Home » Public Forums » GMCnet » Electrical detective?
| Electrical detective? [message #212256] |
Tue, 25 June 2013 21:31  |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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I like to solve puzzles, real world puzzles but I'm looking for someone with more electrical ability than me can help out.
I've had lots of corrosion issues but this is something different. The 12 volt fuse panel but after cleaning, fuse number 8 blows intently. It is labeled floor lighting but my floor lighting is working. It could be a swap of wires but no matter. That circuit blows fuses. A continuity test says that leg is not shorted to ground but still blows fuses.
More evidence, no porch light, no power at the switch. No lights in the bathroom. John L. recently suggested a bad ground in the overhead light but I haven't been able to check yet. All light fixtures are upgraded recently. I just bought this a month ago and is otherwise, a cream puff. Shows lots of evidence of pride of ownership . . . like most of us.
I'm sure there is more than one issue. Multiple problems are harder to diagnose but I'm sure one of you guys have had a similar problem or are just smarter than me. OK, no jokes. One more piece of info. I've owned a 1975 Palm Beach and a 1976 Palm Beach but this 1974 has a moulded roof panel in the hall between the bathroom and the closet that I have never seen before. Is this factory? It does not look too hard to drop but I'm waiting for the next day off Friday. Another clue, installed with square drive screws, although they may be replacements.
OK, you electrical detectives and GMC know it alls (in a good way), what is your prognosis?
1974 Palm Beach
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| Re: Electrical detective? [message #212258 is a reply to message #212256] |
Tue, 25 June 2013 21:37  |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Any rodent damage? My '73 aisle lights had he insulation chewed off/ shorted under the sink base cabinet. There was a nest above he hall ceiling panel, evidently the insulation there was not sprayed on, but similar to the blanket insulation in the rear and makes excellent fluff.
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
[Updated on: Tue, 25 June 2013 21:38] Report message to a moderator |
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| Re: Electrical detective? [message #212269 is a reply to message #212256] |
Tue, 25 June 2013 22:50 |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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I know I can always run new wires but I want try and solve the issue, kind of like a detective that wants to wrap up the case. Why is there no power? Why does the fuse blow? I don't always or can't always fix it, but dang it! I want to understand it.
1974 Palm Beach
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| Re: [GMCnet] Electrical detective? [message #212290 is a reply to message #212256] |
Wed, 26 June 2013 07:42 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Just like you eat an elephant - one bite at a time. To save some money, clip a 12V light bulb across the fuseholder. As long as the short exists, it will light. Save the cost of fuses. Is it lit? Disconnect the wire to the cold (load) side of the holder. Still lit? Bad fuse holder (It happens, but rarely). No light? Reconnect and follow the wire. Keep this up till something makes the light go out. That something contains a load greater than the fuse reating. Remember, 12 volts >can< arc across a very small space. Again it's rare but happens... usually whern a wire is pnched.
--johnny
'76 23' transmode norris
'76 palm beach
________________________________
From: Lance <lance@vonprum.com>
To: gmclist@temp.gmcnet.org
Sent: Tuesday, June 25, 2013 10:31 PM
Subject: [GMCnet] Electrical detective?
I like to solve puzzles, real world puzzles but I'm looking for someone with more electrical ability than me can help out.
I've had lots of corrosion issues but this is something different. The 12 volt fuse panel but after cleaning, fuse number 8 blows intently. It is labeled floor lighting but my floor lighting is working. It could be a swap of wires but no matter. That circuit blows fuses. A continuity test says that leg is not shorted to ground but still blows fuses.
More evidence, no porch light, no power at the switch. No lights in the bathroom. John L. recently suggested a bad ground in the overhead light but I haven't been able to check yet. All light fixtures are upgraded recently. I just bought this a month ago and is otherwise, a cream puff. Shows lots of evidence of pride of ownership . . . like most of us.
I'm sure there is more than one issue. Multiple problems are harder to diagnose but I'm sure one of you guys have had a similar problem or are just smarter than me. OK, no jokes. One more piece of info. I've owned a 1975 Palm Beach and a 1976 Palm Beach but this 1974 has a moulded roof panel in the hall between the bathroom and the closet that I have never seen before. Is this factory? It does not look too hard to drop but I'm waiting for the next day off Friday. Another clue, installed with square drive screws, although they may be replacements.
OK, you electrical detectives and GMC know it alls (in a good way), what is your prognosis?
--
1976 Palm Beach
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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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| Re: Electrical detective? [message #212299 is a reply to message #212256] |
Wed, 26 June 2013 08:39 |
Galen
Messages: 146
Registered: November 2011
Location: New Virginia, IA
Karma: 0
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I would start by removing the bulbs from the non working circuits, and measure resistance between the load side of the fuse holder and the bulb sockets, as well as between each point and ground. Verify the operation of the switches. If you are lucky and have a dead short, the lead with the smallest resistance value to ground is probably the one with the fault, or at least physically closest, and if your meter is accurate enough, you could convert the minimal resistance value to a maximum foot distance to know how far you might need to go.
