JDM and USDM Wiring incompatibilities.

[Auladan]

Okay... I hope I can word this coherently.

So! I own a 90 TSi AWD, and I melted the motor (timing). Now, I ordered a 1G JDM motor from, obviously, Japan. I have it bolted into the bay, and today I tackled the electrical.

And today I ran into some problems, as I figured I would. I had to take out the wiring harness from the JDM longblock in place of my old one, becuase it was cut. I got my old wiring harness situated just right, and started to fit everything together when I noticed several differences in the two wiring harnesses. The JDM one had a plug that mine didn't, and it plugged into this small box on the side of the throttle body. My old harness wouldn't fit where it was supposed to with that box in the way, so I was forced to swap Throttle bodies.

Out with the new, in with the old. So! Everything was peachy after that. I got some vacuum lines put into the Throttle body, and I did all of the injectors, then I notice another incompatibility. The spark plug coils on this JDM motor are located in a different, though admittedly better area. But, the electrical plug to them is different, and doesn't match with my old harness. The same plugs (the ones from both harnesses that do the same job) are different. The JDM one is more triangular, and only has three wires fed into it. On my harness, that same plug is more squarish, and has four wires fed in to it.

Now I'm stuck. I don't know what to do...

Then I find ANOTHER incompatibility. On the backside of the Intake Manifold is this small power fitting (for lack of a better word) where this rather large plug off the JDM harness fits in to. Well, the same plug on my old harness, that does the same job, is of a slightly different configuration, and won't fit. I can't find my old 'power fitting'.

Two problems I can't seem to fix. Ugh. Everything else matches up. Those are really the only incompatibilitie's that I could find.

So, after apologies for the long post and thanks for reading it, what do I do? Do I need to buy a 1G JDM wiring harness, or is the difference in harnessess only year-based? I don't know the year of the JDM motor.

Any help would be VERY MUCH appreciated. If needed, I can get pictures up soon.

Thanks again.

 

[Auladan]

Anyone know? I'm looking for similar wiring harnesses (similar to the JDM) online, but so far no luck.

I'm hoping I can just rewire a few things and be done with it; I've waited a year and a month to get this car running. I've run out of patience.

 

[NOSNUSE]

As far as your coil pack why don't you put the original intake back on, that way you know the the coil will be in the right spot and the plugs will fit. Just my .02 though.

 

[Auladan]

That's a bloody good idea.

I worked at a friends place (because I don't have a job, and no car to get one), putting up siding and moving furniture, to earn enough for a Haynes Repair Manual on all 1990-1994 DSMs. After looking through that I found that 1990 was slightly different in its wiring than all 1991-1994. I thought I'd need a whole new wiring harness.

I'll go with your idea though; thanks a million. Sometimes the answer's right under a tarp beside the woodshed.

 

[Auladan]

Just went out and looked everything over, and figured something out. I don't need to swap manifolds at all.

I already swapped Throttle Bodies, so that's good and done. Now all I have to do is swap the spark plug coils and the little power box deal (I still don't know what to call it), and fabricate housings for them since they don't bolt up to my 91+ Intake Mannie. Everything else lines up just fine.

By monday I should be driving. I'm freakin' elated.

But, one of the coils is bad on my 90', so I might need to buy a used one. Anyone have a ballpark for how much I should expect? I know a new one could run a couple hundred, or so I've heard. I don't have that kind of money.

 

[NOSNUSE]

Here is one place: http://www.diamondstarmotorsport.com/elecparts.shtml

I think I have one here I can sell to you for real cheap, it worked when I took it off to rebuild the engine, and I forgot I had it and bought a new one .PM me if you are interested, later.

 

[Nighthawk01]

use the jdm longblock and bolt all you us dsm stuff on from your old engine and be done with it.....

 

[Auladan]

I've lost my mind.

Spent the day, with me pappy, modifieing the JDM coil pack (mostly the bracket) to fit on to the engine and work with my 90' wiring. So, all seemed good, when I found out my vacuum setup is completely different.

Their's a Triangular shaped bracked uner the Intake Manifold that on my 90' has four hard hoses, where rubber vacuum hoses plugged in to from both sides. The JDM bracket only has three hard hoses. Plus, their are four vacuum hose-nipples on my 90' throttle body, where on the JDM their aren't any, and the vacuum nipples are instead somewhere on the intake mannie. Grwar.

Hopefully tomarrow when it's sunny out I'll be able to make heads or tails of it.

 

[Nighthawk01]

Originally posted by Auladan
I've lost my mind.

Spent the day, with me pappy, modifieing the JDM coil pack (mostly the bracket) to fit on to the engine and work with my 90' wiring. So, all seemed good, when I found out my vacuum setup is completely different.

Their's a Triangular shaped bracked uner the Intake Manifold that on my 90' has four hard hoses, where rubber vacuum hoses plugged in to from both sides. The JDM bracket only has three hard hoses. Plus, their are four vacuum hose-nipples on my 90' throttle body, where on the JDM their aren't any, and the vacuum nipples are instead somewhere on the intake mannie. Grwar.

Hopefully tomarrow when it's sunny out I'll be able to make heads or tails of it.

It would be so much more simple, if you just used the jdm longblock.

bolted all your stock stuff up to it,, your entire intake manifold, and everything with electronic connections on it. would save alot of time and agervation.

 

[Auladan]

This is my first motor swap, so I suppose many of the things hanging me up and frustrating me are things an experienced eye would have no problem working around/fixing/what have you.

Anyhow, thanks to another DSMtuners member and a 17 dollar Haynes repair manual I re-did my vacuum lines; I took apart all the emissions control stuff and hooked up the necessary lines. I live in Washington State, in a county where Emissions aren't an issue so I don't have to worry about that.

As it stands:

I've got the JDM longblock bolted in to all four motor mounts, and the only part I had to swap out was my '90 Throttle Body. I modified the JDM coil pack to work with my '90 wiring and got that back in. I lined up almost all of the electrical for tomarrow, and I'm praying my vacuum setup will work. After I modify the coil's power transistor and mount that on the back of the intake manifold, I think everything else will fit right together.

Wish me luck! I'll let everyone how it goes and possibly put up some pictures when I get her running.

 

[dsmracer69]

on the jdm coilpack you can use the bracket and coil packs just pop the cap off the back off the coil packs and switch the wiring from ur us coil pack its the same pack the wiring is different and it comes off i just did this a week ago

 

[Auladan]

Yep, that's exactly what I ended up doing. I had to extend a wire though, because where I fitted the small power transistor (I guess that's what it is), the wire wouldn't reach where it's meant too. Pretty simple once you understand what you have to do.

 

[dsmracer69]

Yup just have patients man its gonna make you real madd