gerrb

iTrader: (34)

MKIV TT / NA Wiring Diagrams



Alternator Connector
Pin 1 of Alternator Connector goes to Pin 34 of the II1 Connector
Pin 2 of Alternator Connector goes to Pin 23 of the II1 Connector
Pin 3 of Alternator Connector goes to Pin 2 of the EA3 Connector

Starter Connector
Pin 1 of the Starter Connector goes to Pin 1 of EA3 Connector

EA3
Pin 1 of EA3 goes to Pin 1 of the Starter Connector
Pin 2 of EA3 goes to Pin 3 of the Alternator Connector

EA1
Pin 3 goes to Pin 77 of the 80 pin ECU Connector & to ( Pin 9 of the IJ2 Connector & Pin 5 of Park / Neutral Switch (Auto Transmission Cars from Factory)) OR (Pin 2 of the IJ1 Connector (Manual Transmission Cars From Factory))

II1
Pin 23 II1 goes to Pin 2 of the Alternator Connector
Pin 34 II1 goes to Pin 1 of the Alternator Connector

IJ2
Pin 13 of IJ2 goes to Pin 6 of the Park / Neutral Switch (Auto Transmission Cars from Factory)
Pin 9 of IJ2 goes to Pin 5 of the Park / Neutral Switch & to Pin 77 of the 80 pin ECU Connector & to Pin 3 of EA1 Connector (Auto Transmission Cars from Factory)

IJ1
Pin 2 of IJ1 goes to Pin 77 of the 80 pin ECU Connector & to Pin 3 of EA1 Connector (Manual Transmission Cars from Factory)

Park / Neutral Switch (Auto Transmission Cars from Factory)
Pin 5 goes to Pin 9 of the IJ2 Connector & Pin 3 of the EA1 Connector & to Pin 77 of the 80 Pin ECU Connector
Pin 6 goes to Pin 13 of the IJ2 Connector

NOTE :

a) For those who originally have an auto transmission car and are converting to a manual transmission , you will need to jump pin 5 & 6 of the Park / Neutral switch which is like connecting Pin 13 and Pin 9 of IJ2 . If you don't do that , your car is not going to start because of that Park / Neutral Safety switch which will not be activated because you don't have an auto transmission anymore.

b) The alternator connector is part of the 2jzgte harness on the MKIV just like that of the SC300.

c) The beauty of going through these diagrams at this point is if you miss something along the process, there is a possibility that you will catch it.

d) When you see an arrow on a diagram and numbers in parenthesis , the numbers in parenthesis tells you the page and section where that diagram goes or comes from .

e) Updating your Body Plug Chart helps you see what is already filled up on your body plugs.


I WILL POST ALL THE WIRING DIAGRAMS HERE . Go through them and look for those Body Plug Pin / wires we haven't covered. When I have more time, I will go through them and write them down.

gerrb

iTrader: (34)

gerrb

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gerrb

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END OF SUPRA MKIV WIRING DIAGRAMS

gerrb

iTrader: (34)

RESERVE for HARNESS FINAL CHECK - pictures

Once I am all done with my harness , having wrapped it all up. I usually take my CHARTs and redo the connectivity check one more time. I know it is redundant but I know it will save me a lot of trouble later on. That process should take me an hour or less.

gerrb

iTrader: (34)

Part IV : CONNECTORS PART NUMBERS (COURTESY of CURT from ELMHURST TOYOTA)

