Questions on 90 USDM model

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Questions on 90 USDM model

Postby OutToWinPAHC » Tue Jul 26, 2011 1:36 pm

I am doing my research on tuning options for my 1990 all-trac and I rather not piggy back it. My background is Nissan RB and GM LS series engines., so this is a very new animal to me I have found this here http://www.biststone.com/coyote-mr2/howtogen2togen3.html and I would like to use a Power FC. The issue is that this write up list 91-92 to 94-99 gen3 ECU, but I believe they are talking about 91-92 MR2 to gen 3, but I am not certain. I then found the extension harnesses which also say 90-99 MR2, 91-93 ST185, 94-99 ST205, is the 90 ST185 ECU and harness very different? For ease of converting back I think I would buy the extension harness and perform the pin changes there instead of the engine harness.

Does this wiring work for converting a 1990 USDM model to Gen3 for use with the Power FC or would I need to get a gen2 or gen3 MR2 harness first? Basically how do I take a 1990 USDM all-trac and convert for use with the SW20 power FC? All info is appreciated from this newb
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1990 ST185 All-Trac 54trim
1993 Nissan Skyline R33 GTS25T-M widebody built 60trim R34 NEO AEM-Series 2
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Re: Questions on 90 USDM model

Postby OutToWinPAHC » Tue Jul 26, 2011 2:36 pm

Actually AEM EMS list the 90-91-92 all-trac and 91-92 MR2 under they same EMS part number so it would appear the 90 all-trac is the same as the 91 MR2 ecu. I would like to re-confirm this but I think I will still convert from USDM to JDM Gen 3 with use of a SW20 stand alone. Hopefully I can reconfirm this.
1990 ST185 All-Trac 54trim
1993 Nissan Skyline R33 GTS25T-M widebody built 60trim R34 NEO AEM-Series 2
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Re: Questions on 90 USDM model

Postby Boo_Guy » Fri Jul 29, 2011 12:13 pm

Heres a diagram of MR2 and GT4 pinouts;
http://gt4.mwp.id.au/Electrical/All%203 ... iagram.png

My understanding is that the 89-91.08 GT4 ECU is the same as the 89-91.12 MR2 ECU

Then the 91.08-93 GT4 ECU is the same as the 92-93 MR2 ECU. Well the MR2 92-93 has a few more pins in use than the GT4's but when one wants to use a 92-93 MR2 ECU in a 92-93 GT4, that the extra pins just dont get used, without consequence.

Thats my understanding anyway, I'll be corrected if im wrong :P .


The diagrams have ECU part numbers on them that you can check against your own if you happened to have a car from around the time they changed the ECU's to see whether its a pre or post refresh. Not that it would effect you, but more as just an FYI.

Anyway hope this helps a little. 8)
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