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97 HARD TOP
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Discussion Starter · #1 ·
okay first and foremost i am swapping a jdm 2jzgte supra motor into my 97 na supra. like a idiot i wasnt thinking and cut my old na 5 speed harness in several places. so to make it easier when i combine both the na harness and jdm harness for my swap i was planning on just buyinh a new 97 na harness from the dealership which sales for about $950. now i found a 94 na auto harness for sale for a lot less. my question is, is it possible to use this harness? i think the 97 is a obd2 and i though the older models were obd1. but if im cutting the ecu plugs off for the jdm one to go on does it matter? also same with the auto transmission clip? if mine was originally a five speed can i just cut the auto one and put on the jdm 6 speed clip? sorry for the noob question, just trying to save money if possible. thanks
 

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Definitely just get a TT harness. It will save you alot of trouble. You can run the JDM ECU on the TT harness with only minor mods. As for the fusebox, what I did was buy a new TT body side fusebox connector from Toyota and swap them out. The NA connector pins fit into the TT plug, you only have to add one extra wire for the fuel pump.
 

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Save yourself the trouble and get the tt harness. Also get an AEM extension harness which is like the Fields extension harness that way you don't butcher up the oem harness when you have to cut or splice things.
 

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97 HARD TOP
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Discussion Starter · #6 ·
jonoturbo- okay you say that the jdm ecu will plug into the usdm tt harness with just a few minor mods..care to explain the mods? wouldnt it be easier to just cut the ecu plugs off the jdm harness and put it on the usdm one? or are the minor mods eaiser then that? also if i read this correctly. the plug/clip that is attached to the na fuse box i should replace it with a tt one? and where does the extra wire that you refered to goto?

[email protected]-i see youve done the swap as well. the aem extension harness is a good point, thanks for reminding me about it, i checked their site and they sell ones for the jdm and usdm supra for our year. if i run a usdm harness but jdm ecu, likes everyone has said i should do which extension harness should i buy then?

i appriciate all the feed back, it doesnt seem like doing a wire conversion would be all that hard, just time consuming, i just want to make sure i know everything that needs to be done before i start. but if you think it would be easier to have a company that can do it right the first go around because you used them before just lkm who it was and pricing as well as turn around time was for you. thanks again
 

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I could make you a harness for cheaper than the cost it takes to buy a new harness. A new harness is cool but realistically it's a complete waste of money and still needs modification because of the map v maf issue.

Depending on how cut your JDM harness is the easiest option is to use wire from the NA harness to extend the JDM TT harness. Take the plastic shielding along the firewall from the NA harness and put it onto the JDM harness. You'll also need to take the 3 pin fuse box plug off the NA harness and graph it onto the TT harness.
 

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97 HARD TOP
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Discussion Starter · #8 ·
ryeno -hey man, i was hoping to see you post in here, i talked to you a while back about having you do it. when i cleared my inbox i couldnt remember how to spell your user name to contact you again so i created this thread. yeah the map vs maf issue was another thing i was worried about.but if you can just use the jdm harness and use the extra wire from the old na one that would be great. either way when it comes time for me to get this started i still want to use the aem extended harness so that it will be easier when it comes time to splice in all the guages and stuff.
 

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97 HARD TOP
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Discussion Starter · #10 ·
the aem does but you wont have to worry about that part, if you can still do the main harness that would be great. the extended harness plugs in the stock harness. i would post a picture of it but my work computer wont allow me to. you dont have it listed in the above picture. just google "aem extended harness" to get a idea of what im talking about but it doesnt have anything to do on your part.
 

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jonoturbo- okay you say that the jdm ecu will plug into the usdm tt harness with just a few minor mods..care to explain the mods? wouldnt it be easier to just cut the ecu plugs off the jdm harness and put it on the usdm one? or are the minor mods eaiser then that? also if i read this correctly. the plug/clip that is attached to the na fuse box i should replace it with a tt one? and where does the extra wire that you refered to goto?
Depending on what you want to run you may only have to change one thing on the USDM harness to run a JDM setup, and that is run the two wires for IAT from the MAF plug over to the intake manifold where the IAT sensor is on the JDM engine. If you want to run aristo 440's, you will have to bypass the plug for the resistor pack. That's it, its really not much work at all, and you end up with the ability to run USDM ECU's (if you swap the IAT wires back), JDM ECU's, and either high or low impedance injectors.

A new harness does cost plenty of money, but after seeing the condition of several used ones, it was worth the peace of mind for me.

As for the fusebox plug, the extra wire you have to add is for the fuel pump, the TT system has a separate circuit to power the pump where the NA does not. Basically you tap the extra pin into the existing power wire coming from the fuse box.
 

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I suppose I took the harder route by trying to wire a NA harness into an Aristo one, but about 10 hours into making my own harness I got pretty sick of it. Extending a harness or rewiring the body connectors to match up with your car is one thing, adding in the entire alternator and fusebox loom and moving all the igniter wiring is another.
 

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Definitely just get a TT harness. It will save you alot of trouble. You can run the JDM ECU on the TT harness with only minor mods. As for the fusebox, what I did was buy a new TT body side fusebox connector from Toyota and swap them out. The NA connector pins fit into the TT plug, you only have to add one extra wire for the fuel pump.
Jono can you expand on this a bit. This is the info I was looking for a few weeks ago. I remember someone had done this but I did not remember who. :)
 

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I suppose I took the harder route by trying to wire a NA harness into an Aristo one, but about 10 hours into making my own harness I got pretty sick of it. Extending a harness or rewiring the body connectors to match up with your car is one thing, adding in the entire alternator and fusebox loom and moving all the igniter wiring is another.
:lol: Dude you can just repin almost 95% of everything. The only thing you need to add is 12V supply for everything.
 

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Jono can you expand on this a bit. This is the info I was looking for a few weeks ago. I remember someone had done this but I did not remember who. :)
I went into more detail up a few posts in post #13. To run the USDM harness on a JDM setup you only need to move the IAT wires in the harness.

:lol: Dude you can just repin almost 95% of everything. The only thing you need to add is 12V supply for everything.
If you had a JDM supra harness yes, if you have an Aristo harness like 90% of the engines out there you won't have any wiring or connectors for the fusebox, alternator, etc. The entire 3rd ECU plug is missing from the Aristo engine harness. This is because in the aristo all that wiring runs through the body harness, and in the supra its in the engine harness.
 

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Ah, well then yeah, you're alot closer to being able to use the harness than most guys. I thought for some reason you had an Aristo. You probably don't even need another harness to patch yours unless its damaged then. Just extend the harness, swap the fuse box plug, and go.
 
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