90980-11400 Starter
90980-11349 Alt
90980-11246 Coil
90980-10532 Oil Level
90980-10711 Tps
90980-10896 Efi Resistor Male
90980-10897 Efi Resistor Female
90980-10947 Crank Sensor 2 Pin
90980-10947 Cam Sensor 2 Pin
90980-11062 Efi Temp 2 Pin
90980-11077 Fuel Pump Harness 5 Pin
90980-11151 Ignitor 12 Pin
90980-11152 Ignitor 4 Pin
90980-11166 Knock Sensor
90980-11362 Fuel Pump Ecu
90980-11428 Dash Temp 1 Pin
90980-11154 Stock Injector 550's
90980-11028 main o2 harness side
90980-11027 main 02 sensor side
90980-11363 oil switch pressure
90980-10799 active spoiler
90980-10933 seat heater
90980-10957 trac 93.5-96
90980-11535 trac 97-8
90980-10801 headlamp level
90980-10801 lh pw switch
90980-10789 rh pw switch
90980-11236 aux fan 93.5-96 [motor side]
90980-11235 aux fan 93.5-96 [ harness side ]
90980-11143 speed sensor on trans
90980-11051 V160 reverse switch
90980-11077 fp hanger
90980-11080 fuel pump +/- under hanger
90980-11079 tank sending unit
90980-10943 a/c h/p switch
90980-11622 3 pin harness side 97-98 turn/park rh side
90980-11078 5 pin connector on FP hanger
90980-11144 iac motor
90980-10942 ac plug 4 pin
90980-11555 orange foot well 38 pin
90980-11562 white footwell 16 pin
90980-11469 gray footwell 20 pin
90980-11413 fuse box upper
90980-10897 fuse box lower
90980-11025 iat
90980-10841 map
90980-11156 evap vsv
90980-11195 diagnostics 23 pin
90980-11144 trac motor
90980-11156 egbv vsv
90980-11149 iac vsv
90980-11149 egc vsv
90980-11156 wastegate vsv
90980-10843 ign condensor
90980-11002 2 pin rack plug
90980-11450 lh dash warning indicator
90980-10957 93.5-97 cruise swith @ squib
90980-11964 tundra 4 pin alt plug
90980-11148 2 pin glove box light
90980-11317 maf/ af mete
90980-11237 a/c fan motor
90980 -11235 temp sensor in radiator
90980-11245 3 pin harness side for 93.5-96 fog light cap
90980-11162 vvti valve 2 pin
90980-10957 93.5-97 cruise switch
90980-11214 ecu plug 80 pin
90980-11215 ecu plug 40 pin

gerrb

iTrader: (34)

Part VI : QUESTIONS & ANSWERS

I am posting here the questions that have been asked on my other thread so other's can benefit. Take note that the answers are my personal views and opinions only. They may not necessarily be right or the same as how the PROs will answer them.

Once I am done posting all the Q&A from my other thread and I have written the Conclusion , (though I need to go back and edit some posts still) anyone can feel free to ask their questions or write their comments . Questions can be answered by anyone who knows the answer , so feel free to chime in to answer. Remember this thread is to help the community and not show that you know more or better by being a ?ickhead. Nobody had been born with all the knowledge. Somewhere , somehow we have acquired it through whatever means so please be nice in answering or commenting.

Q) I know you are doing a 2jzgte harness for the Lexus SC300 / SC400 . Will it be the same for the Nissan 240sx ?

A 2jzgte swap is a 2jzgte swap regardless of what car. The 2jzgte engine harness needed to run the 2jzgte engine is the same. So whatever car you are building , you just need the BODY PLUGS of that car so you can connect the engine / drivetrain components and ECU to other components of your car like ignition (so you can start the engine ), engine cluster and gauges ( coolant , oil level / pressure , AC control , etc ) . So having the diagram of your particular car helps a lot !


Q) So if I have a 2jzgte harness done for the SC300 already , can I use same harness into an SC400 with a 2jzgte swap OR VICE VERSA ?

One thing you need to take note is years of your cars and configuration / setup the 2jzgte harness was made for and your current 2jzgte setup. There maybe slight differences but I would say not much.


Q) I have read someone uses the SC300 harness as his starting point to build the 2jzgte harness . Wouldn't that be better since my car is an SC300 ?

As I have said previously , it is a personal preference . I don't think there is right or wrong for that matter. What is important at the end of the day , you got a working 2jzgte harness for an SC300.

There is a reason though why I prefer to start with the Aristo 2jzgte harness as my base. True I may have an SC300 car with the 2jzge engine . Since I have decided to swap the said engine with the 2jzgte engine and I am building a 2jzgte harness , I might as well start with the 2jzgte harness since it is the harness that came with my 2jzgte engine and it should have everything necessary already done for me to get the car running. All I need to do is clean it up , extend wires that need extending and get all the body plugs in there that are unique to the car I am installing the engine which in this case the SC body plugs.


Q) Can I just not get a MKIV TT harness and use it on my Aristo 2jzgte swap on the SC ?

The Supra MKIV TT even if it has a 2jzgte engine is a different car from the Lexus SC. Thus it has different body plugs. True , the wiring to get the engine running is there but it still needs modifications. You won't need to extend the wirings though. Also take note , USDM Supra MKIV with 2jzgte are slightly different from a JDM 2jzgte whether from MKIV or Aristo. So indeed may need some modifications. One example is USDM 2jzgte harness has MAF while JDMs do not. Some sensors may have different connectors.

