alternator wiring

E

ek_lektro

New member
Jul 27, 2007
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Greetings GMC friends;
a couple years ago I was having problems with an alternator putting out 16.5 volts and blowing headlights (a problem that seemed to start when i had an anonymous mechanic do an alternator swap for me). Back then, somebody on this list gave me a step-by-step process to check and make sure that the 2 wires on the left side were not reversed. I can’t seem to find this email, so if anybody here could remind me of the process, i’d greatly appreciate it! (Also,. i recall reading here somewhere that having a loose wiring connection with an APC circuit inline could also cause high voltage output from the alternator?) Just trying to get to the bottom of this… once and for all! Thanks much,
Greg
’78 Eleganza II
and ’76 Birchaven cut-down 21 footer
(might consider selling! can’t keep up with 2 coaches...)
 
I am just trying to see how they could possibly be reversed. The wires are in a connector that is keyed so that it can only go into the alternator one way.

Here are your step by step instructions:
1 grasp connector
2 try to slide the connector into the alternator.
3 if it doesn’t fit go to step 4
4 turn the connector 180 degrees and plug it in!

Unless he pulled the wires from the connector — but what kind of mechanic would do that?

If your voltage sense wire has a loose connection
It could be read as low voltage and cause the voltage regulator to step up the charge voltage. This could happen whether you have an APC or not.

Emery Stora
77 Kingsley
Frederick, CO

>
> Greetings GMC friends;
> a couple years ago I was having problems with an alternator putting out 16.5 volts and blowing headlights (a problem that seemed to start when i had an anonymous mechanic do an alternator swap for me). Back then, somebody on this list gave me a step-by-step process to check and make sure that the 2 wires on the left side were not reversed. I can’t seem to find this email, so if anybody here could remind me of the process, i’d greatly appreciate it! (Also,. i recall reading here somewhere that having a loose wiring connection with an APC circuit inline could also cause high voltage output from the alternator?) Just trying to get to the bottom of this… once and for all! Thanks much,
> Greg
> ’78 Eleganza II
> and ’76 Birchaven cut-down 21 footer
> (might consider selling! can’t keep up with 2 coaches...)
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Let me re emphasize what Emery said. The APC is NOT a source of the potential problem. It is the connection to the alternator which is a female
spade connector spade that could be on the APC or on the cable if no APC is installed.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
If someone has replaced the connector at the end of the alt wire it is
quite possible the wire spades got switched when inserted into the new
connector body. Seen that.

Sully
77 eleganza 2
Bellevue

> Let me re emphasize what Emery said. The APC is NOT a source of the
> potential problem. It is the connection to the alternator which is a female
> spade connector spade that could be on the APC or on the cable if no APC
> is installed.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Those connections are not weather tight and subject to oxidation especially on vehicles that sit long periods. I have recommended Caig Deoxit D5 spray
in the past for such uses. Also do not rule out a bad connection at the isolator or bad isolator, but check what others have said first.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Thanks for the suggestions everybody,
and here’s a bit more clarification:

> If someone has replaced the connector at the end of the alt wire it is
> quite possible the wire spades got switched when inserted into the new
> connector body.

yes, apparently the previous owner had an issue this connector,
because i only have 2 individual spade connectors… which are easy to accidentally reverse!

> Those connections are not weather tight and subject to oxidation

yes! especially without the connector casing...

> If your voltage sense wire has a loose connection
> It could be read as low voltage and cause the voltage regulator to step up the charge voltage. This could happen whether you have an APC or not.

OK, so i will definitely clean up or all-out replace the spade connectors.

So... the step by step directions i got last time (if i recall correctly?) involved checking voltage and alternator light status during pre-ignition and ignition, to make sure that the 2 individual spades are hooked up to the correct alternator terminal. Anybody know the procedure?

And this time i will take care to label these spades so this never happens again!

thanks much! cheers,
Greg
 
Or you could go to the "help" rack at your local auto parts store and buy
the correct pigtail with a captive prong (to keep the plug from falling
out) which you can then either splice in or remove the wire tails and put
your female spade connectors into. More sanitary.

