Alternator issues 1976 Palm Beach

> 63 amp or 100 amp?

I have found that most of the available are the 100 Amp, Some were also 80.
Just get what you can that works.

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
O.K. Samuel, let's go back one more step to very basic electricity.
Let's verify that you have your meter set correctly. You should be on
DC VOLTS. If your meter has a 20 volt scale, that should work. If
it doesn't, and has a 200 volt scale or is auto ranging, use that.
Place the meter lead that is marked "positive" ( should be the red
lead) on the positive battery post, and the lead marked "negative" (should
be black) on the battery negative post.
If your battery is good, and has a full charge, the meter should read
12.5 volts DC or better. But, no higher than 13.2 volts DC. If it does,
with the engine NOT RUNNING, something is wrong with your meter settings,
or the meter itself is not working right. So do that, and let us know that
we are singing off the same music.
Jim Hupy
Salem, Oregon

On Sat, Sep 21, 2019, 3:31 PM Matt Colie via Gmclist <

> > 63 amp or 100 amp?
>
> I have found that most of the available are the 100 Amp, Some were also
> 80.
> Just get what you can that works.
>
> Matt
>
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
James,

Digital meter has 20v & 200v setting. Checked all on both settings and get the collosing:

Battery showing 12.5 volts with ignition off.

Engine running- alternator is showing 34 volts output on red wire coming from back of alternator to center post of isolator box.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)
 
Don't run it like that. Remove the alternator and have it tested. Check the
wire harness that you have on your coach, particularly on the part of the
harness that plugs into the alternator.
Jim Hupy

On Sat, Sep 21, 2019, 5:10 PM Samuel Ferguson via Gmclist <

> James,
>
> Digital meter has 20v & 200v setting. Checked all on both settings and get
> the collosing:
>
> Battery showing 12.5 volts with ignition off.
>
> Engine running- alternator is showing 34 volts output on red wire coming
> from back of alternator to center post of isolator box.
>
> Samuel
> --
> Samuel Ferguson
> Pittsfield, Illinois
> (West Central Illinois)
> 1976 GMC Palm Beach (A newbie who will not allow this thing to kick my
> butt!!)
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Jim & Steve,

It sounds to me like the alternator may be OK, but the isolator's got a bad
chassis battery diode, preventing the runaway alternator from getting
feedback voltage from the chassis battery. Being on email only, I can't
see any of the photos to help follow the narrative. At any rate, the
alternator, even without feedback on the sense line should be internally
limited to 18 VDC (but they aren't all!).

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Sat, Sep 21, 2019 at 3:52 PM James Hupy via Gmclist <

> You either have your meter on the wrong scale, you have a faulty meter, OR,
> your alternator is running away, ( no regulation) it should be in the range
> of 14.5 volts. If it is not your meter setting, then your alternator is
> bad. Fix that before you do anything else.
> Jim Hupy
> Salem, Oregon
>
> On Sat, Sep 21, 2019, 12:45 PM Samuel Ferguson via Gmclist <

>
> > Yes, I have the conductor from alternator - When engine running, I am
> > showing 34. to 36.9 volts from alternator to center lug of isolator.
> >
> > The same voltage showing to right side of isolator.
> >
> > No reading showing on left side of isolator.
> >
> > Samuel
> >
> > --
> > Samuel Ferguson
> > Pittsfield, Illinois
> > (West Central Illinois)
> > 1976 GMC Palm Beach (A newbie who will not allow this thing to kick my
> > butt!!)
> >
> > _______________________________________________
> > 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
>
 
Sir, does your alternator have a small plug above the big red one with 2 small wires in it?

> Don't run it like that. Remove the alternator and have it tested. Check the
> wire harness that you have on your coach, particularly on the part of the
> harness that plugs into the alternator.
> Jim Hupy
>
> On Sat, Sep 21, 2019, 5:10 PM Samuel Ferguson via Gmclist <

>
> > James,
> >
> > Digital meter has 20v & 200v setting. Checked all on both settings and get
> > the collosing:
> >
> > Battery showing 12.5 volts with ignition off.
> >
> > Engine running- alternator is showing 34 volts output on red wire coming
> > from back of alternator to center post of isolator box.
> >
> > Samuel
> > --
> > Samuel Ferguson
> > Pittsfield, Illinois
> > (West Central Illinois)
> > 1976 GMC Palm Beach (A newbie who will not allow this thing to kick my
> > butt!!)
> >
> > _______________________________________________
> > 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

--
C. Boyd
76 Crestmont
East Tennessee
 
The wire closest to the big red wire is #1 the wire furthest away from big red wire is #2 and should have 12 volts on it with key on. Does it? What
is #1 voltage?

Ken we got no pics on Forum either.

> Yes Sir. There is a plug with 2 wires. White and brown.
>
> Samuel

--
C. Boyd
76 Crestmont
East Tennessee
 
12 volts on #2 wire with key on. #1 wire had voltage on it so, but it had a lower voltage than #2 wire.

I cant figure out how to upload pics on here. I found a photo compressing program, but still trying to figure it out. Sorry

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)
 
Well Col Ken and everybody else knows a lot more than I do about electrics and GMCs. But the book says you have an internal short in the alternator
and needs to be checked.

I haven't figured out how to resize the pics either. I'm using an IPad and it is different..

> 12 volts on #2 wire with key on. #1 wire had voltage on it so, but it had a lower voltage than #2 wire.
>
> I cant figure out how to upload pics on here. I found a photo compressing program, but still trying to figure it out. Sorry
>
> Samuel

--
C. Boyd
76 Crestmont
East Tennessee
 
What is the engine battery voltage with and without the engine running?

