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Old 06-13-2016, 08:40 AM   #1
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Default How did I screw up my NB charging system??

I brought my 99 NB back to pseudo-stock and passed emissions. Charging was no issue, but I would see the battery light occasionally on very low idle. I was sorting through the A/C system and did the following operations:

1) Realize that I had left the evaporator plug apart - reconnected it
2) Checked the 2 A/C relays - plugged them back in
3) Plugged the cigarette lighter back in - was out from the last time I had the console off. I had to fish the connector out with my fingers.
4) Did several A/C runs - got the pressure where I wanted

All of these operations, I did with the battery still connected, because I'm lazy.

Somehow, all of this has eliminated the alternator's ability to charge.The battery light now comes on a few seconds after starting,

Battery holds 11.2V and falling. Same at the alternator post.

Changed to a new Advance alternator. Same story.

Swapped over to my Megasquirt that has a handmade alternator regulator - no charging.

Spent a little time polishing up grounds and adding an alligator clip to ground the alternator case - that did nothing.

I removed the engine bay fuse block and looked at the white wire - looked good, but I did not unscrew the main fuse yet and really inspect the white cable.

So - I think this means
1) It's not a blown voltage regulator in the stock ECU
2) It's not the alternator, unless I bought another bad one

I am guessing that there is maybe an open in the 2 signal wires from the alternator to the ECU?
Did there just randomly break? Should I run a continuity check back to the ECU?
Is there a way to bypass this ECU control - I guess not, without an NA alternator transplant?

Did I short a cell in the battery when I plugged in the cigarette lighter?

Did I break something in the signal wires? How?

What should be my next step?

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Old 06-13-2016, 08:45 AM   #2
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is it plugged in?
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Old 06-13-2016, 09:35 AM   #3
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For sure. The old alternator produced no charging, before I ever touched it or the ECU.
It was working until it didn't.

When I changed the alternator, I plugged the new one in.
I later unplugged it, checked the wires, and plugged it in once more.
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Old 06-14-2016, 03:37 AM   #4
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Did you have the parts store check the old one or new one to make sure it's not a bad run of alt?
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Old 06-16-2016, 07:56 AM   #5
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*** Update ***

Took the battery back to the parts store. Charged and tested good.
Resting voltage: 12.48 VDC
Idling voltage: 12.05 VDC

I did not yet reconfirm that it is only 12.05 VDC at the alternator terminal, but I am sure that is the case.

I think that leaves:
1) Possible bad new alternator
2) Disconnect in the 2 signal wires to the ETU

Are there any other possibilities?

What are my options for getting out of this mess with an internally regulated alternator?
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