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Alternator Light in Cluster

 
Old 11-11-2009, 12:13 PM
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Default Alternator Light in Cluster

hi guys

i am running an e420c in my NB-B 2001 model.

after i wire it all up, i am getting a battery warning light litted in my dash.



with a multimeter, i checked the charging on the battery.. and it is perfect, 13.5Vs.

does anyone have a clue why i could be getting a battery warning light in the dash?

i checked the wiring diagram and everything related to the alternator is connected.
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Old 11-11-2009, 01:02 PM
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I could be completely off base, but isn't there something weird about the NB charging circuit? I seem to recall reading through some megasquirt threads and people needing to build an additional circuit to control the alternator, or switch to an NA Alternator.
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Old 11-11-2009, 04:46 PM
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The stock ECU needs IAT signal.

End of the thread.
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Old 11-11-2009, 05:14 PM
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Originally Posted by ismael_pt View Post
The stock ECU needs IAT signal.

End of the thread.
Not saying i dont believe you but im here to learn a bit more about the mazda community and if you dont mind could you please explain why the batt light came on for a iat sensor?

I dont quite understand the op's post fully either.
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Old 11-11-2009, 05:35 PM
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Originally Posted by Tw34k View Post
Not saying i dont believe you but im here to learn a bit more about the mazda community and if you dont mind could you please explain why the batt light came on for a iat sensor?
It's a tad silly, but the field coil in the '99 and later alternators is controlled by the stock ECU, rather than by an internal regulator. If the OP was using the stock ECU (such as in a parallel configuration) then it's true that a lack of IAT signal would prevent this circuit from operating properly, however I'd expect it to go into "limp" mode and throw CEL, rather than lighting up the battery icon.

Now, the OP didn't tell us whether he was running parallel or not, but I can't think of a reason why you would with an e420c.


On the NBs, the light in question is controlled not by the alternator itself, but by the ECU. Sadly, I do not have a complete wiring diagram for a 2001 (2000 is the latest I've got for the instrument cluster) however I think that it's the Brown/Red wire at pin 3U of the 2001 ECU. So check out that wire, see where it goes. If you've grounded it for some reason, then the light will come on.
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Old 11-11-2009, 05:46 PM
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Thats more like the kind of answer im looking for.
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Old 11-11-2009, 07:48 PM
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thanks for the fast response and informative replies.

the IAT on the stock ECU is not connected as i have only connected the GM IAT to the e420c. i was only of the opinion that the missing IAT would probably trigger a CEL, which has been there for ages, so did not bother about it.

the e420c is running in parallel.. i will try out the IATs and hopefully it resolves that problem.

on a sidenote, does anyone have problems with datalogging on Wari latest software? i clicked log, but nothing happens.
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Old 11-11-2009, 10:35 PM
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it works! alternator light is gone after i wired up the resistors going into IAT back to original ECU.

thanks guys.... now only left with

P0107 barometric sensor

do the rest of the adaptronic guys with 02 miatas have the CELs on all the time?

Last edited by joel1188; 11-11-2009 at 11:06 PM.
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