RonC

> > James,
> >
> > Digital meter has 20v & 200v setting. Checked all on both settings
> and get
> > the collosing:
> >
> > Battery showing 12.5 volts with ignition off.
> >
> > Engine running- alternator is showing 34 volts output on red wire
> coming
> > from back of alternator to center post of isolator box.
> >
> > Samuel
> > --
> > Samuel Ferguson
> > Pittsfield, Illinois
> > (West Central Illinois)
> > 1976 GMC Palm Beach (A newbie who will not allow this thing to
> kick my
> > butt!!)
> >
> > _______________________________________________
> > 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
>

Ron & Linda Clark
North Plains, ORYGUN
1978 Eleganza II
 
Ken and all, earlier He said battery acc fuse was blowing? And didn't you say it was the circuit going to to the boost switch? In looking at the
X7425 73-74 (6y-19) manual cause it has more stuff about alternator circuit, it shows a drawn picture of the 2 wires going to small plug. It shows a
straight 12 volts to #2 and a wire coming off the ignition switch going thru a resistor going to #1 and is marked "acc"?? Is this the same circuit
that is blowing the fuse? Or would the alternator overcharging blow the fuse or could the resistor wire be causing the overcharging even tho it
checks with a VOM as it should?

> Well Col Ken and everybody else knows a lot more than I do about electrics and GMCs. But the book says you have an internal short in the
> alternator and needs to be checked.
>
> I haven't figured out how to resize the pics either. I'm using an IPad and it is different..
>
>
>
>
>

> > 12 volts on #2 wire with key on. #1 wire had voltage on it so, but it had a lower voltage than #2 wire.
> >
> > I cant figure out how to upload pics on here. I found a photo compressing program, but still trying to figure it out. Sorry
> >
> > Samuel

--
C. Boyd
76 Crestmont
East Tennessee
 
I think Ken H. is correct. that could result in overheating a wire, thus
causing a fire. check the diodes in the isolator, and replace it if
needed. Should be about 0.7 volts between center
bolt and the outside ones. Somebody makes a gizmo that connects in there
somewhere that prevents that, but I don't remember details. If the
voltage is greater than about 0.7 volts, replace the isolator.
www.appliedgmc.com � prod.itml � icOid

Ronc

On Sat, 21 Sep 2019 20:29:08 -0400 Ken Henderson via Gmclist

> Jim & Steve,
>
> It sounds to me like the alternator may be OK, but the isolator's
> got a bad
> chassis battery diode, preventing the runaway alternator from
> getting
> feedback voltage from the chassis battery. Being on email only, I
> can't
> see any of the photos to help follow the narrative. At any rate,
> the
> alternator, even without feedback on the sense line should be
> internally
> limited to 18 VDC (but they aren't all!).
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> www.gmcwipersetc.com
>
>
> On Sat, Sep 21, 2019 at 3:52 PM James Hupy via Gmclist <

>
> > You either have your meter on the wrong scale, you have a faulty
> meter, OR,
> > your alternator is running away, ( no regulation) it should be in
> the range
> > of 14.5 volts. If it is not your meter setting, then your
> alternator is
> > bad. Fix that before you do anything else.
> > Jim Hupy
> > Salem, Oregon
> >
> > On Sat, Sep 21, 2019, 12:45 PM Samuel Ferguson via Gmclist <

> >
> > > Yes, I have the conductor from alternator - When engine running,
> I am
> > > showing 34. to 36.9 volts from alternator to center lug of
> isolator.
> > >
> > > The same voltage showing to right side of isolator.
> > >
> > > No reading showing on left side of isolator.
> > >
> > > Samuel
> > >
> > > --
> > > Samuel Ferguson
> > > Pittsfield, Illinois
> > > (West Central Illinois)
> > > 1976 GMC Palm Beach (A newbie who will not allow this thing to
> kick my
> > > butt!!)
> > >
> > > _______________________________________________
> > > 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
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

Ron & Linda Clark
North Plains, ORYGUN
1978 Eleganza II
 
Engine battery should be about 14 volts with the engine running. Same
voltage running/not running sounds like open isolator diode.

RonC

On Sat, 21 Sep 2019 20:01:43 -0600 Samuel Ferguson via Gmclist

> Engine battery voltage engine running/not running is 12.5 volts
>
> Samuel
> --
> Samuel Ferguson
> Pittsfield, Illinois
> (West Central Illinois)
> 1976 GMC Palm Beach (A newbie who will not allow this thing to kick
> my butt!!)
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

Ron & Linda Clark
North Plains, ORYGUN
1978 Eleganza II
 
You stated this is your 3rd alternator? Is there any chance you are getting the wrong one? 76 Toronado is what we are looking for. I do think as
Ken that the isolator is bad. I was just wondering is there any chance parts store is giving you a one wire alternator and if it would cause this.
The book says this could be caused by a brush holder grounding or a washer in the wrong place in the alternator. Maybe a chance they have a bad batch
with same rebuilder doing the same thing to a bunch of them?? I just seem Im way over my pay grade on this one.
https://www.gmcmi.com/wp-content/uploads/2014/05/X7425_73-74-maint-manual.pdf

> The aux battery/radio fuse (10 amp fuse) is blowing.
>
> Samuel

--
C. Boyd
76 Crestmont
East Tennessee
 
Maybe PO has replaced radio and tried to splice radio light to grey wire going to dash lights which I think could be a ground..

> The aux battery/radio fuse (10 amp fuse) is blowing.
>
> Samuel

--
C. Boyd
76 Crestmont
East Tennessee
 
Yes Sir, 3rd alternator. The 1st one I bought, that's how they looked up what alternator would be. 76 Olds Tornado 7.5L.

I have heard the remanufactured alternators are like flipping a coin as to if they will work and/or last.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)
 
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