Home » Public Forums » GMCnet » [GMCnet] electrical short
| [GMCnet] electrical short [message #342216] |
Wed, 03 April 2019 09:15  |
Kathy and Fred Estabr
Messages: 55
Registered: May 2013
Karma: 0
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I have an electrical short that I can't find. I have gone through Bob
Hendrickson GMCES House Electrical and Rick Denney Electrical System Top
Down but without any success. I thought that the two electrical systems,
house and engine, were completely separate but I can't get the engine
system working without the house battery connected When it went down
both batteries went dead.I have a Progressive Dynamics converter but no
combiner. Any suggestions??.
Fred Estabrook
76 El
Florence AZ
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| Re: [GMCnet] electrical short [message #342218 is a reply to message #342216] |
Wed, 03 April 2019 09:29  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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If you are talking 12V systems, they are separate except at the isolator (if it fails shorted) or at the boost solenoid if it were to be stuck "on" or failed internally. All easy to diagnose with a cheap VOM.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] electrical short [message #342222 is a reply to message #342216] |
Wed, 03 April 2019 10:17 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Well, If you were a little closer, I would come help you. Odds are that you have a PO inflicted wiring error somewhere I doubt that you have an isolator problem.
Has this ever worked correctly for you in the past?
Have you made any wrong changes recently?
You are going to need a voltmeter or at least a test light. You are correct in that the engine and house systems are two separate batteries etc.
I guess where we might start is to charge up both batteries and then disconnect the house battery temporarily. Also unplug the 120vac so the converter is not running.
Will the engine crank?
If no, will the headlights work?
Will an over head light in the house section work?
Answer those questions and we will proceed from there.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] electrical short [message #342227 is a reply to message #342216] |
Wed, 03 April 2019 14:01 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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I step in here for just a moment and then let it all go back to KenB.
My first suggestion is that you disconnect both batteries and charge both. While they are charging, using the good wiring diagrams, disconnect the known cross connections at the isolator and boost contactor (solenoid/relay). This SHOULD isolate the systems. (After 40+ years of POs messing with things, there is no telling what has been done.... )
As you have the good diagrams, you have a good start. The KenB on your team, you already have a big head start. (I bet that if he sat down to draw diagrams of all three systems, he would probably make ONE mistake.) If you have questions, ask them.
You didn't mention what you own for test equipment. Please list that with your next response.
I will leave you with KenB now. I know that we will hear what happened.
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: [GMCnet] electrical short [message #342248 is a reply to message #342227] |
Thu, 04 April 2019 04:55 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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DO not run away Matt. I am up to my ears doing taxes. I am in my 3rd day and have not been out of the house on days. I have a real mess here. I am just about done with the feds and not the Indiana program will not run.
Where I was headed with this guy was to see if they are really shorted together. I was thinking to remove the house power sources and see what it did on just the engine battery. If everything worked on the engine battery, then I was going to have him disconnect at the isolator and at the boost solenoid. There is always more than one way to approach a problem. Your input and help is always appreciated.
I have been watching been about your a-frame problem. I could not think of anything I could do to help. If there is anything you need from me, just let me know.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] electrical short [message #342254 is a reply to message #342253] |
Thu, 04 April 2019 12:54 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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if you have an old school battery charger with an amp meter than can help determine how much of a short you have. Does it draw 1 amp? 10 amps? 0.1 amps? Just unhook the batteries and power the coach with the charger.
the fact that the engine is running off the house batt is suspicious, do you have the battery selector set right? Or is it set to combine and your engine circuit is dead....
________________________________
From: Gmclist on behalf of Matt Colie via Gmclist
Sent: Thursday, April 4, 2019 11:55 AM
To: gmclist@list.gmcnet.org
Cc: Matt Colie
Subject: Re: [GMCnet] electrical short
Kathy and Fred Estabr wrote on Thu, 04 April 2019 10:45
> Thank you Matt. For some reason my GMCNET emails were going to trash so I didn't see them until now. I am trying to correct this.
> I have a good wiring diagram and a multifunction tester and will follow your suggestions. I will try to contact KenB
> Thanks again
> Fred Estabrook
> 76El
> Florence AZ
KenB is very busy right now with taxes.
But, for a first test, when charged, hook up one bank at a time and see what works and what does not. You should have whichever bank up to about 12V
before you start. If it is less, you may get some wrong answers.
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
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] electrical short [message #342255 is a reply to message #342254] |
Thu, 04 April 2019 14:21 |
GatsbysCruise
Messages: 261
Registered: January 2017
Location: Waukegan, Illinois
Karma: 3
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Hi, I'm late to the game but let's see whats what.