Sully
77 eleganza 2
Bellevue

> Thanks for the suggestions everybody,
> and here’s a bit more clarification:
>
> > If someone has replaced the connector at the end of the alt wire it is
> > quite possible the wire spades got switched when inserted into the new
> > connector body.
>
> yes, apparently the previous owner had an issue this connector,
> because i only have 2 individual spade connectors… which are easy to
> accidentally reverse!
>
> > Those connections are not weather tight and subject to oxidation
>
> yes! especially without the connector casing...
>
> > If your voltage sense wire has a loose connection
> > It could be read as low voltage and cause the voltage regulator to step
> up the charge voltage. This could happen whether you have an APC or not.
>
>
> OK, so i will definitely clean up or all-out replace the spade connectors.
>
> So... the step by step directions i got last time (if i recall correctly?)
> involved checking voltage and alternator light status during pre-ignition
> and ignition, to make sure that the 2 individual spades are hooked up to
> the correct alternator terminal. Anybody know the procedure?
>
> And this time i will take care to label these spades so this never happens
> again!
>
> thanks much! cheers,
> Greg
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Posted from Emory's alternator issue.

I also had a 6 month old NAPA alternator that was putting out 18 volts.
Had it tested at NAPA and it tripped out the test equipment twice.
Got a new alternator on warranty.

My plug from the APC would could go on either way. I replaced with new
connector cover so it fits only in the correct position.

https://www.napaonline.com/en/p/ECHVRC148

> Or you could go to the "help" rack at your local auto parts store and buy
> the correct pigtail with a captive prong (to keep the plug from falling
> out) which you can then either splice in or remove the wire tails and put
> your female spade connectors into. More sanitary.
>
> Sully
> 77 eleganza 2
> Bellevue
>

>
> > Thanks for the suggestions everybody,
> > and here’s a bit more clarification:
> >
> > > If someone has replaced the connector at the end of the alt wire it is
> > > quite possible the wire spades got switched when inserted into the new
> > > connector body.
> >
> > yes, apparently the previous owner had an issue this connector,
> > because i only have 2 individual spade connectors… which are easy to
> > accidentally reverse!
> >
> > > Those connections are not weather tight and subject to oxidation
> >
> > yes! especially without the connector casing...
> >
> > > If your voltage sense wire has a loose connection
> > > It could be read as low voltage and cause the voltage regulator to step
> > up the charge voltage. This could happen whether you have an APC or not.
> >
> >
> > OK, so i will definitely clean up or all-out replace the spade
> connectors.
> >
> > So... the step by step directions i got last time (if i recall
> correctly?)
> > involved checking voltage and alternator light status during pre-ignition
> > and ignition, to make sure that the 2 individual spades are hooked up to
> > the correct alternator terminal. Anybody know the procedure?
> >
> > And this time i will take care to label these spades so this never
> happens
> > again!
> >
> > thanks much! cheers,
> > Greg
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
 
thanks for the link Bruce
>
> https://www.napaonline.com/en/p/ECHVRC148 https://www.napaonline.com/en/p/ECHVRC148
I greatly appreciate all the tips on the integrity of the connections, and replacing the missing connector,
and i’ll make that part of my fix!
But first i do need to confirm 100% that the 2 wires are going to the 2
proper terminals. i’m fairly sure that this time they’re connected correctly,
and that the 16.5v might be due to a borderline poor connection
(but after a quick clean-up i’m still seeing 16.5)...
So… I could really use the info on that testing “procedure”, if anyone recalls how to do it.
(Maybe it was a Jim Bounds testing trick, dictated over the phone (?)
but i figured i’d try here before i bothered Jim, again!
thanks everybody,
Greg
 
Was this it?
Read here
http://www.gmcmhphotos.com/photos/data/15/GMC_charging_system_checkout.pdf

> thanks for the link Bruce
> >
> > https://www.napaonline.com/en/p/ECHVRC148 <
> https://www.napaonline.com/en/p/ECHVRC148>
> I greatly appreciate all the tips on the integrity of the connections, and
> replacing the missing connector,
> and i’ll make that part of my fix!
> But first i do need to confirm 100% that the 2 wires are going to the 2
> proper terminals. i’m fairly sure that this time they’re connected
> correctly,
> and that the 16.5v might be due to a borderline poor connection
> (but after a quick clean-up i’m still seeing 16.5)...
> So… I could really use the info on that testing “procedure”, if anyone
> recalls how to do it.
> (Maybe it was a Jim Bounds testing trick, dictated over the phone (?)
> but i figured i’d try here before i bothered Jim, again!
> thanks everybody,
> Greg
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
If the sense wire opens, the output voltage will climb to the internal limit value - 18 Volts or so. This will Break Things. If the 12V 'on' wire
opens, the alternator will produce no output. The most common point of failure is the 40 Y/O plug which is plugged into the alternator, or is plugged
into the APC if you have one fitted. Tha APC adds a connection point, which has new connectors on one side of each of the original fittings. It
actually improves things, because it gets a clean surface into each connection. An intermittent connection will eventually fail the regulator if it's
left to switch on and off or between twelve and 18 volts.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
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