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Discussion Starter · #1 ·
Hey everyone im looking for some help and any inputs would be greatly appreciated. I just recenty bought my first supra it is a 95 tt 6 speed but i bought it with no motor or trasmission. I picked up a jdm 2jzgte and 6 speed and am putting it in the car I have had some experince with car wiring so for now I just decided to extend the jdm harness and use that till I have decided what direction I would like to go with the car. I have extended all the jdm wiring harness and am using the jdm ecu but for some reason when I go to start the car I get nothing at all. I have checked grounds, tested the ecu to see if it is getting power which it is , checked clutch switches, fuses, relays and have looked at a lot of threads on here trying to get diffrent ideas. I read on here that some people on the orange and gray connector down by the ecu had to switch some of the pins around to make them work I was just wondering if anyone knew if this is true and if anone knew what pins or where I could get a diagram of the jdm and us pinout for these conectors.
 

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We need some more details...like what happens when you turn the key to ON? Does the CEL light up? Does the charge light come on? etc.
 

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Discussion Starter · #3 ·
When I turn the key to on all of the lights do come on I noticed some triangle light in the middle of the dash come on not sure what that symbol means . I know that the battery light does light up not sure if thats the same as the charge light but all my lights come on like taillights headlight etc. and they can be left on with out them diming.
 

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Try to hook a wire directly from B+ under the diagnostic connector under the hood, its right off the main harness against the firewall,
put a wire from that B+ to the battery postive, attemp to start vehicle, if it starts you have a connection problem to EFI circuit opening relays
I would also check the orange connector where the ecu is. I know it plugs in , but you have to latch it down with a hook, meaning you have to
pull on it to lock it all the way in...Hope this helps
 

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Are you using JDM or a USDM ECU? JDM engine will not run on a USDM ECU. If you are using the JDM engine and harness you need a JDM ECU. You can make a JDM engine work with USDM ECU and harness but it requires several modifications like MAP to MAF, igniter, injectors, etc. The JDM engine is similar (same short block) to USDM but lots of differences that make it not a straight forward swap.
 

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Are you using JDM or a USDM ECU? JDM engine will not run on a USDM ECU. If you are using the JDM engine and harness you need a JDM ECU. You can make a JDM engine work with USDM ECU and harness but it requires several modifications like MAP to MAF, igniter, injectors, etc. The JDM engine is similar (same short block) to USDM but lots of differences that make it not a straight forward swap.
question for you. will the jdm motor run using the usdm harness and usdm ecu, also will it run with the usdm harness and jdm ecu taking in consideration of moving the pins around) im in the same situation with my 97NA. i bought a jdm SUPRA motor and trying to figure out my options when it comes to the wiring thanks
 

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question for you. will the jdm motor run using the usdm harness and usdm ecu,
Assuming you also have the USDM MAF, USDM 550cc low impedence injectors, and the USDM fuel injector resistor pack...Yes!

also will it run with the usdm harness and jdm ecu taking in consideration of moving the pins around) im in the same situation with my 97NA. i bought a jdm SUPRA motor and trying to figure out my options when it comes to the wiring thanks
If the motor came with an ECU/harness, then just run the JDM ECU and JDM harness (after you extend it) and call it a day. You'll also need to swap in a turbo tachometer since you're NA (distributor signal vs CPS signal).
 

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yeah ive been trying to find one for awhile now. i now a few other things need to be changed so all the guages and fuse box works the correct way. nice mk3 dont think ive seen your car around any of the meets i ever went to?
 

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Discussion Starter · #9 ·
I am using the jdm ecu. For some reason it is not getting any power at all to the starter when I turn the key. I think there is something diffrent in the orange gray and white connectors between us and jdm.
 

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I am using the jdm ecu. For some reason it is not getting any power at all to the starter when I turn the key. I think there is something diffrent in the orange gray and white connectors between us and jdm.
there might be if the usdm one had a factory alarm or something and it defaultly deactivates the starter until the alarm is killed.

thats the only thing i can think of atm. but my car is jdm RHD, and the only things different are directly related to steering.
i even have a LHD hatch and the wiring is the same on that as RHD even though the wiper is on the opposite side. so what im tryin to say is that most of that wiring is identical.

1) when i wired a USDM aem ecu plug n play, the only thing i did was the same thing USDM people do. splice map sensor to map sensor wires (which was easier because jdm harness already has a map sensor on those wires.) and wire the IAT sensor to the 2 IAT wires, which are the same colour as USDM and i even used a help article for doing it on a USDM car because it was the exact same

2) the USDM and JDM wiring harness are the exact same except the JDM harness doesnt use the ecu input for MAF sensor, and the o2 sensor inputs are slightly different i believe, and the usdm harness has a resistor box near the injector output wires.

if you compare the two different ecu harness's you will find the pinouts are the same.

for example if pin 20a on both ecu's are both for the ignition/starter, and your car doesnt crank over.. then there is a problem between pin 20a and the starter.
in which case i would do some extensive electrical testing with a test light and multimeter, etc.

so based off my experiences i would be able to run a stock USDM engine by adding a MAF wire and making minor alteration to o2 sensor(s), and adding a resistor box for injectors.

but ive never swapped a motor in the supra so i cant say for sure :)



good luck though man, its probably going to be a simple little wiring anomoly and she will fire right up.
 

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yeah ive been trying to find one for awhile now. i now a few other things need to be changed so all the guages and fuse box works the correct way. nice mk3 dont think ive seen your car around any of the meets i ever went to?
It hasn't been out much in the past 1.5 years mostly due to being laid off from work while I was forging the 7M's bottom end for my new goal of 550rwhp. I just recently swapped in a 2JZ with plans to go single with my SP63 next year. I'm planning on attending the Castle Rock Toyota meet at the end of this month too. You a member of coloradoracing.net?

2) the USDM and JDM wiring harness are the exact same except the JDM harness doesnt use the ecu input for MAF sensor, and the o2 sensor inputs are slightly different i believe, and the usdm harness has a resistor box near the injector output wires.
JDM O2 sensors are 3-wire and USDM are 4-wire.
 

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Discussion Starter · #12 ·
Hey evreryone I just wanted to say thanks for all the inputs I found out the problem last week. It turned out to be that my us body harness had a clutch saftey switch wire in the grey conector by the ecu that normally would go to the ecu and allow it to let power go to the starter when the clutch was fully engaged but the jdm harness did not have the wire comming out and connecting it to the ecu so it was just acting like the clutch was not engaged. I re connected it and it fired right up. But one more question for anyone with a jdm supra do they have clutch saftey switches or not?
 

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No they don't the auto jdm is the only one that has the neutral and park switch which wont let you start the car unles in these positions. If you are manual then the car will start while in gear or not, with clutch up or down.
 
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