| House Battery connection clean up [message #356891] |
Fri, 17 July 2020 12:24  |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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So after getting all the front battery connections cleaned up I went back to the house battery connections to clean those up and got a spark from the first connection I tried to unbolt. This was with no house battery and the coach unplugged. Do I remember correctly that the isolator is suppose to separate the starter battery from the house battery? The starter battery is the only thing ghat has current to spark like that. Has my isolator failed?
Thanks,
TG
76 Eleganza 2
KCMO
Tom Geiger
76 Eleganza II
KCMO
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| Re: [GMCnet] House Battery connection clean up [message #356895 is a reply to message #356891] |
Fri, 17 July 2020 12:37  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Tom,
You're absolutely correct that the isolator should prevent the
chassis/starter battery from feeding the house battery. But it's not
likely that the voltage you saw at the house battery terminal came from the
chassis battery because the common failure mode of the isolator is to
become OPEN, not shorted. It's much more likely that some wire has been
misconnected, less likely that the solenoid relay for the boost function
(below the isolator on the firewall) has "welded" closed, and somewhat more
likely that the dash Boost switch is ON ('tho' your '76 Eleganza should
have a momentary switch there).
Use a trouble light to easily track down the problem.
Ken H.
On Fri, Jul 17, 2020 at 1:25 PM tom geiger via Gmclist <
gmclist@list.gmcnet.org> wrote:
> So after getting all the front battery connections cleaned up I went back
> to the house battery connections to clean those up and got a spark from the
> first connection I tried to unbolt. This was with no house battery and the
> coach unplugged. Do I remember correctly that the isolator is suppose to
> separate the starter battery from the house battery? The starter battery
> is the only thing ghat has current to spark like that. Has my isolator
> failed?
>
> Thanks,
> TG
> 76 Eleganza 2
> KCMO
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: House Battery connection clean up [message #356896 is a reply to message #356891] |
Fri, 17 July 2020 13:18 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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I was just trying to take apart the cables and wires off one of the relays back there to clean up the connectors with a brass brush. Just wasn’t expecting sparks back there when everything is disconnected except for the starter battery, which I thought was separated from the wiring back at the house.
TG
Tom Geiger
76 Eleganza II
KCMO
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| Re: [GMCnet] House Battery connection clean up [message #356900 is a reply to message #356896] |
Fri, 17 July 2020 15:27 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Whoa now! I hadn't read this "...back there..." statement before my
previous email. If you were working in the rear of the coach, you were
working with connections to the house battery, which I understood to still
be connected. I, too, am confused.
Ken H.
On Fri, Jul 17, 2020 at 2:19 PM tom geiger via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I was just trying to take apart the cables and wires off one of the relays
> back there to clean up the connectors with a brass brush. Just wasn’t
> expecting sparks back there when everything is disconnected except for the
> starter battery, which I thought was separated from the wiring back at the
> house.
>
> TG
>
> _______________________________________________
> 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
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: House Battery connection clean up [message #356911 is a reply to message #356891] |
Fri, 17 July 2020 20:27 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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No solar panel . I’ve been searching on the web for a battery cable, starter and house battery cable hookup diagram for up front. Something that would show how the battery cables are suppose to be arranged. Have not found anything as of yet. The electrical diagrams I have out of my manuals don’t show the isolator in the diagram, so I’m not seeIng a clear correlation with them.
I’ll try to describe my arrangement to verify I have them connected correctly. The positive battery cable goes up to the positive juntion post on the aluminum plate. I have a short positive cable going from that junction down to the silinoid right side post. On that right side post I also have another battery cable that goes down to the starter. The left side solenoid post has the house battery cable connected to it. The last negative battery cable goes down and grounds on the engine block. Thats the main battery cable arrangement I have.
Thanks,
TG
Tom Geiger
76 Eleganza II
KCMO
[Updated on: Sat, 18 July 2020 05:42] Report message to a moderator |
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| Re: House Battery connection clean up [message #356915 is a reply to message #356911] |
Sat, 18 July 2020 02:02 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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tgeiger wrote on Fri, 17 July 2020 20:27No solar panel . I’ve been searching on the web for a battery cable, starter and house battery cable hookup diagram for up front. Something that would show how the battery cables are suppose to be arranged. Have not found anything as of yet. The electrical diagrams I have out of my manuals don’t show the isolator in the diagram, so I’m not see a clear correlation with them.
