[Aaron]

If it's anything like the IMMOB function in a Chrysler Neon there's a single pin on the ECU that puts it into IMMOB mode - on Thatchcam cars (UK Market) and cars with the full on factory alarm system it's triggered.

I suspect Mazda may be the same as the GTX was sold in the UK and it wouldv'e probably needed something similar, however it may also be electronic trickery.

Have you thought of trying an alternative ECU? It could just be a dead injector circuit?

A.