Q) Do you really need to replace the 4 pin igniter connector on the left when what is broken is just the outside cover / casing as pictured ? After all it looks like connections would still be alright since the lock is intact .



Yes and No I would say . Yes I strongly recommend it if funds is not a concern and to protect the component better from any dirt or liquid splashing into it. No if you have no more money to replace it but need to get the car running but I would suggest that you wrap that connector WELL with electrical tape as pictured below or a lot even better with more electrical tape . You have to make a judgement call on that matter. IF you think not replacing it will give you problems due to various factors , then you got to replace it.

IF any lock of a connector is broken I would strongly suggest replacing the connector. There is a lot of vibration when that engine is running. Any loose connector can potentially give you problems or even hard to find problems .. gremlins I would say. So eliminate possible loose contacts on connectors by replacing them if their locks are broken. That is what the locks are for... to keep them in place and prevent as much as possible loose connections.



Q) There was a time I got a 2jzgte harness done for my Lexus SC300. At that time I was looking at stock auto transmission so the harness was for an auto tranny. But now , I have decided to go manual transmission , do I need another harness done or can I use same 2jzgte harness done with auto transmission wiring ?

Simple answer is yes , you can use the same 2jzgte harness done for auto tranny for your manual transmission with a very minor modification. The auto tranny connectors on that harness won't be plugged anywhere since you don't have an auto tranny. But a slight modification on a connector that is needed for the manual transmission would have to be done... really minor.

One thing I was told but never experienced so you need to verify yourself please , you can run your 2jzgte engine with manual transmission with a 2jzgte auto tranny harness and Auto TT ECU . IT IS NOT OPTIMAL though since an auto ecu takes care of auto tranny shift points does fuel trim and timing are affected . Since you don't have an auto tranny being controlled , the way your engine runs won''t be the best. But for the sake of just test driving if you don't have a MANUAL 2jzgte ECU yet , I guess its a good thing to know. But please don't quote me on this since I have never experience really running a car that way on the street. BUT I have started a car with 2jzgte V160 tranny with auto TT ECU just to check if there is a problem with my 6 speed TT ECU. And no doubt that engine will start if its a good ECU.

On the other hand , if you have a 2jzgte harness for a 6 speed / manual transmission , you will never be able to use it with a 2jzgte engine with auto transmission without modifiying it. Some work needs to be done to include all those wirings / connectors so the auto transmission can be controlled by your Auto TT ECU. And no you cannot use a 2jzgte 6 speed ECU to controll a 2jzgte engine with auto transmission. It doesn't have those internal circuitry on the ECU to control the auto tranny.

Q) I was wondering what exactly has to be modified for this motor to work in my 03 350z ?

If you are referring to what modifications you need to do on the harness of the Aristo 2jzgte for the 2jzgte motor to work on your 350z , you will need the body plugs of your 350z. If you look at the engine harness of your 350z , all those plugs connected to your engine aside from the plugs that connect directly to your 350z ECU are the body plugs.

Q) I am trying to teach myself how to read diagrams so I can do this harness to save $1000 .. do I really need to learn how to read diagrams ?

Knowing how to read wiring diagrams helps a lot. But if you probably observed , I have been explaining every step into this harness build even the obvious because I am trying to do it in such a way that even those without strong electrical / electronics background would be helped.

Q) Since we know that our base harness is a 2jzgte Aristo harness and was working with the engine swap we bought , why don't we just replace all those broken plugs , be done with the 2jzgte part of the harness and all we have to work on are connecting the body plugs ?

That is a pretty good question. That will save us a lot of work if we don't have to do what we are doing right now.

Here is my point of view. IF you just change all the broken plugs , without checking every pin of each connector then you are making an assumption that every wire and unbroken plug that you got was good. What we are doing is not only cleaning up the wiring , replacing broken plugs and extending what needs to be extended , WE ARE ALSO already checking the actual harness itself from every point . It will be very hard to trace and work on broken wires / connectors once that harness is on the engine bay and installed. Much more, if you are building a harness for someone ... you don't want to get a call and let you know that something is wrong.

Q) Which of those wires in the Aristo 2jzgte harness needs to be extended ?

The Aristo 2jzgte harness being used in a right hand driven car is short if used in a left hand driven car. So it needs to be extended. So every wire of every plug that you will keep will have to be extended. For some , like if you are going single you will not need the VSV plugs . These VSV plugs have a wire that goes to the ECU 80 pin connector and since you are taking out those plugs if you are going single , then you don't need to extend them ....just take the wires / pins out. If you follow my 2jzgte harness build thread from the start , I did and will mention if a wire needs to be extended since we will cover every pin and wire in that harness.

