. Also, I think there is a misprint in the book I have. It says the EJ20G ECU has the OF-3 plugs, but I am holding it right now, and from looking at it, it has the OF-1 style. I will compare it with the other book that my friend is returning to me.

I was just curious about what kind of swap you are doing to where you need to pay attention to the colors of the wires. I thought you just would swap the engine and harness and it would pretty much be a plug n play deal. Let me know. You can e-mail me direct. It would be faster.

 

what years did the OF-2 style ecus come in, im trying to identify the motor i have and cant seem to find anyone who knows for sure, i was told it was a V3 sti but then i heard it could be a V5 or V6. any info will help.