Yes, the engine battery circuit and the coach battery circuit are completely separate.
The only ties I can think of is the battery tie solenoid and the combiner.
First, unless there is a malfuction of either the solenoid or combiner, the coach battery would not
be able to run the coach.
Second, the first thing that came to mind was a problem with the engine battery, but your solenoid would
have to be either closed, shorted or some cables touching somewhere. Keep in mind, if you had a connector
touching, there are some big amps going through to start the engine, there would have to be sparks and
or heat.
I think it would be difficult to think the combiner could malfunction to the point that it would allow
the coach battery to back feed, this brings me back to the solenoid.
DID YOU OR A SHOP DO ANY RECENT WORK ON YOUR COACH ELECTRICAL OR ANYTHING?????
If you connect the battery to the engine cables, what happens?
did you check your ground connections?
If you use a meter to check voltage on the UNCONNECTED coach battery at this time, is it alive or dead?
Do you get full voltage readings pos to chassis ground?
You may have to disconnect the cable to the combiner and the battery tie solenoid to proceed.
Did you have a fire or hot wires recently? Alternator malfunction???
I hate to ask but is the fuseable link good??? it is hard to find but should be noted on a schematic.
If you connect the battery to the engine cables, no battery on the coach cables and there is no
power, check that the coach pos cable is dead. if the coach battery pos cable is reading 12v dc,
disconnect the wire from the solenoid. Check for voltage again on the Coach Battery pos cable.
It should be dead, no voltage.
again, if the engine battery is in place and connected and the engine won't start, check the negative
cable both at the battery and where it bolts to the frame/engine
I think that is pretty basic at this point....
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO - UBUNTU VOYAGER - Berzin Auto Center
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| Re: [GMCnet] electrical short [message #342285 is a reply to message #342253] |
Thu, 04 April 2019 19:51 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Matt Colie wrote on Thu, 04 April 2019 11:55Kathy and Fred Estabr wrote on Thu, 04 April 2019 10:45Thank you Matt. For some reason my GMCNET emails were going to trash so I didn't see them until now. I am trying to correct this.
I have a good wiring diagram and a multifunction tester and will follow your suggestions. I will try to contact KenB
Thanks again
Fred Estabrook
76El
Florence AZ
KenB is very busy right now with taxes.
But, for a first test, when charged, hook up one bank at a time and see what works and what does not. You should have whichever bank up to about 12V before you start. If it is less, you may get some wrong answers.
Matt
Make sure you also turn off the converter or unplug the 120vac to the coach when doing the tests. We do not want another 12vdc source on when doing these tests.
Yes Matt I was up until 4 AM doing Federal taxes. I need to finish them and then start the state. What a pain on top of my sinus headaches. Good Luck on getting your coach going.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] electrical short [message #342398 is a reply to message #342285] |
Tue, 09 April 2019 09:44 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Hire a bookkeeper and an accountant an go to bed on time
Sully
Bellevue wa
On Thu, Apr 4, 2019 at 6:22 PM Ken Burton via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Matt Colie wrote on Thu, 04 April 2019 11:55
>> Kathy and Fred Estabr wrote on Thu, 04 April 2019 10:45
>>> Thank you Matt. For some reason my GMCNET emails were going to trash
> so I didn't see them until now. I am trying to correct this.
>>> I have a good wiring diagram and a multifunction tester and will
> follow your suggestions. I will try to contact KenB
>>> Thanks again
>>> Fred Estabrook
>>> 76El
>>> Florence AZ
>>
>> KenB is very busy right now with taxes.
>> But, for a first test, when charged, hook up one bank at a time and see
> what works and what does not. You should have whichever bank up to about
>> 12V before you start. If it is less, you may get some wrong answers.
>>
>> Matt
>
> Make sure you also turn off the converter or unplug the 120vac to the
> coach when doing the tests. We do not want another 12vdc source on when
> doing
> these tests.
>
> Yes Matt I was up until 4 AM doing Federal taxes. I need to finish them
> and then start the state. What a pain on top of my sinus headaches. Good
> Luck on getting your coach going.
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] electrical short [message #342525 is a reply to message #342216] |
Mon, 15 April 2019 07:54 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Ken, I have the past president of the State CPA Ass'n doing mine, since she's also the Obedience trainer for the Borders. Inexpensive and effective.
Now for GMCs, it's essential to isolate the two 12V electrical systems. Which as someone said includes turning off the 12V power supply. Then finding out where they are cross connected and correcting the cross connect. If that doesn't correct the trouble, it does allow finding it.
--johnny
Foolish Carriage, 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
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