Q) How long should the extensions be ?

If you are so **** about having the exact length , what you need to do is get your original harness and your Aristo 2jzgte harness . Compare them and see what is the difference. Like an SC300 harness will have components at the same location on the engine bay . Use that as your reference point for both and see how much longer is the SC300 harness.

Otherwise , for me 16" - 22" will be a safe number . 22" maybe quite long for some. In fact I got away with a friend's harness just by extending it by 12" . There is no set length here since not all let's say SC300 harness are same as I have shown you in a previous picture. But you don't want your extension to be short otherwise your plugs like the ECU 80 pin connector will be behind the blower box and it will be tough to connect your ECU.

It is better to err on the long side of extensions since it won't hurt anyway than being short. And make sure all your extension wires are all of the same length .

Q) What gauge of wire do you use for extension ?

Hard to tell you just one gauge number for a wire since not all the wires you are extending have the same gauge or are all same. Some will have a bigger gauge , some smaller and some are even different kind of wires like being a shielded wire. Rule of thumb will be , use the same gauge or one step bigger as that which you are extending for safety purposes meaning so the wire can carry the same current that the cuircuit was designed for. Using a smaller gauge than what you are replacing runs the risk of overheating that wire and even probably causing fire. I will prefer to use the same gauge so that harness won't bulge so much.

Q) Wouldn't it be good to use the same color code of wiring for the particular wire you are replacing ?

For those who rely on wire colors to trace wires , that would be ideal but might be tough to do . There are lots of wires with different colors and that means you will be buying a lot of wires from a hardware store if you don't have an extra harness to use. You are even lucky if you find all those wires with the same color codes as used.

Tip : Learn how to use a multi-tester checking continuity in a wire. You will find a wire easily .

Q) Looks like this thread will help a lot of people be able to make their own 2jzgte harness for the SC and save a lot of money. But would you mind if the knowledge they acquire from this thread will be used to make money meaning people making a harness for others for a fee ?

Not at all . Be my guest . One thing though , a disclaimer , as I have always said ...I am not taking responsibility of anything if someone decides to use whatever is written on this thread. Through the insistence of friends , I am just sharing how I did the harness I used in one of my 2jzgte swapped car.

For everyone who comes accross this harness build thread , I am trying to be as accurate as I can be in what I write here but at times I do a cut and paste to avoid retyping stuff and forget to modify some info . If you notice something that seems not right , please call my attention so I can edit the mistakes if ever.

The approach I did in making the harness is good not only for those with a Lexus SC . A 2jzgte harness will be the same for all cars that wants to use the 2jzgte engine. They will differ only on the body plugs and if a car has a particular or distinct setup.

Q) Is the chart that you keep on updating really necessary ?

Not at all ! For those who have made a couple of 2jzgte harnesses already, am sure they won't need it since they know which wire goes from one pin to the other. I suggested it here cause I know many will be newbies in making a 2jzgte harness. It is a chart to have a visual of what pins of what plugs you have finished working on and still needs to be done.

And later on once fully done .. if you want to do a quality control by checking again continuity from pin to pin of each plug , you can use it as a quick guide . It shows you were each wire goes.

Believe you me , if you are a newbie in making a 2jzgte harness you will thank me later on. I already got two complements from people who have done a harness and said they should have thought of that chart when they did the harness and would have made things easier.

Q)Ok now since you know that I will be tackling this for a 350z, your saying that I need the main body harness connected off of a 2jzge equipped car, auto or manual ? Also is it not possible to just wire up the 350z body plug to the 2jzgte aristo harness instead ? The 350z uses can bus communication , will that effect anything ? And also still trying to fig out what diagram you need lol.

I believe, you might not be understanding my email answers to your questions..

Let's do this , to make it simple for you...which body plugs of the 350z you need ?

You see this 350z engine lets say that came out of your car. There you see the 350z engine harness wrapped around. Some of those plugs in that harness will be the body plugs and you will need them .



In addition , since you don't have the 40 pin ECU connector in a 2jzgte aristo harness , you will need to secure that . That is the reason I suggested getting a 2jzge engine harness from the junkyard so its cheaper and you can use the wires for extensions.

Is it possible to wire the 350z body plug to the 2jzgte aristo harness? That is exactly what you will do later that is why you need the 350z body plugs.

