Alternator and regulator connections - Alfa Romeo Bulletin Board & Forums

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post #1 of 13 (permalink) Old 03-18-2017, 03:03 PM Thread Starter
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Alternator and regulator connections

Doing the final connections and checks on my electric system, and I have run into an issue.

I do have a wiring diagram, but my alternator doesn't have any indications on the connectors and the regulator does not match the wiring diagram. My charge light remains on when starting the car, and it doesn't charge. Before starting to replace parts, I need to make sure how to connect the parts.

Any help for dummies (... who did not label the wires when disassembling the car...)?






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post #2 of 13 (permalink) Old 03-18-2017, 04:34 PM
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the alternator in the photo looks like it has an internal regulator. the regulator in the photo is an ancient "modular" three wire type. your harness should have three wires to the old alt. (not counting the fat red ring terminal main wire) the harness at the old reg. will also have three wires, but one of them will be double, that's the one that connects to the dash indicator, the single spade on the new alt.

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post #3 of 13 (permalink) Old 03-18-2017, 04:55 PM Thread Starter
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Does that mean that I do not need the external regulator?

The wiring harness between the 2 units was a complete mess, and I have made a new. As you mention, I have the green from the indicator light and the thicker red to the battery positive. In addition I have another green piggybacking between the 2 units, a black and a brown.

If I understand you right, I only need to connect the red to the bigger terminal on the alternator and the green on the one with the spade connector, but not reinstall the old regulator and leave the brown and black off the car. Is that correctly understood?

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post #4 of 13 (permalink) Old 03-19-2017, 06:06 PM Thread Starter
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Anyone else? I am kind of stuck here.

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post #5 of 13 (permalink) Old 03-20-2017, 12:42 AM
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Quote:
Originally Posted by kitora View Post
If I understand you right, I only need to connect the red to the bigger terminal on the alternator and the green on the one with the spade connector, but not reinstall the old regulator and leave the brown and black off the car. Is that correctly understood?
yes, I think its correct
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post #6 of 13 (permalink) Old 03-20-2017, 07:56 PM Thread Starter
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So a little progress. I connected the green wire from the charge light in the dash to the spade terminal and the red wire from the battery to the 6 mm terminal on the generator. Now the light in the dash (kind of) turns off when the car is started. "Kind of" is probably because I might have put in a higher wattage bulb. Does anyone know if an LED can be used? I have used LED bulbs for the rest of them, and the light is great from them.

One problem that remains is that the generator still doesn't charge the battery. The voltage is 11.8V whether the car is running or not. Do I need to add a jumper to the other terminal on the generator from one of the 2 wires connected?

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post #7 of 13 (permalink) Old 03-21-2017, 06:09 AM
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First: what alternator or generator are you using?

Second: did you try revving or driving the car?

I swapped to an internally regulated Bosch and found that the (internal) regulator didn't do its thing correctly until I revved it up over maybe 2500 RPM. This was during my break-in run so I don't have a lot of experience with how it behaves past that.

Re bulb: I asked a similar question on another thread and learned that using the factory wattage bulb is important to not only the function of the green "GEN or ALT" light but also to the internal regulator of the alternator. Swap the original bulb in, give it a blip of throttle and tell us how it works.

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post #8 of 13 (permalink) Old 03-21-2017, 07:09 PM Thread Starter
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I did try revving the car, and it doesn't charge at any revs.

The bulb is now the original one, but the car is still not charging. I am completely lost here, and might have to go and buy a new alternator. However, isn't there an easy way of testing the alternator?

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post #9 of 13 (permalink) Old 03-21-2017, 08:09 PM
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Presume you check for continuity between the green wire you connected to the alternator and the dash gauge or dash gauge connector? No funny business where the voltage regulator was spliced in before?

No problems with the dash grounds?

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post #10 of 13 (permalink) Old 03-22-2017, 12:33 AM
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start de car and measure at the output of the Alt (where the big red wire goes to) the voltage, if below 13V trash it
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post #11 of 13 (permalink) Old 03-22-2017, 09:38 AM
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Hold on a sec... if the regulator is not getting the signal it needs, the alternator is not going to know what voltage to put out. I would do a lot more digging on the regulator circuit, which relies on the dash bulb and therefore dash grounds and associated wiring before trashing the alternator.

I'd also make sure your battery is correctly charged before attempting this.

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post #12 of 13 (permalink) Old 03-24-2017, 10:35 PM Thread Starter
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Thanks for all the advice. I have decided to take the parts to O'reileys tomorrow and have them test the functionality, before throwing anything in the trash can.

The battery is brand new and fully charged, so no issues there.

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post #13 of 13 (permalink) Old 03-27-2017, 06:15 PM Thread Starter
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An update: O'reiley's couldn't test anything not installed in the car, so I bought a new 85A alternator from BNR parts on ebay. Bought it Saturday and it arrived today Monday. Great service!

Installed it, and it works like a charm.
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