pointers for wiring harness swap

ncarn8 · 05-05-2009, 01:57 AM

Hi guys
I have a JDM N/A legacy, ej20. I also have a V3 STI engine, gearbox. I purchased the Wiring loom (from the same body shape but turbo version) to go in. (All plugs the same apparently, like heater, etc)

Im a bit sketchy on jow difficult it will be to swap the entire loom, ie rip one out and put the other in. Is it that simple, or are there some big areas to watch out for? I have the diagrams, the loom and the car.
Just asking for any advice or tips from those that have fully dismembered their cars for a similar thing.
Thanks

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DHRDAN · 05-08-2009, 02:33 PM

I would try over on www.rs25.com forums for this question. There are a few people over there who have done a leggy swap.

As long as you have the entire wiring diagrams from both cars, it's mainly a matter of using the new ECU and adding in any accessories that you will need that DO NOT have the same plug/pinout.

ie. If the new ECU has a plug for the speedo, and its not the same as the plug on your old harness, you need to cut the new harness and wire in the old plug, or get a new cluster.

Scoobyslack1 · 05-08-2009, 06:19 PM

Is the new harness for the new motor? Will it replace the whole front harness?

Stretch out the harness on the floor & label everything you can find.
Go through and find everything you will need to splice.
Write out what wires go together. It will help keep it straight instead of trying to read the diagrams while splicing.
Also, if the is anything you don't need (AC, ABS, etc.), find those wires and remove them. That will help keep it cleaner.

ncarn8 · 05-10-2009, 07:27 AM

Quote:

Originally Posted by Scoobyslack1

Is the new harness for the new motor? Will it replace the whole front harness?

Stretch out the harness on the floor & label everything you can find.
Go through and find everything you will need to splice.
Write out what wires go together. It will help keep it straight instead of trying to read the diagrams while splicing.
Also, if the is anything you don't need (AC, ABS, etc.), find those wires and remove them. That will help keep it cleaner.

I have started with the labelling. It shouldnt be too hard. Good idea about removing the excess, there will be alot no doubt.
The loom is from the factory turbo version of the legacy body shell, so it should line up. The engine is later model but i have modded older sensors to it, so it should just work. (saying should alot

)
I guess if i label identify every plug, and play it slow and methodical it will be time consuming but not brain straining. I just hate wiring, its so easy to get confused.
Cheers

Scoobyslack1 · 05-10-2009, 11:19 AM

Quote:

Originally Posted by ncarn8

I just hate wiring, its so easy to get confused.
Cheers

That's why I wrote down all the splicing I had to do.
Most of the sensors should be the same, cam & such.

05-05-2009, 01:57 AM	#1
ncarn8 Scooby Specialist Member#: 71419 Join Date: Sep 2004	pointers for wiring harness swap Hi guys I have a JDM N/A legacy, ej20. I also have a V3 STI engine, gearbox. I purchased the Wiring loom (from the same body shape but turbo version) to go in. (All plugs the same apparently, like heater, etc) Im a bit sketchy on jow difficult it will be to swap the entire loom, ie rip one out and put the other in. Is it that simple, or are there some big areas to watch out for? I have the diagrams, the loom and the car. Just asking for any advice or tips from those that have fully dismembered their cars for a similar thing. Thanks * Registered users of the site do not see these ads.

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05-08-2009, 02:33 PM	#2
DHRDAN Scooby Specialist Member#: 204358 Join Date: Feb 2009 Chapter/Region: SCIC Location: Santa Paula, CA. Vehicle: 01 2.5RS W/ EJ257 Black	I would try over on www.rs25.com forums for this question. There are a few people over there who have done a leggy swap. As long as you have the entire wiring diagrams from both cars, it's mainly a matter of using the new ECU and adding in any accessories that you will need that DO NOT have the same plug/pinout. ie. If the new ECU has a plug for the speedo, and its not the same as the plug on your old harness, you need to cut the new harness and wire in the old plug, or get a new cluster.

05-08-2009, 06:19 PM	#3
Scoobyslack1 Scooby Specialist Member#: 2780 Join Date: Oct 2000 Chapter/Region: MWSOC Location: back in Chicago Vehicle: junk yards rule! Project FrankenSTien	Is the new harness for the new motor? Will it replace the whole front harness? Stretch out the harness on the floor & label everything you can find. Go through and find everything you will need to splice. Write out what wires go together. It will help keep it straight instead of trying to read the diagrams while splicing. Also, if the is anything you don't need (AC, ABS, etc.), find those wires and remove them. That will help keep it cleaner.