No offense meant , I suggest you familiarize yourself with your 350z wiring so you know exactly which connectors you will need to use with the Aristo harness as I have never done a 2jzgte swap on a 350z. I will give you a hint . On one side of that 350z engine harness is where you connect the 350z ecu. Any connector whose pin do not terminate into the 350z ecu but instead into another plug , you will most likely need.

gerrb

iTrader: (34)

Q) What if I am using an AEM v2 or AEM Infinity or Haltech or a ProEFI ecu , is the wiring the same ?

IF you are using the AEM v2 ecu that was meant specifically for a 2jzgte engine , then you have nothing to do with your finished 2jzgte harness . They are plug and play meaning , AEM designed the ecu around the stock 2jzgte pin configuration.

For ProEFI , no . They sell a patch harness that connects to your finished 2jzgte harness and to their ECU. If you want to directly wire your 2jzgte harness into the proEFI ECU , then you have to use their ECU connectors at the end of your 2jzgte harness wiring. IT is not hard to do. All you need is the pin configuration of the proEFI ECU which they provide and your connectorss / pins . It's the same process we have been doing. You just have to know which pin should go to what pin. Well, incidentally Richard , 8052jz had just asked me that very question yesterday... a 2jzgte harness with proEFI.

Same thing with Haltech, they have a patch harness.

Personally , this is what I will do . Just my personal opinion and am sure some won't agree with me. Hey , who am I to argue with the Pros after all ? Am just a diy dude like most people on this forum. What I did on one of my SC with proEFI was create my own patch harness that goes between my ProEFI and my stock 2jzgte harness so I save .I didn't have to buy the more than $500 patch harness that was sold on top of the proEFI ECU. I didn't feel like hard wiring the proEFI connectors into the end of my 2jzgte harness also . WHY you might ask.

This is my rationale :

a) What if one day my proEFI ecu konks out so I need to send it out for repair but I badly want to use my car and I know I have a tune on my Haltech or AEM ecu for the same car ... then I can't use those ecu because I have hard wired my 2jzgte harness with proEFI .

b) Or one day , I simply decided to use another ECU , maybe a new and better ECU that is now available. We all know something always comes out on this electronics gadgets. Before the proEFI hit the market , AEM received all praises , then something came out ... the proEFI .... and the AEM ecu became inferior to some ...now even a lot of tuners will swear by the proEFI being a lot better than the AEM . What if something else comes out better . Then I have to get my 2jzgte harness that is hard wired to proEFI modified ? (Didn't you just spend tons of money getting those proEFI connectors in there that is if you previously had the stock connectors ?) Wouldn't that be another big expense ? Harness Modifications can costs tons of money.

c) Or let's say for whatever reason you need to part out your car. We all said the same thing , no way I will let go / sell or even part out my car. But how many high horsepower cars we have seen parted out ? Come to think of it they have more reasons not to let go or part out the car. But things happen . You do what you got to do. Let's say you are parting it out and selling your parts. You will have less audience buying that harness I will assure you cause there would be not so many having an SC with proEFI.

These are some of the reasons why for me , I prefer not to hard wire the 2jzgte harness to a particular ECU. I will rather make my own patch harness if I don't want to spend that much buying the patch harnesses of some ECUs that is if it is cheaper to make one.


Q) So basically all wires are getting extended closer to the ecu connector and not near the actual connectors ?

Yes sir ! Remember , the connectors on the 2jzgte harness are already laid out correctly based on where the engine components are. One reason I used the 2jzgte Aristo harness as my base . All the connectors for the actual engine you are using are already there correctly laid out for you. You are doing the extending just because you want the ECU connectors and body plugs to get into the passenger footwell... remember it is short just because Japanese cars are right hand driven.

Q)Is there anything in particular that is different when extending shielded wires?

Not really. Just be mindful of the size / gauge .

Q) Amazing information so far. very easy to follow. thank you so much. makes me want to build a custom harness myself now as a back up or for fun . Also where can these shielded wires be purchased? and what gauge are they?

Thank you buddy !

Wires can be bought at Radio Shack. This I suggest , in my opinion , it will be cheaper to buy a 2jzge / 1uzfe harness from the junkyard. Choose a good harness with good connectors. You will have extra connectors if you happened to buy a harness in good shape. You have the wires you need for extension both shielded and un-shielded . And since they are Lexus / Toyota harness , the wire gauges will be almost same.

Shielded wire gauges are not all of the same sizes. Some shielded wires have only one wire at the middle . Some will have two and so on .. so beware of that.

So for me .. junkyard is a good place . And you know how expensive things can be on these hardware stores at times. If you get a good harness from junkyard then you can have extra connectors you can use to replace broken connectors.

