EJ20 in GC *Good Wiring Help* - Subaru Impreza GC8 & RS Forum & Community: RS25.com
 
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EJ20 in GC *Good Wiring Help*
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Old 01-24-2007, 04:46 PM   #1
theNinja
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Arrow EJ20 in GC *Good Wiring Help*

Ok, so I can't post links yet because I'm too "new" but you'll get the idea when the time comes.

For the past year I've had my 2000 2.5RS I've done nothing but put regular maintenance stuff into it trying to get it running right and to clear this check engine light from hell (O2 sensors front and rear, PCV valve, grounding kit, new battery, new tie-downs, new battery terminals, fuel filter, spark plugs, plug wires, etc). Might not seem like a lot, but when this driveability problem pops up every month and then tricks me by SEEMINGLY going away with every bit of maintenance I do, I've finally had it. I can't spend any more money on maintenance and time worrying about whether my car is going to break down on me. So I took the time to ask everyone that seemed intelligent every question I could and I searched the internet high and low for whatever information that I could. The best help that I can come up with so far are THESE SITES:

The * is a . in the following links. If you think I'm a newbie and trying to post hazardous links then just don't type them into your browser. The only way I feel I can contribute to a community and raise rank is to help. These sites HELP.

ECU Pinout diagrams for basically any Subaru that you need to swap to/from:
northursalia*com/modifications/misc/wiring/wiring.html

Pinout Matrix created by Sam Barros when doing a JDM Ej20 swap into GC:
powerlabs*org/wiring.doc
His whole writeup:
powerlabs*org/jdmsubaru.htm

Sport Compact Car's GENERAL writeup on a USDM Ej20 swap into GC
sportcompactcarweb*com/tech/0403scc_subaru_gbd_wrx_engine/photo_01.html

All of this information is very helpful as a whole and to be honest will be all I use to start this swap if I have to. Does anyone have anything better? Not to sound like an idiot here but does anyone have a write-up that breaks this swap down to the level of, "Step 43: connect blue wire 23 from RS harness to white wire 10 on WRX ECU, Step 44: connect green wire 24 from RS harness to yellow wire 15 on WRX ECU", etc. I know people have to make a living and I know this is some hush-hush swap info that nobody wants to give out, but come on. (seriously) Screw that. I know there are regular people out there with the capacity to convey this information to other enthusiasts simply and efficiently via the internet. The everyday Joe that wants to do this swap is not considering doing it for a living and stealing business from the big companies out there that are apparently worried about this.

And so, I’m done. I hope the sites above help someone else as much as they appear as though they’ll help me. I dunno if they’re even that well-known but it took me quite a while to find them myself. And if anyone lives in my area (Virginia Beach, VA) and has done this swap and wants to help out or drop me an email of tips or ANYTHING please do so.

Last edited by James555; 09-18-2017 at 01:59 AM..
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Old 01-24-2007, 05:51 PM   #2
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Subscribed, doing mine in 2 months, gonna need some good help, unfortunatly you're to new to be able to post links. I'll figure it out though. haha
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Old 01-25-2007, 11:18 AM   #3
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Ok, so who lives near Virginia Beach, VA (23454) and wants to come help with a USDM WRX swap into a GC chassis?

On top of this... someone clear this up for me:

What does the WRX ECU control that isn't related to the motor?
and
Where does all the merging/cutting happen? If the motor is WRX and the ECU is WRX... where's all the cutting and merging coming from?
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Old 01-25-2007, 11:26 AM   #4
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Ok, basically it will work like this

You take an RS, pull out the motor, dash, ECU and all the wiring harness that is in the dash/motor. Then you take another motor, drop that bitch in. You take the wiring harness that came with the motor, plug everything into the motor that you can, anything that will lead directly to the ECU. Any plug that goes directly from the motor to the ECU will not need to be merged.

Then, after all that is plugged in, you find out what stuff you still need to wire up for the dash. This includes the dash, cruise control, climate control (heat, AC), etc. These are what need to be merged since the wires that run them are in a different setup than how the JDM plug accepts them. You lead the JDM wire to where it would go into the old car. If it was a speed sensor you lead it to where the speed sensor is in the dash.

You then plug in the stock RS harness to that part. You lead the wire you want to merge where you want to plug it in and then cut both wires leaving some slack between them. You then solder the two wires together. This will then simulate the correct wiring.

This is my understanding of the process. If there is anything wrong with my explanation, someone say something. Also, it doesn't have to be wired in the car, you can wire everything up outside the car no problem. Just put everything on the floor and start wiring shit up.
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Old 01-25-2007, 04:35 PM   #5
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Quote:
Originally Posted by Renegade_
Ok, basically it will work like this

You take an RS, pull out the motor, dash, ECU and all the wiring harness that is in the dash/motor.
What wires in the dash? Are you referring to the wires coming through the firewall from the motor or are you talking about interior lights and radio wires etc? If you're referring to the radio wires and the dash lights etc, why would I have to pull these wires? The ECU and motor connections shouldn't have anything to do with these... right?