I am looking at two different versions of the standard GMC wiring diagrams and the isolator is definitely there. It is labeled "Generator Output Diodes" Look down the left side of the diagram not too far from the top and you will see the words "Generator Output Diodes". The isolator outputs go to the boost relay called the "Auxiliary Battery Switch" and the "Battery Pickup Junction Block".
The other items you asked for are also shown on the diagram. If you do not have the GMC wiring diagram, download it from www.bdub.net or buy a huge one on paper from Ken Henderson. His son Alan prints them.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: House Battery connection clean up [message #356934 is a reply to message #356891] |
Sat, 18 July 2020 15:52 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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One more item I had forgotten anout was the internal living area lights worked even when the house battery was out so the starter battery is somehow feeding those circuits.
TG
Tom Geiger
76 Eleganza II
KCMO
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| Re: House Battery connection clean up [message #356936 is a reply to message #356891] |
Sat, 18 July 2020 16:40 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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So looking at the wiring diagram it shows starter, pos battery and a short pos jump #4 cables all going to the right post of the Starter relay which is mounted on the aluminum plate/fire wall by the isolator. The post length there seems to be too short to tie all 3 cables on it.
Tom Geiger
76 Eleganza II
KCMO
[Updated on: Sat, 18 July 2020 17:44] Report message to a moderator |
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| Re: House Battery connection clean up [message #356946 is a reply to message #356891] |
Sat, 18 July 2020 18:31 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Hard to tell being no where near the coach, but perhaps PO stacked all the cables on one side of the boost solenoid as a “temporary” fix for no house battery.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: House Battery connection clean up [message #356952 is a reply to message #356891] |
Sat, 18 July 2020 19:27 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Yes electrical is always fun to figure out. I think I’ll try to find the flat connectors instead of the thinker battery connectors you get when you get a battery cable.
Tom Geiger
76 Eleganza II
KCMO
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| Re: House Battery connection clean up [message #356967 is a reply to message #356891] |
Sun, 19 July 2020 09:05 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Ken, I’ll check the isolator and more like just replace it with new one. I do have a combiner around here in its package, never installed it. May be time to here.
TG
Tom Geiger
76 Eleganza II
KCMO
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| Re: House Battery connection clean up [message #356974 is a reply to message #356967] |
Sun, 19 July 2020 10:40 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Tom,
At this point you should be aware that with the house lights on the main engine battery, you are all set up for a "Totally Dead Coach" syndrome. It is important that this situation be corrected.
With the expertise you have on tap here (not to include yours truly), this should not be that difficult to get squared away.
Now, please do both us and you a favor. Create a sigfile. To do this go up to <Control Panel/Account Settings> then down to <Preferences> and click. There will be a box - Signature - in that box put something like:
Tom Geiger, 76 Eleganza 2, KCMO
We like to know who it is we are helping and be able to know you when we meet at a rally. The 76 Eleganza 2 is essential because not all coaches are/were the same and this save me having to go back to you lead post all the time. And KCMO is so if there is someone that can assist that is in striking range, he can contact you. (This last actually happens a lot here.)
Now, something read like you have wiring diagrams. If you don't we can fix that. I will add to the suggestion that you compare what is under the right hood and see if you can spot a mis-placed connection.
Hang in there this group has gotten more and bigger problems than this fixed.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: House Battery connection clean up [message #356984 is a reply to message #356891] |
Sun, 19 July 2020 13:46 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Thanks Matt, appreciate the help. As I mentioned before not real knowledgeable on electrical stuff but am doggedly stubborn in trying to fixing something thats not correct on it. This apparent current draw from the starter battery points to me on the isolator but did not consider the booster switch although its a 76 so booster switch springs back to the off position. The starter battery feeding the interior lights has been something I’ve notice this season.
TG
Tom Geiger
76 Eleganza II
KCMO
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