Q) If connectors with their pins are expensive and I have a lot to replace , why don't I just buy a new harness then for $1000 or get a good one from the forums ?

Knowing how to make a harness doesn't necessarily mean you should make a harness when you need one . If you can get one for a very good price and suits your purpose , then by all means buy one.

One reason why you want to learn how to make one is , if you have a special setup with a lot of non stock components or parts . Then you can be very flexible in you harness when you know how to do it. Buying one ,you are stucked with how it had already been done. But if you know how to do it , you can modify what you bought to suit your needs and don't have to spend asking someone to modify it for you.

Q) How is that Radio Shock Part # 275-233 0.5 Reed Relay wired ? I already have my car running but the shop who did the swap was never able to get my AC running . Can you please help me on this now or do I have to wait till the end of this harness build thread for the explanation ?

Since some friends and a number of other people had inquired about this , let me get this cat out of the bag now ...

If you haven't read the last Question and Answer POST , please do so. I have mentioned there why many Aristo 2jzgte swap do not have a working AC. I wouldn't explain it again here.

What I will explain here is how to wire that Radio Shock Part #275-233 0.5 Reed Relay

Assuming that you have a good 2jzgte harness for your Aristo 2jzgte swap , Observe Figure A . You have the 40 pin ECU connector ... you got there PIN 34 and its wiring as it sits now.

On Figure A ... connect those two wires from the relay , the one from top and the one on the right (there are two relay prongs just below that top relay prong) to pin 32 of the 40 pin ECU Connector. That pin 32 supplies +12 volts .

NOTE : Some SC300 / SC400 / MKIV harness has pin 32 of the 40 pin ECU connector empty meaning there is no pin or wire on the slot. Then use pin 31 of the 40 pin ECU Connector .

Then CUT THAT WIRE from pin 34 of the 40 pin ECU Connector and connect those two wires to the Reed Relay as shown on Figure B.





And go for a ride on a warmer day and let me know if your AC is working , assuming that AC system has no other mechanical problems .. ENJOY your cold AC while I will enjoy my cold Patron Margarita !

NOTE : This solution is for those using an ARISTO 2jzgte ECU.


Q) So , if I get you right , I will need to insert a relay on the Switch On button of the Lexus HVAC control to turn on a relay and in turn the relay turns on the AC by giving the ECU the positive signal needed . Now if I let's say take out the HVAC control which wire is for that switch on button ?

What you said is right . The act of inserting a relay on that circuit actually allows you to reverse the signal polarity sent to the ECU on pin 34 so it can enable another circuit which is on pin 23 that actives a coil and then allows power to flow through the AC magnetic clutch. Again the ARISTO ECU needed a positive 12v signal but the Lexus HVAC control was providing a negative signal.

BUT LISTEN TO THIS .... You do not have to take out that HVAC control unit and start looking for the wire from the switch button.

If you read again what I said in the previous Q&A where I drew the circuitry of the Reed Relay , I said . ASSUMING THAT YOU HAVE A GOOD 2JZGTE HARNESS FOR YOUR ARISTO 2JZGTE SWAP. If you indeed have one , then it should have already the correct wirings you need that goes to the correct plugs.

All you need to do is pick up that 40 pin ECU connector and get the wire from pin 34 . If you have followed this harness build from the start , by now you should know which is PIN 34 by looking at that 40 pin ECU connector. You may cut it wherever you want . On my end so as not to have so many cuts on the wire , I cut it again in one of my extended points (Remember you extended that wire ? )

Q) My harness was done by a "pro" but I am using a jdm supra six speed ecu instead of an ARISTO ecu. I already had the harness made with the needed relay wired in the a/c circuit but it still never worked. Is it because I am using the wrong ECU ? . Is that hyper sensitive relay really needed with the jdm or usdm SUPRA MKIV ECU? Also I was told by the "pro" to cut the relay out and cap off the wires on the 12v feed and connect the other to each other. But now I'm going pro efi and need to figure out hot to get that going so I'll wait for that part I guess.

Sorry to hear that buddy . I hope I am understanding what you are saying ... that is , you bought an harness with that hypersensitive relay already incorporated and still your AC doesn't work . At the same time , you took the relay out just to bring the wiring back to original state before the relay was added and still your AC won't work .

Hmmm .. I have a good solution for you ! Give me that freaking SC300 and I can live without an Air Condition and you won't have any problem with it anymore.... . Everyone on this forum is dying to have the kind of car you have no doubt.

