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09-06-2016, 07:38 AM
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#1
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Finding a short question
OK many of you will recognize that I have often posted information on electrical issues and may ask why is he now asking for help. While I understand the basics of electricity I do not know how Airstream assembles the trailer with respect to wire routing.
I have a short in the circuit that feeds the bedroom overhead light and the bathroom lights. While the schematic shows the circuit it does not show the points where lines break off. My question is do the feed the first fixture and use it as a junction box or have they bury connections I the ceiling, against housing codes and good sense?
I am going to wire a light bulb between the circuit breaker and the line at the breaker panel and use the short as ground. Working my way back from fixture to fixture watching to see when the light goes out to indicate the point just before the short. I hope they wired from fixture to fixture and the short appears in a fixture.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-06-2016, 07:46 AM
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#2
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3 Rivet Member
1973 31' Excella 500
Vicksburg
, Mississippi
Join Date: Jul 2016
Posts: 164
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Howie my 1973 had several junctions hidden in ceiling for the 12v system but the 120v used junction boxes only. It had those cheap press in outlets but no hidden splices.
Good luck!
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09-06-2016, 08:13 AM
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#3
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Should have mentioned my short is in a 12 volt circuit. The hidden splices you mention is what I feared.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-06-2016, 11:23 AM
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#4
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Rivet Master
1974 31' Sovereign
1979 23' Safari
Wayland
, New York
Join Date: Jan 2012
Posts: 1,632
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Quote:
Originally Posted by HowieE
OK many of you will recognize that I have often posted information on electrical issues and may ask why is he now asking for help. While I understand the basics of electricity I do not know how Airstream assembles the trailer with respect to wire routing.
I have a short in the circuit that feeds the bedroom overhead light and the bathroom lights. While the schematic shows the circuit it does not show the points where lines break off. My question is do the feed the first fixture and use it as a junction box or have they bury connections I the ceiling, against housing codes and good sense?
I am going to wire a light bulb between the circuit breaker and the line at the breaker panel and use the short as ground. Working my way back from fixture to fixture watching to see when the light goes out to indicate the point just before the short. I hope they wired from fixture to fixture and the short appears in a fixture.
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The circuits run along the ceiling from the fuse panel along to the last load. It will usually run front to back or back to front. Usually continues progress in one direction. So the circuit won't go from forward load to back load to forward load. Each load will have a splice that a wire comes from to feed each load. It sounds like you have a electric diagram that shows the loads on your bad circuit. Best bet is to investigate at the last working load on that circuit.
"I am going to wire a light bulb between the circuit breaker and the line at the breaker panel and use the short as ground. Working my way back from fixture to fixture watching to see when the light goes out to indicate the point just before the short. I hope they wired from fixture to fixture and the short appears in a fixture."
This is a bad way to search for a short. You're bypassing the circuit protection to excessive current draw and creating an electric and fire hazard. It's better to search using resistance. Pull the fuse. Connect a long wire that can reach all the loads to the output side of the circuits fuse block. Doesn't have to be heavy gauge it's just for continuity testing. Take the free end of the wire to the first load find the wire supplying the load. Use a multimeter to check the resistance between the test wire and load wire. If its zero you're good move on to the next load. When you find the spot where the resistance is not zero your short is between there and the previous good load. Check all the connections in those two loads.
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09-06-2016, 11:45 AM
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#5
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Rivet Master
2008 22' Safari
Spicewood (W of Austin)
, Texas
Join Date: Mar 2015
Posts: 2,950
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Why... didn't you know.../?? Each Airstream is wired in conduits and behind attractive panels so all wiring is easily reached behind "decorative panels".
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09-06-2016, 11:49 AM
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#6
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Quote:
Originally Posted by HiJoeSilver
"I am going to wire a light bulb between the circuit breaker and the line at the breaker panel and use the short as ground. Working my way back from fixture to fixture watching to see when the light goes out to indicate the point just before the short. I hope they wired from fixture to fixture and the short appears in a fixture."
This is a bad way to search for a short. You're bypassing the circuit protection to excessive current draw and creating an electric and fire hazard.
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Using the original circuit breaker to feed the test light bulb will maintain the protection. The problem is if Airstream did in fact splice branches to different fixtures in the ceiling I can not assume disconnecting within a given fixture will isolate the problem.
