It seems that the 2001-2005 JDM ECU is wired differently from the USDM/EUDM ECU.

I recently bought a 2001-2005 MS3 Basic from Reverant for a friend running a Japanese 2002 engine, harness and ECU (in an NA8 M2 1028). We hooked it up but the fuel pump didn't prime. Looking at the wiring of the ECU (and with some help from Reverant) it is clear that the Japanese ECU uses pin 2O (lime green wire) for the fuel pump rather than 2M (red/white) like other countries.



The simple fix was to solder a jumper between pins 2O and 2M inside the ECU. The two pins are shown here with red arrows.

Looking through the wiring diagrams I couldn't find any other major differences between the different countries ECU wiring and this slight modification had the car running perfectly on the MS3.

I wonder why Mazda used a different pin for the fuel pump in different countries...

 

Cars with immobilizer have the fuel pump on 2M
Cars without immobilizer have the fuel pump on 2O.

Similar to 99-00 euro cars where they also use a different wire for cars with or without immobilizer

 

Ahh, that makes more sense.
So it's nothing to do with the country of manufacture (although I suspect that there are more cars made without immobilizers in Japan).

I believe that the pin-out image I posted was one of yours.
Thanks!

 

Can you post pics of the M2-1028? My favorite Miata