Kidding aside , let's go through your questions ..

a) Am I using the wrong ECU ? Well , your car runs well .. so yes and no . NO for everything since your car runs well and YES for the AC since the AC do not work. The solution I mentioned above was for the Aristo 2jzgte ECU. BUT let us investigate this further with regards your ECU.

b) Is that hyper sensitive relay really needed for the JDM or USDM MKIV ECU ? Based on what you have said , when it was connected , you had no AC . When you took it out , you still have no AC. So based on what you said , probably not . Not sure for now so we have to investigate further your case.

c) You think if I use a USDM MKIV ECU , assuming I have the right injectors / resistor pack and wiring will my AC work with that relay ? No it will not and I will tell you why I believe it will not.

The JDM and USDM MKIV cars basically has a lot of similarities in their wiring diagrams and circuitries. I have just look at their Air Conditioning Wiring Diagrams and basically are the same so since you are currently using a JDM MKIV ecu and AC didn't work with that relay , I honestly doubt it will work even with a USDM MKIV ecu. Again, needs further investigation.



These are my initial thoughts on why you have no A/C whether with or without that relay. I will further investigate though I would like you to do something for me to confirm that the other parts of your A/C system is good.

Maybe :

a) You got a bad connector / wirings for Pin 23 and Pin 34 of the 40 pin Connector or mechanical problems in nature like bad pressure switch, shorted or open clutch wiring , stucked up or bad comppressor or not enough freon.

b) Maybe the relay which is activated when pin 23 is grounded by the ECU is bad . That relay provides the actual path for electricity to flow towards your A/C magnetic clutch.

c) On the JDM and USDM MKIV ECU , pin 34 of the 40 pin Connetor , which is the A/C request signal , based on the diagrams goes through another computer before it goes to the main Computer . So maybe , there is another process going on in their circuitries before the circuit on Pin 23 of the 40 pin Connector is grounded by the ECU which in turn should provide power to a coil for a relay switch which allows current to flow to the A/C magnetic clutch thus turning on the compressor.


This is why I want you to do this for me please . Get an SPST (single pole single throw) Toggle switch. Connect one port to the ground . Disconnect Pin 23 from the 40 pin ECU Connector. Connect the other port of the toggle switch to that Pin 23 which you just disconnected from the 40 pin ECU connector. Start your car , turn on that toggle switch and let me know if your AC is working. If it does, you know there is nothing wrong in your A/C system and that relay which allows current to flow to the magnetic clutch . IF it doesn't and that relay along pin 23 which when energized allow current to flow to the magnetic clutch is not bad , then your problem is not on the wiring . Another way , if you don't have a toggle switch , when you have taken out that pin 23 from the 40 pin Connector , while your car is running connect that pin to ground and if there is nothing wrong mechanically with your A/C system , you should hear that compressor kick in and have cold air.

Let's do that , start from that side of the A/C system and move or probe backwards , so we can determine what is the real problem why you have no A/C. We will nail down the culprit . Finding what the real problem is easy. In fact if that Toggle Switch will get your AC running then you have a primitive way of turning the AC on right now.. hehehe..It ain't optimal but you know your AC is working. I said it is not optimal because everytime an AC request is done, the corresponding engine speeds are supposed to be manipulated by the ECU so your engine wont die specially when you are idling.

Q) Will I need this relay with the pro efi for the a/c or no ?

That HYPER SENSITIVE RELAY , no you don't . Most aftermarket ECUs have available wirings / pins used for switching components. Some will just provide ground to a circuit and some can provide the (+) positive voltage signal.

How come these aftermarket ECUs have those and our 2jzgte ECUs don't you might ask ?

Remember these aftermarket ECUs were manufactured to enhance or be able to squeeze more power out of the 2jzgte power plant but of course with the corresponding engine upgrades. And many of the original pins / wirings of the original or stock 2jzgte ECU are not anymore used (remember us on our harness taking out those VSVs and anything not necessary but occupied pins from the original stock ECU connectors) so some of these they use for Low Side switching (meaning just grounding the circuit) and for High Side switching (meaning providing + signal for some cuircuits that needed it ).

Q) Wouldn't it be better to wrap those corrugated flexible hose wrap also with electrical tape ?

Yes you can . It is personal preference and true , wrapping that corrugated flexible hose with electrical tape will also provide extra protection on your harness.

At this point , there will still be wires added during the merging process. You don't want to finalize your wrapping then undo due to the fact you need to add wires.