Using a meter would have to be very precise. The first reading would be the resistance of the new pigtail and the Airstream wire resistance. Each additional reading would increase by the addition of the additional Airstream wiring. Once I pass the short the resistance reading would not change as a result of the short. This would also require removing all bulbs on that circuit before starting.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-07-2016, 12:49 AM
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#7
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Stay CazuaL
2018 25' Flying Cloud
2014 19' Flying Cloud
Reseda
, California
Join Date: Aug 2014
Posts: 959
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Quote:
Originally Posted by Boxite
Why... didn't you know.../?? Each Airstream is wired in conduits and behind attractive panels so all wiring is easily reached behind "decorative panels".
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This video proves, who needs a fancy WD, Anti-Sway or a truck! All you need is a Sedan! Woohoo!!
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09-07-2016, 08:53 AM
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#8
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Does anyone have a schematic for a 91 34 fter? The manual says there are 5 low voltage wires running along the ceiling. I have 21 so i have little faith in the schematic in the manual.
I opened one of those convenient access points in the ceiling with my sheet metal shears. I hope I don't have to open any more.
You have to love them. I called and was told i was caller number one. Waited 20 min. on hold and then was told that Customer Service was not available.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-07-2016, 08:58 AM
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#9
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Rivet Master
1984 34.5' Airstream 345
Foothill Ranch
, California
Join Date: Mar 2010
Posts: 4,695
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09-07-2016, 09:21 AM
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#10
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Quote:
Originally Posted by Keyair
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This video.
says it will not find a Open Circuit behind conductive material, the Airstream body, I assume the limitation is there for a short also.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-07-2016, 09:50 AM
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#11
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Rivet Master
1974 Argosy 26
Morrill
, Nebraska
Join Date: Nov 2009
Posts: 6,014
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Howie:
Do you have a short or an open circuit?
Are you blowing fuses?
Or just not getting power to the fixtures?
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09-07-2016, 10:36 AM
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#12
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Twas a short. I had installed a new AC unit 2 weeks ago and thought the short may have been a pinched wire. Dropped the ceiling cover and mounting plate to check the wires running along the side of the AC. Could find no burn marks and the short was gone. Bundled the wire and reinstalled the ceiling plates. I hate problems that solve themselves.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-07-2016, 10:57 AM
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#13
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Rivet Master
1974 31' Sovereign
1979 23' Safari
Wayland
, New York
Join Date: Jan 2012
Posts: 1,632
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Quote:
Originally Posted by HowieE
Does anyone have a schematic for a 91 34 fter? The manual says there are 5 low voltage wires running along the ceiling. I have 21 so i have little faith in the schematic in the manual
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5 low voltage house circuits. That doesn't include wires running to tail lights, running lights, speakers, radio, tank level sensors.... It adds up and AS tries to run all the low voltage down one side, high voltage down other. So the wire bundle can get pretty thick in some places.
The wire feeding the loads you are having problems with should be a certain color from the fuse panel. That circuit and its branches will stay that color but might get stripes of white or yellow on the branches. This should help trace that one wire down.
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09-07-2016, 11:59 AM
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#14
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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For the moment the problem is solved.
Never found the short. There is no way to trace the wires in the ceiling or see where the branch off. Just dumb luck so it will return.
Yes it is easy to spot the wire in question by color if you can find access to the wires.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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09-07-2016, 12:13 PM
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#15
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Rivet Master
1984 34.5' Airstream 345
Foothill Ranch
, California
Join Date: Mar 2010
Posts: 4,695
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I bought an ECT200 and Powerprobe 3 as part of my restoration kit, and they have paid for themselves many times over already.
Yes, the ECT200 struggles a little with wires in shielded spots, but it has a couple of tricks up its sleeve...
1/ The units sends a signal down the wire, and it emits an audible beep which changes when the short condition changes.
2/ The sensor unit LED points toward the short.
In one case on my Airstream, I was chasing a dead short in the 12v feed to the horn and 12v power sockets(cigar lighters).
I followed teh wire behind the drivers side panel, where it disappeared... in undoing the screws holding the panel on, the tone of the unit suddenly changed, indicating that the short had ceased...
Upon inspection, I found this main feed wire neatly split dead center by the trim screw!
So, by using the sound of the unit, and the direction of the short indicator, you can see where you have access to the wire, which direction or run the short is.
Then pull or manipulate wires and narrow down the areas, and see and hear what causes a change.
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