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Broken alternator wire, no red warning light. ??
Posted by: nnsquared ()
Date: October 17, 2011 01:46AM

LM converted to internal regulator by PO. Spectator at car show found the broken field wire in the 2-wire plug in the alternator. Seems like there should be some indicator light on. Maybe could have broken it during cleanup, after I parked. Maybe only one strand there and already ready to break, but maybe not. Anyone want to tell me, in laymans electrical language, what is going on? Thanks in advance.

Won 2nd place in racer class at big fall meet of Historical Car Club of PA.

Regards,
Kerwin,
Valley Forge, PA
65 Monza 110 PG, Stinger wannabe SW 001


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Re: Broken alternator wire, no red warning light. ??
Posted by: MattNall ()
Date: October 17, 2011 01:56AM

1 strand is enough to supply Voltage... No CURRENT goes to the Field... to speak of.


I've flashed the field of a GM alt with a 9 volt battery..





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Re: Broken alternator wire, no red warning light. ??
Posted by: nnsquared ()
Date: October 17, 2011 02:03AM

So, Matt, you are saying it wouldn't have enough juice to charge, but would have enough to keep the light off? I did have some indication of weak battery over he past couple of months, but it always started, and also had some normal starts. Related to single strand deal?

Regards,
Kerwin,
Valley Forge, PA
65 Monza 110 PG, Stinger wannabe SW 001


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Re: Broken alternator wire, no red warning light. ??
Posted by: MattNall ()
Date: October 17, 2011 02:11AM

Yup!! run into that a few times... dirty connection or broken strands... low voltage to the Field...

So it charges enough to turn off the light..but not make the 14.3 needed...

12 volts will maintain a battery..but not recharge...





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
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Re: Broken alternator wire, no red warning light. ??
Posted by: cnicol ()
Date: October 17, 2011 02:16AM

An internally regulated alternator does not have a "field" connection.

There are two wires:

The "exciter" wire - when you switch on the key, 12v is applied here to "kick-in" the alternator. If there's enough residual magnetism in the alternator, it will start working (at a higher rpm) without this wire. Once things are running, this wire operates the idiot light should the alternator stop working.

The other wire is the "sense" wire, which is supposed to run back the the positive battery post (or thereabouts). I don't know how the alternator would react with this disconnected. I *think* it might work OK using an assumed voltage at the battery.

It wouldn't surprise me at all if the alternator worked with one of these wires broken, in fact a true "one wire" alternator does eliminate these wires with a little design tweak in the regulator.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
66 Red Monza 2dr 140/4 EFI 60k
61 Seamist Jade Rampside 140 PG
65 Cypress Green Monza 140/4 4dr
65 White 4-dr 110/AC/PG (parts)



19 Tons of parts in boxes

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Re: Broken alternator wire, no red warning light. ??
Posted by: acardon ()
Date: October 17, 2011 02:37AM

Quote

broken field wire in the 2-wire plug in the alternator

The #2 wire is the voltage sense as Craig said. Without the sense wire connected, the alternator will overcharge or run wide open. Usually 15 to 17 volts, which won't cause any imediate problems, but will gradually overcharge the battery. The first indication is the smell of the acid in the battery boiling.
A one wire alternator had the #2 terminal connected to the alternator output inside the regulator to sense voltage and the regulator has a circuit to sense rotation to excite the alternator, although it usually takes more than idle RPM to get a one wire alternator to start chargeing.

The Trunk Belongs in Front, Ask Any Elephant
Caution: Images in This Mirror May be Waterpumpers
Don
NTCA....DFW,TEXAS
66 Monza 1 owner

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Re: Broken alternator wire, no red warning light. ??
Posted by: MattNall ()
Date: October 17, 2011 02:37AM

Craig... I think he means the R-F plug in a stocker...

Kerwin???





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Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
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Re: Broken alternator wire, no red warning light. ??
Posted by: cnicol ()
Date: October 17, 2011 02:40AM

MattNall Wrote:
-------------------------------------------------------
> Craig... I think he means the R-F plug in a
> stocker...
>
> Kerwin???

Craig replies: I think it's a 10SI. (Quote 1st post: "LM converted to internal regulator by PO.")

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
66 Red Monza 2dr 140/4 EFI 60k
61 Seamist Jade Rampside 140 PG
65 Cypress Green Monza 140/4 4dr
65 White 4-dr 110/AC/PG (parts)



19 Tons of parts in boxes

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Re: Broken alternator wire, no red warning light. ??
Posted by: ElkyBob ()
Date: October 17, 2011 02:41AM

I believe one of those wires in the 2 wire plug goes to the dash for the dash light or voltmeter. So, if the wire was broken you would get no dash light, etc.

