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01-02 vs 03-05 engine harness

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Old Nov 19, 2025 | 09:01 AM
  #1  
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From: Canada
Default 01-02 vs 03-05 engine harness

Hello, a few years back I had my 2003 K swapped. Unfortunately due to some design and support flaws I'm putting it all back to stock and will be running a rotrex.

My problem is this, I am not sure if I "need" to get the engine wiring harness from an 03+ or if any NB2 harness will work.
I'm buying an engine with harness from the UK so not sure which year it's going to be.

I've been talking to support at BeerMoneyMotorsports for their ecu and at least on their end it's just a jumper to change from 02/03.
But I've also seen things on this site where people were saying the wiring is completely different between the years.

A megasquirt looks like it's all the same from 01-05 so that adds to the confusion.

Do I need to match the ecu to the engine harness or to the chassis?

Thank you.
Old Nov 19, 2025 | 10:38 AM
  #2  
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I dont have anything to add about Beermoney. Only a data point that my daily driver is an 04' (non msm) running perfectly fine on a 01-05 MS3 Pro.

Are you wanting to go with Beermoney for cost savings or? I've heard little about BMM, but looking breifly at their offerings they dont seem to offer much else than what the ms3 does. Internal o2 sensor is nice I guess.
Old Nov 19, 2025 | 10:43 AM
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Thank you for the data point. I think the main issue is if the engine I get has an 01-02 harness is that going to cause an issue.

The BMM is what my tuner recommended with the MS3 being close 2nd. Said he liked it a bit more than MS3 and if it's cheaper then great. Option for DBW is nice as well.
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