Straight Engine Swap, ECU Question...

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Straight Engine Swap, ECU Question...

Postby vash169 » Tue Jan 06, 2009 5:05 pm

This is a repost, as I do need to know the answer sooner than later!

I may be doing a JDM swap soon on my '91 185. My clutch is burned out, it had a questionable rebuild done on it about 3 years ago, and I don't want a whole lot of downtime from trying to fix up my existing engine.

I know a 90-91 engine can only be plugged into a 90-91 ECU, same for 92-93. I also know that as far as plugging in the ECU goes there's no difference between JDM and USDM. My big question is about the wiring relationship between engine, ECU, and the rest of the car.

If I was only able to locally source a 92-93 engine and ECU, would I be able to plug the body harness into it? In other words, is the only incompatibility between the 90-91 and 92-93 the engine harness?
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Postby Mafix » Tue Jan 06, 2009 5:16 pm

the engine is the same. just swap the wiring harness to your exsisting one. between the first and second run the ecu pinouts (and harnesses) are different.
the body harness is the same IIRC
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Postby vash169 » Wed Jan 07, 2009 12:33 am

Hmm I think I'll have to do that anyway, I'm just remembering now he might have sold off the engine harness separately. Bah, I was hoping to pick up the engine and ECU at the same time. Oh well, I may luck out and match the year anyway. It's good to know I don't have to fish around for the right harness if he doesn't have it, at least!
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Here's what I did:

Postby aubeone » Tue May 19, 2009 4:38 pm

Since the signals are the same, just occasionally located in a different pin configuration, it should just be a matter of repinning the plugs you have, or creating a harness adapter to correct the location changes between ecu's...that's what I did in my conversion from NA 165 to JDM 185.

Click on the ECU Conversion link in my signature to see what I did. There's a downloadable Excel Spreadsheet that shows the pin conversion for the ecu swap, and there is also a master list of all available ecu's for the 3sgte. Just check your part numbers and you'll be able to see the difference in pin-outs.

Also on that page, there is a second downloadable spreadsheet outlining the underhood portion of my conversion. Since I am using the stock 165 harness, I have to change the plugs for the Engine Control, Starting, Ignition and Charging circuits to the newer versions that fit the engine.

If you have any questions, let me know.
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