Wrong NB8A Alternator??

[KevGoat]

Need some assistance here ...

I think I've stumbled across my NB8A's battery warning light issue - an incorrect alternator fitted. Mine has had a re-manufactured alternator fitted at some stage that looks different to the stock ones. I think this one might be internally regulated, throwing the ECU in to a hissy fit.

I have no charging problems, no low battery problems and voltages check out fine. Just that the instrument panel warning light comes on about 10/15 seconds after engine start and stays on.

According to the following diagram from Miata.Net, by re-directing the two wires from the alternator, this will fix the warning light issue. Original mod was to allow an NA alternator to be fitted to NB's. As this would be a much cheaper alternative to purchasing a new genuine alternator, I figured I'd give it a try, but wanted to check here first. Has anyone tried this on their NB? Would this create other issues with the ECU? Should I just buy the proper alternator?

Miata.Net mod:



The alternator currently fitted to my car:




What the original looks like (part No BP4W-18-300R-0C)

[KevGoat]

In answer to my own question...It works!

The above wiring diagram corrects the battery warning light with an IR Alternator fitted. I obtained another two pin plug (fairly common plug) for the alternator so that I didn't have to cut the original wires and can return to stock alternator easily.

[Old Dude]

Good job Kev, you really are sorting that NB out aren't you

Cheers
Dale

[KevGoat]

Gettin' there Dale

This car was meant to be the easy one after Mexie

Friends of mine, who have known the previous owner for a long time, all said he was so particular and finicky about the car! Yet as I've been taking things apart to find answers to problems, I've found that he did some strange (and potentially dangerous!) things and left so much unfinished.

Ah well, makes the car all the more satisfying and personal as I get it all fixed .... Really like this model. Great car