Quote:
Originally Posted by Renegade_
Then, after all that is plugged in, you find out what stuff you still need to wire up for the dash. This includes the dash, cruise control, climate control (heat, AC), etc.
Cruise control, okay. I can see that (I guess), but climate control etc? Why does all of this need to be merged with a harness for a new ECU? From what I've read/been taught there is no connection from the ECU to the climate control switches, dash lights, etc. If I have NO ECU in the car whatsoever, these features should still be able to work provided I have a battery connected and the factory switches. Or am I wrong? Hell, studying the pin-outs for every ECU I've ever read, there have never been wires leading to climate control switches etc.


EDIT: Okay after looking at the RS pinout again I do see ECU connectors for the A/C switch. That's it. Everything else is motor related... nothing else...

Last edited by theNinja; 01-25-2007 at 04:38 PM..
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Old 01-26-2007, 06:53 AM   #6
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Ok, so in my quest for knowledge of course I've consulted another subaru specific message board for help as well. Because I want people's input here on what was said there, and for the fact that I'm not going to (nor can I because I'm too new) hyperlink the two, here is what was being said. Anyone's comments would be appreciated:

Quote:
Originally Posted by SomeGuy
The ECU needs to be wired to and from things like the ignition relay, fuel pump relay, trans., tach., all the idiot lights, test and fault code plugs, radiator fan control, all the ground points for sensors and 12v through the ECU - ect....
Ignition. relay - under the hood
Fuel pump relay - under the hood
Transmission relays - under the hood
Tach is not controlled by the ECU
Idiot lights - ONE, the check engine light
Test and fault - under the hood
Radiator fan control - not sure where it is but probably not behind the instrument cluster
Ground points for sensors??? Behind the instrument cluster???

Quote:
Originally Posted by SomeGuy
Or you can just cut off all the ECU wires and crimp them to your turbo ecu then run wires for all the turbo specific sensors last.
Well, I dunno about using crappy ol' Auto Zone crimps to do the trick but the more I read about this swap the more I think this is the SMARTEST way for DIY swappers. Really, sitting here still (day three) looking back and forth over these pinout sheets... there are very FEW electrical wires going from the ECU into the dashboard. I'd much rather just "crimp" these 5-10 wires to the new ECU. And voila, there is no need to remove the whole dashboard...

Someone please tell me if there are any pitfalls to this.

For example:
Check engine light

Out of RS ECU it says
"Light ON - 1 or less // Light OFF - 10-14"
Out of WRX ECU it says
"Light ON - 1 or less // Light OFF - 10-14"

This says to me, I don't need to run a whole new wire/plug up to the check engine light. Make sure the RS engine light wire stays there around the ECU area so I can connect the WRX ECU to it. There, that just saved me 3 hours of pulling off a dashboard (not really but you get the point). The more I read, blower motor switch, rear defog switch, small light switch... they all show the same values. Why run all new wires to these places when the factory wiring behind the dash will do the trick?

Quote:
Originally Posted by SomeGuy
Do your swap and make a step-by-step how to for everyone else to use
Maybe you were being sarcastic, but honestly, I will try. A couple buddies of mine got GCs a year or so after me and they are definately trying to do swaps to them. If not for posting online (which I would), I will at least make one for MYSELF so I can do it again on their cars.
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Old 01-26-2007, 07:07 AM   #7
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you will need to merge everything non engine related into the RS. ie: every plug from the engine that goes to the ecu is untouched. BUT there are a few wires that will need to be soldered in from the engine harness.

What we do is separate the engine controls from the WRX harness. Basically that gives us a separate "donor" harness. You will have quite a few wires that have no plug attached.
Once that is done, we run that into the firewall. From there depending on the year of the swap car, we splice those left over wires to their new homes in the RS harness.
Some shops actually pull the RS harness as well and merge the WRX and RS harness together outside the car. We don't. Everything is done inside the car.


I will not get into details as to which wire goes where, and what needs to be cut so forth and so on.
Every car is different so to give a detailed how to would be impossible. Not only that it would take way too much time to say give you a how to on a certain year. PLUS WRX harnesses have changed through out the years.... so no. no instructions

One major problem I have with "tire kickers" is when they ask how much a swap is.. I give them a price which usually is around $5500 on average, they always say.. "why so much?" Untill you see what is involved with the wiring, you may never know.

Good luck
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Old 01-26-2007, 07:10 AM   #8
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ssubscribed....i always wondered this too. i will be doing my swap in the begginning of the summer...
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Old 01-26-2007, 09:12 AM   #9
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Quote:
Originally Posted by Area1320
Everything is done inside the car.
That is the most inspiring bit of information I've gotten to date. I knew it was possible. I knew it! I also think I know how to do this pretty (uh oh I'm gonna say it)... easily.

Saying is one thing. Doing is another. I'm so ready to try this. Time to get my finances straight. Thank you for the info.
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Old 01-26-2007, 09:51 AM   #10
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no prob. Best advice I can give you is get the wiring diagrams for both cars. Learn where every connector goes and its function. And learn how to read them!!!
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