Are all 90-92 st185 usd/JP ECU interchangeable ?


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I assume the different part numbers won't work on our all tracs right?

Part numbers: 89661-20760 89661-20761 89661-2B290 are these interchangeable?

The 1992 all trac my bro has 89661-2B290 and a seller here sent me 89661-20761 and the car won't start with this Ecu.

Either the part is bad or the Ecu must be the same. Can anyone confirm this?



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89661-2b290 usd is the 1992 all trac Ecu that we need
89661-2b280 JP is the closest part number/Ecu I can find so far.

Do you guys think this will work?

Only noticeable differences:

26 pinout on the Jdm is missing egr? Stj? Ht?
16 pinout looks identical
22 pinout is missing #act pin is on the jdm which is not on the usa Ecu


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there are two versions of ecu for the gen2 3SGTE engine. Either will not start the other....but you have to swap a couple pins and it can happen. I think the same goes for USDM to JDM swaps.


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You have to repin the 90 harness to work in the 92 ECU. It's tedious but I haven't had problems after 9 years. Some cutting and splicing is needed because the some pins are bigger and won't fit into the plastic plug.


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Hi everyone, it’s been years but I have a 1990 st185 USD I’m having restored and it has a JDM swap gen 2nd Gen 3sgte. Every thing is running well except for 2 codes including code 71 EGR error which makes sense since the JDM engine is missing the EGR.

What’s the best way to fix this? Swap the intake manifold with a USD one or using the JD
m ecu 89661-2b280.

I believe the pins are both 26 pins. Will using the JDM ecu from the JDM having any issues? Thanks in advance!


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If the car was originally a California emissions car it had a temp switch in the EGR valve. If it was a Federal emissions car there's just a jumper in the harness for the switch connector. Harness (other than the jumper) and ECU are the same for all US spec (assuming the same revision). Pre revision is 90/91, post revision is 92/93.

If you're using a US harness and ECU you can just jump the switch connector. If you have a JDM harness and US ECU you can jump the harness at the ECU (you may be able to jump the harness at a connector, I forget which JDM circuit corresponds to the US EGR circuit).
Or you can swap in a JDM ECU. It will "bolt" into a US harness as long as it's the same revision.

JDM will give you a little more power, but I don't know how much of that you'll get with only 92 or 93 octane.

Those are basically your choices.


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Thanks for the reply! I’ll check the connectors but I assume it’s the connector to jump is the connector to the ECU? I also have the JDM same revision ECU I can try. The biggest concern is that the intact manifold on my JDM swap is missing the EGR. Since this is originally a California emissions all trac, I’m concerned about the visual inspection. I’m not even sure if Smog shops even check the EGR for functionality anymore tbh.


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Reviving the thread. What do you mean by jump the harness? Do you need to buy an adapter/harness or blocking out a pin in the ECU? Thanks in advance!


Active member
In broad terms all the cars have the same harness (ish). The ones with EGR plug into the EGR and the ones that don't have EGR just have a jumper connecting the two wires in that same plug. So to delete EGR or run a non-EGR engine you just put a jumper into that plug. Or trace it back in the schematics and bridge the connections somewhere else.


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So on my 1990 st185 USD harness and USD stock ecu disconnected and attempted to try my JDM 89661-2b280 JDM that came with my JDM 1991 engine and the car does not start.

I guess the 1990 USD harness is different from the 91 JDM ecu.

Can someone give me more details on how to jump the harness? Is there a part I can buy or best way to bypass the EGR code? Does a non Cali car with no EGR have stock harness to plug in? I don’t mind keeping the stock USD ECU with my JDM swap.


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There should be some threads with pics here on the forums for removing pins from a harness. I used to use a micro flathead screwdriver to do it. If you look inside the harness with a light you see there is a tab that holds the wire in. If you press the tab and pull from the back of the harness you can pull the wire from the connector and then move it to a new location. It will lock into place when inserted correctly. Just make sure you know which wire you are moving. You can confirm the wire color the st185 BGBs that are online.
one or two pins, yeah i'd probably just try to de-pin and move some wires around. If you're thinking you might have to do more though, I suggest getting a jumper harness like one of these (they're also out there on the internet elsewhere) and doing all of your cutting, splicing, or depinning here. You can limit the chaos to the jumper harness but leave the original harness in a baseline configuration.