Bob Ponder in Tenino WA


1962 Vair Vert/102 4 spd w/EFI
1959 El Camino w/348 5 speed
1987 El Camino w/350 auto
2000 Ford F150
2014 Honda Crosstour

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Re: Broken alternator wire, no red warning light. ??
Posted by: MattNall ()
Date: October 17, 2011 02:44AM

FROM OUR FAQ'S







MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
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Re: Broken alternator wire, no red warning light. ??
Posted by: cnicol ()
Date: October 17, 2011 02:46AM

Matt, that's an 8DN externally regulated alternator. His has an INTERNAL regulator.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
66 Red Monza 2dr 140/4 EFI 60k
61 Seamist Jade Rampside 140 PG
65 Cypress Green Monza 140/4 4dr
65 White 4-dr 110/AC/PG (parts)



19 Tons of parts in boxes

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Re: Broken alternator wire, no red warning light. ??
Posted by: MattNall ()
Date: October 17, 2011 02:53AM

But he says FIELD.... Internals have 1 & 2, not R & F.....


And I missed the first 6 words!!! gggg... lousy speed reading doesn't always work!! gg





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Broken alternator wire, no red warning light. ??
Posted by: nnsquared ()
Date: October 17, 2011 01:31PM

Thanks for the info.
First, the alternator. No external regulator. 2 wire plug at the 12 oclock position. Alt is marked 1, ?(it's in the garage, I'm in the house), 2 is marked F. White wire to 1, blue wire to 2. Fat red wire, 8 oclock, to the funny red terminal block on the rail at the pos side of the battery.
No indication of battery boiling or anything other than just working. Occasionally it acts like low voltage because the starter turns,hesitates for a half second, then cranks and engine starts quickly. Gen/fan light flickers when at idle in gear (PG) at 6-700. Goes out at 800 in neutral. Actually, it all seemed pretty normal until the guy said my wire was broken. I clipped a jumper wire on it to connect, and drove home for half hour, all as normal.
I am going to fix the wire, no other work, unless you guys have something that I really ought to do.
Thanks again.

Regards,
Kerwin,
Valley Forge, PA
65 Monza 110 PG, Stinger wannabe SW 001


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Re: Broken alternator wire, no red warning light. ??
Posted by: acardon ()
Date: October 17, 2011 02:10PM

Check the output voltage of the alternator and this is the handiest electronic device I have used since the microwave. It plugs into the cigrette lighter and gives a real time indication of your electrical system. .....VOLTMETER.

The Trunk Belongs in Front, Ask Any Elephant
Caution: Images in This Mirror May be Waterpumpers
Don
NTCA....DFW,TEXAS
66 Monza 1 owner

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Re: Broken alternator wire, no red warning light. ??
Posted by: cnicol ()
Date: October 17, 2011 02:36PM

Like Don wrote, check the output voltage. I'm suspecting a weak alternator (low current capability) and possible a weak battery too. The generator light shouldn't be flickering at idle with an alternator in a stock Corvair.

I would want to get to the bottom of the issue, so after repairing the wire and cleaning the battery posts, I'd test both the battery and the alternator. It's confusing because the triangle of battery/starter/generator (and usually regulator) are all related and dependent on each other. One weak element creates symptoms in the others and it can be a little confusing to sort out which is the bad guy (or two). The only real way to get to the bottom of the issue is to performance test each piece.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
66 Red Monza 2dr 140/4 EFI 60k
61 Seamist Jade Rampside 140 PG
65 Cypress Green Monza 140/4 4dr
65 White 4-dr 110/AC/PG (parts)



19 Tons of parts in boxes

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Re: Broken alternator wire, no red warning light. ??
Posted by: Andrew ()
Date: October 17, 2011 06:50PM

My van was converted to a stock externally regulated alternator setup by the PO. Earlier this year I had to replace the stock mechanical regulator with a solid state one. This was after it overcharged and blew the caps off the battery. The mechanical regulator was damaged by rust across the back of it. I don;t know what they're called off-hand, they're the sprial wrapped fuse looking deals. A couple of weeks ago I had a dead battery the day after I drove home with the headlights on. Charged up the battery, started it back up and found that the alternator wasn't charging. After an inspection I found that the red wire going to the battery was corroded inside the rubber boot, and had broken loose. When I tried to loosen the nuts, the stud broke. I bought a replacement alternator from the FLAPS and swapped all the guts over into my Delco Remy case. It works fine now. However, the two times before it died (when the BAT wire was disconnected) the idiot light never came on. It lights up with Key On Engine Off, or if I remove the belt. I wondering the PO somehow screwed up the wiring in the conversion process.

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Re: Broken alternator wire, no red warning light. ??
Posted by: acardon ()
Date: October 17, 2011 07:25PM

Quote

However, the two times before it died (when the BAT wire was disconnected) the idiot light never came on. It lights up with Key On Engine Off, or if I remove the belt.

The idiot light will not come on if the alternator is charging but is not connected to the battery. The #1 termional is looking at alternator voltage.
That's the reason a voltmeter is so useful. You can tell the condition of the battery, by watching the voltmeter while cranking. If the voltage drops below 9 or 10 volts while cranking, the battery could be weak or there is a bad connection at the cables. A fully charged battery is 12.6 volts, if it's below 12 volts, without any load, it's not holding a charge. If the alternator isn't putting out from 13 to 14.5 volts, it has a problem and is not chargeing the battery.

The Trunk Belongs in Front, Ask Any Elephant
Caution: Images in This Mirror May be Waterpumpers
Don
NTCA....DFW,TEXAS
66 Monza 1 owner

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