I can't seem to find a concrete answers to this, but long story short, I have a race coming up this weekend and I live on an island where no auto parts store has an alternator is stock, and most likely would not arrive on time anyways. I do however have a few used NB alternators on hand that I'm considering to use. I know the NA ones have a built in regulator and the NB's are controlled via ECU, and I also know the MS3pro allows you to regulate the voltage as well.

My question is, is it a matter of just swapping the NB alternator in and changing a few settings in tunerstudio? Or will I have to splice a few wires to correct the outputs? As a temporary solution I'd rather not splice anything and just miss the race, but if I can just hot swap and change a few settings, I can make my race.

 

On NAs, the small white/green wire is fused power, the white/black wire is the ground light for the charge light to turn it on/off when batt V is below/above 12 volts or whatever the regulator's set to.

On NB2s, the grey wire goes to 4t, the grey/red wire goes to 3M. According to Link's wiring pinout, the grey/red wire is your alt control wire, looks like they don't utilize 4T, they just call it "alt voltage".

So wire the grey/red to an output on your MS that you can select in the "control output" drop down menu of the alt control page. Download a NB2 basemap to get the rest of the settings.

 

@curly how about the opposite situation?

Im in a similar position but the exact opposite. Nb2 chassis with ms3pro and pro dash. Having alt issues and want to try a na or fdrx7 alternator.

Can I just ommit the 2 pin connector or do they need something other than the main power wire?

 

You'll want to feed the white/green wire 12v at least, that's it's regulator input. Without it, you may have to rev the car to 3-4000rpm to excite the alternator into charging.

 

Could you just jump a wire off the main lug?

Or switched power I assume?

 

I've seen it wired off off the main lug, yes. I really don't have experience to tell you why that's a bad idea, besides the fact that Mazda didn't wire it that way, probably for a reason. Just to fuse it below the 80amp main fuse maybe? The main lug is also going to be the "best" voltage you'll see I imagine, if you get any voltage drop what soever, you'd see it after any relays, fuses, or loads.

 

I have been running a RX7 alternator for years now without any issues.
...do what curly says and you should be fine.

There are a couple of things to note though.

1. The RX7 alternator I'm using doesn't have the captured nut in the lower mount, so I found a longer bolt that went all the way through both mounting tabs with a nut on the other side. It's just a minor inconvenience.
2. The alternator itself is a bit fatter than the NB alternator and may interfere with the upper bracket. You may have to notch it (the bracket) a little to get full range of adjustment YMMV.

Good luck with that.
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