Combining different wiring harnesses

[maclonchas]

Folks,

I am looking for some advice and guidance here as I do my upfront planning for ordering an 818C. First, I do not plan on using a donor. Basically, I am not thrilled by having more parts to get rid of and most of the cars lately are pretty banged up or are outrageously expensive.I have exhausted myself on the engine trades and believe the H6 is off the table and will go with a JDM EJ205 with AVCS and TGV (delete or not?) with a tuned JDM ECU for a pre 2005 WRX. This leads me to the wiring harness dilemma. I have read a lot about the immobilizer, cutout switch, antenna and key and I really do not want have that trail to muddy the build.

Here is my question with all that background. If I use the engine wiring harness from a 2004-2005 JDM EJ205 (no mobilizer), a bulk wiring harness from a USDM 2006 WRX and the other harnesses rear, fuel tank, etc., am I going off the cliff? Will this work with a tune of the ECU?

Thanks for your help.

Bill

[Ajzride]

The immobilizer requirements are determined by the ECU, not by the harness. If the 2004 JDM ECU does not require an immobilizer, then you won't need it. I don't think anything that old requires an immobilizer, at least in US the 2006 WRX was the first immobilizer. For the chassis harness, I highly recommend getting a system from Coach Controls or American Autowire. It will be much cleaner and more capable than trying to wade through an OEM harness. I am using the Coach-1 for my chassis with a 2006 WRX Engine Harness + ECU and wiring has been surprisingly pleasant for my project.

https://coachcontrols.com/index.php?main_page=product_info&cPath=36&products_id=123

[maclonchas]

Ajzride,

Thanks for the input and direction. I was definitely asking the problem and solution much harder than it needed to be for this project. If I understand you correctly, using a Coach-1 as the main harness (dash, lights, turn signals, fuel pump, locks, etc.) and coupling that with a dedicated Subaru engine harness with a matching ECU for the JDM engine. I can either use the JDM engine harness or USDM wiring harness with the IWire or IA Performance AVCS add.

Does that sound about right?

Thanks

Bill

[Ajzride]

Yes that is correct.