2 replies to this topic

[Todd Green]

By any chance does anyone have the wiring diagram for the X-04 connector in a 2003 VVT?  It's a white 54 pin connector that mates the ECU harness to the dash (basically like the X-16 connector in 99's (for which I can find a zillion diagrams)  Pic of the connector attached.

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[Todd Green]

Just to answer this myself, as best I can tell after scouring the 'net (and even after calling Mazda Motorsports) the X-04 connector isn't directly documented.   We had to trace the wires individually backwards from where they went.    This was complicated by the motor being a JDM and the harness being a used US one (since the JDM harness was chopped when they shipped it).   Unfortunately not all the wire colors matched our harness in the online wiring diagram PDF's we could find which is always fun.   Finally the clutch bypass seems to be different on the NB's than the NA's.   Or at least the clutch bypass that the PO of my car had done didn't work on the JDM ECU, so we had to find the wire on the ECU for that as well.   (We did not have to do this for the clutch with the previous JDM '99 1.6 that was in the car.)

 

The good news is that it is running. 

[Todd Green]

And hopefully this saves someone a few days of their life researching, but I got OBDII working on the JDM ECU.  (I'm guessing it's the same on the US model).  Obviously if you have an NB chassis you don't have to do this but for a pre-OBDII NA, signal is pin 3Q on the ECU, but I tapped the X-04 connector via the G/W (Green with white stripe) wire.  One thing that was confusing is that the OBDII connector I got from Amazon was wired with signal on pin 2.  But that is for a different SAE J1850 standard and 2003 Miatas use ISO 9141-2 via pin 7 (K-Line also referred to as KLN in the FSM).  The L-Line isn't used.  Pins 4&5 go to ground and pin 16 is 12v (power).  Used an OBDLink LX bluetooth scanner and my phone with a free app.