| Help with a simple electrical question [message #114574] |
Tue, 08 February 2011 17:14  |
pbrownsd
Messages: 56
Registered: December 2010
Location: Hayden,ID
Karma: 0
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Ok- still trying to wrap my brain around the GMC's electrical systems. I'm having trouble keeping the batteries charged. I have to jump start it if it sits for more than a day. I just recently purchased it so I don't know if the batteries themselves are shot, but planning on replacing them soon. However I want to know that the rest of the system is ok before ruining the new batteries.
The PO put a alligator clip jumper cable from the isolator to the battery boost. It won't start without it in place. So does this mean its using the house battery to start? Once running, the volt meter says 13.8-14.1 so I think the alternator is fine. Do I need to just replace batteries? Isolator? boost thingy?
Here's a pic of the jumper wire:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37674&title=img-0976&cat=5692
Pete I love my GMC Brown
1976 Glenbrook
Hayden, ID
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| Re: [GMCnet] Help with a simple electrical question [message #114578 is a reply to message #114574] |
Tue, 08 February 2011 17:34  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Looks like the jumper just turns on the boost relay ( I guess the switch on
the dash must not work.)
You should never need the boost relay. Here is some information , that just
says, you need to wire the starter directly to the battery.
http://goo.gl/Gqo1m
If your battery is good, then you have bad connections to the engine. A
ground to the frame is usually the problem.
BATTERY
If this testing is not your thing, have your battery tested.
and if it is good do this
http://goo.gl/j1VOC
so the final answer is plus wire from the battery to the starter. negative
wire from the engine to the battery
good luck
gene
On Tue, Feb 8, 2011 at 3:14 PM, Pete <pbrownsd@yahoo.com> wrote:
>
>
> Ok- still trying to wrap my brain around the GMC's electrical systems. I'm
> having trouble keeping the batteries charged. I have to jump start it if it
> sits for more than a day. I just recently purchased it so I don't know if
> the batteries themselves are shot, but planning on replacing them soon.
> However I want to know that the rest of the system is ok before ruining the
> new batteries.
>
> The PO put a alligator clip jumper cable from the isolator to the battery
> boost. It won't start without it in place. So does this mean its using the
> house battery to start? Once running, the volt meter says 13.8-14.1 so I
> think the alternator is fine. Do I need to just replace batteries? Isolator?
> boost thingy?
>
> Here's a pic of the jumper wire:
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=37674&title=img-0976&cat=5692
>
> Pete I love my GMC Brown
>
>
> --
> 1976 Glenbrook
>
> Hayden, ID
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: Help with a simple electrical question [message #114580 is a reply to message #114574] |
Tue, 08 February 2011 17:42 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Senior Member |
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My guess is that the boost switch is trying to get it's power from a dead battery's circuit, and when the jumper wire is in place, it draws its power from the other battery bank.
A voltmeter would let you know what the resting voltage of the two battery banks (house and engine) is, but I would also agree that it's tough to diagnose the systems with a bad battery.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: Help with a simple electrical question [message #114584 is a reply to message #114580] |
Tue, 08 February 2011 18:50 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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Senior Member |
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That battery boost solenoid will run the battery down by being a constant drain. I suspect that the start battery is bad and you are starting on the house battery. When the battery is charged try disconnecting the jumper and see if it will start a couple of days later with or without the jumper. If it starts with the jumper, then your engine battery is not keeping a charge for some reason. Of course that reason could be a bad battery connection, etc...........
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: [GMCnet] Help with a simple electrical question [message #114586 is a reply to message #114577] |
Tue, 08 February 2011 18:59 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
You could buy one of these:
http://www.harborfreight.com/100-amp-6-volt-12-volt-battery-load-tester-9063
6.html
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of KRDietz
Sent: Wednesday, February 09, 2011 10:31 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Help with a simple electrical question
Pull the batteries out, charge them up and then take them someplace that
can load them down and check their condition. All but the smallest of
towns have a local battery shop. No idea if Hayden, ID is that small. :^)
RV batteries usually have a pretty short life. I've found my
Progressive Dynamics converter keeps them alive for a lot longer. Got 7
years out of the last set. Trying to figure out the electrical system
with bad batteries is kind of futile.
Kelvin
'73 23' in Eugene, OR
>
> Ok- still trying to wrap my brain around the GMC's electrical systems.
I'm having trouble keeping the batteries charged. I have to jump start it
if it sits for more than a day. I just recently purchased it so I don't
know if the batteries themselves are shot, but planning on replacing them
soon. However I want to know that the rest of the system is ok before
ruining the new batteries.
>
> The PO put a alligator clip jumper cable from the isolator to the battery
boost. It won't start without it in place. So does this mean its using the
house battery to start? Once running, the volt meter says 13.8-14.1 so I
think the alternator is fine. Do I need to just replace batteries? Isolator?
boost thingy?
>
> Here's a pic of the jumper wire:
>
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37674&title=img-0976&c
at=5692
>
> Pete I love my GMC Brown
>
>
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GMCnet mailing list
Unsubscribe or Change List Options:
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_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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