On my end , I don't wrap all corrugated flexible hose with electrical tape. It depends which one. When you wrap the whole corrugated flexible hose with electrical tape , it becomes kinda stiff ... looses flexibility. That's one reason I wrapped the wires of each plug before I wrap them with the corrugated flexible hose.

Q) So how long does it take to make one 2jzgte harness assuming you have all the materials like plug , electrical tape, flex hose ..etc ? Cause I got one done and I was told 6 -8 weeks and if I pay the extra amount they charge , it will be facilitated in 2 weeks ? It surely be nice to say that I did my own harness even if I am not an automotive mechanic or electrician .

Look , I don't want to be in trouble here with those who do the harness for a living . Every person or company has his own way of doing things . They have their own protocols on how they do things. So it will depend on each individual , company , skill sets of employees , how much workload they have .. and so on. So there is no cut and dry time frame ..it all depends on the company and individual .

You yourself should be able to make your own estimate based on your skills set . Now that you have all the pin configurations all laid out to you , you don't have to go through diagrams tracing circuits ..maybe at the end for quality control you can. How long does it take you to cut and make a good solder ? How long does it take you to do the other stuff like shrink wrap , how long does it take to check connectivity and for how many wires / pins are these..... and so on.

My personal opinion , if one is good on all of these , all materials available at hand and with all the pin configurations laid out in front of me , I personally don't see any reason why I cannot do a 2jzgte harness in two full days . For the experts , maybe a day .. I said maybe. The most laborious part I told you before was the cutting and soldering .. I hate that to be honest with you. Then quality control ...I won't fully wrap a harness till I know I have gone through every pin of every plug again checking their connectivity , that's another day for me. The secret for me is having the right tools . It facilitates and makes your work a lot easier .

So it all depends on the person doing the work .

gerrb

iTrader: (34)

CONCLUSION

Though there are still posts I need to edit , I am writing my conclusion here so people who wanted to comment or ask questions can now do so. As I have mentioned, this may not be the best way of doing a 2jzgte harness for our beloved SCs or MKIVs but I was always successful using this approach. If you learned the process, which was the real objective of this write-up that is showing you a way to do it (it's not the only way), you don't have to copy the information verbatim while doing the harness. You yourself should be able to extract and verify what we have written here. Truly what you need now are the Wiring Diagrams which we have posted. I just do hope that if someone decides to work on his own 2jzgte harness , he will be successful. If you have questions, feel free to ask them and I know a lot of good people here will answer you.

Hoping that this thread will help a lot of people or DIY guys make that special harness for themselves. As I have always said , there is nothing special when a professional heart surgeon saves someone's life just because that is what is expected from him but when an non medical person is able to save someone's life it is something everyone talks about and for which he can be proud of for the rest of his life.

I maybe happy having 6 speed MKIVs built by well known Supra Builders but it wouldn't top the happiness I have when I drive the car that I personally built from the ground up just because I am not a mechanic and never wrenched before. Someone always worked on my vehicles. It took me a while building my Red Mamba 1 since I learn as I go , spending countless hours on that harness since it was my very first but at the end I know it always brings a smile on my face just knowing that I did it myself.

My very first 2jzgte harness allows this 650rwhp + 150 Nitrous shots 2jzgte swap with Auto Transmission to run ! If I can do it , I know you guys can do it .

gerrb

iTrader: (34)

Thanks .. hopefully it will help those doing a 2jzgte swap.

CatManD3W

iTrader: (18)

Thank you Gerrb....This is going to be a great help for me....you may see some PM's from me come your way in the future...

gerrb

iTrader: (34)

You are welcome... you can PM me anytime. If you think your question will help others , I suggest you post it here . There a lot of good people here willing to help.

jwin

iTrader: (16)

Great Great writeup. Maybe I should swap my motor for a 2jzgte. Lol. Hopefully I can make a DIY to hardwire the sc300 harness to the proefi. Wish I had a 2jzgte since it might be more helpful for members wanting to save the 700 bucks for the adapter harness.

gerrb

iTrader: (34)

Thanks JWIN. Go ahead buddy and do a DIY so others can be helped. There might be some who might want to do same thing as yours. Those firewall plugs you are working on will make a clean install.

PaCowboy

iTrader: (6)

Holy crap. That is the most detailed write up I've ever seen. This is amazing info. I have to start on my harness this week. Gonna be a pro or a complete failure by the time it's done.
Thans for taking the time to write up something like this. I know there are gonna be a lot of guys in the community appreciating this. I know I do