Another possibility is that some PO, when they rewired, bridged some circuits together, and/or perhaps changed bulbs to lower resistance/higher wattage bulbs. This could cause you to draw too much current for the existing fuse. This is assuming the fuse blows when the switches are on and not off. I'd be verifying all 12 volt devices to see what is or is not operational, even things you might not know exist. Cooling fans for fridge coils for example, or a macerator circuit that isn't hooked up. Look around for wires everywhere.
I don't know how a bad ground could cause a fuse to blow. Bad grounds, as I call them, increase the resistance in a circuit, either because they are corroded or loosely connected, unless somehow the fixture was shorting to the source, so maybe that's just a terminology thing. I'd call that a short, because that fault is bypassing the load.
Not knowing how your fuse holders are wired, verify that you have a continuous bus of 12 volt and that the source side of this one holder isn't coming from some other circuit. If it is, the fault could be upstream.
Good luck.
Galen Briggs
New Virginia, Iowa
1978 Palm Beach
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| Re: Electrical detective? [message #212312 is a reply to message #212256] |
Wed, 26 June 2013 09:57 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| lance wrote on Tue, 25 June 2013 19:31 |
I like to solve puzzles, real world puzzles but I'm looking for someone with more electrical ability than me can help out.
I've had lots of corrosion issues but this is something different. The 12 volt fuse panel but after cleaning, fuse number 8 blows intently. It is labeled floor lighting but my floor lighting is working. It could be a swap of wires but no matter. That circuit blows fuses. A continuity test says that leg is not shorted to ground but still blows fuses. ...
... OK, you electrical detectives and GMC know it alls (in a good way), what is your prognosis?
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Lance,
You have been given good advice. The "trick" with the light across the (removed) fuse holder is a good one.
But another possible "PO induced" electrical problem are screws that happen to be drilled into the wires. It happens when installing things like awnings, cabinets and the like.
Sometimes, without gutting your coach  , it would be almost impossible to find the exact cause. But if you find a section of wire grounded out, just run another wire around it and be done.
Yes, the panel on the ceiling outside the bath is an OEM "feature" of a 1973/1974 coach.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: Electrical detective? [message #212433 is a reply to message #212256] |
Wed, 26 June 2013 22:51 |
Galen
Messages: 146
Registered: November 2011
Location: New Virginia, IA
Karma: 0
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Mike makes a good point. I tried to fix a coworker's fifth wheel one time. He had previously had a friend fix a loose panel on it for him. Some time after, he would trip the GFI breaker every time he plugged in. He brought it too work one day (where I have a lot of specialized test equipment) and I was able to electrically find the ground fault so many feet out, and trace it through the interior walls. I found where his neighbor had "fixed" his loose panel with a drywall screw and some silicon. The screw didn't initially cause a problem, but must have been rubbing and shorted over time. Fortunately it was the last outlet in loop, so we just disconnected that feed from the next upstream outlet and his problem went away. He didn't want to tear into his wallboard walls to repair it correctly, and I don't blame him. The GMC seems a little easier to fish.
Galen Briggs
New Virginia, Iowa
1978 Palm Beach
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| Re: Electrical detective? [message #212673 is a reply to message #212256] |
Fri, 28 June 2013 19:04 |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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Senior Member |
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You guys are the best. I will spend tomorrow troubleshooting with the light bulb across the fuse socket suggestion and report back. I highly suspect that my issue is behind the overhead panel in the hallway. I'll drop it tomorrow and begin wiggling wires while I watch the F1 race at Silverstone. Updates to follow. Continuing input is welcome.
1974 Palm Beach
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| Re: Electrical detective? [message #212820 is a reply to message #212673] |
Sun, 30 June 2013 09:00 |
lance
Messages: 190
Registered: December 2004
Location: Vancouver, WA
Karma: 0
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Senior Member |
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I found it! I dropped the center ceiling panel but found nothing so decided to run a new wire to power the bathroom lights. Below the left light switch in the bathroom is a water pump switch. I had to pull this out to get a good understanding and look at what wiring I could because this area had been messed with when the newer lights were installed. The PO also installed a push button switch wired to turn all the lights on with one switch. He used a wire tap and a 20 gauge wire the feed power to the switches. The 20 gauge wire was too small and melted and shorted with a ground wire on the push button. I eliminated the broken push button switch and put the wiring back to factory and all is well except I have a wire run that I now don't need, but I also repaired the water pump circuit. I still haven't fixed the porch light. No 12v at the switch and no more PO wiring to clean up.
1974 Palm Beach
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