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04-29-2007, 07:34 AM
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#1
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Silver Mist
Currently Looking...
Riverhead
, New York
Join Date: Aug 2006
Posts: 3,011
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Tracing a short
I have one taillight, right signal/stop that keeps popping a fuse.
The thing is it works for periods of time with no problem.
What is the best way to trace the cause?
__________________
Bob
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04-29-2007, 08:58 AM
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#2
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Site Team
2002 25' Safari
Dewey
, Arizona
Join Date: Mar 2005
Posts: 15,615
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Quote:
Originally Posted by LI Pets
I have one taillight, right signal/stop that keeps popping a fuse.
The thing is it works for periods of time with no problem.
What is the best way to trace the cause?
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Is this problem with your trailer or your truck? Either way, electrical shorts that come and go are not easy to resolve. It may be caused by a wire that has been exposed by a cut or wear and is grounding to the frame at times. I would pull the light and look for any wear or cuts in the wire. Next would be to connect a Ohm meter to the failing circut and move the wire while looking at the meter. When it goes to 0 Ohms you have your short.
__________________
Richard
Wally Byam Airstream Club 7513
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04-29-2007, 09:00 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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Well you can look in the areas that you have access to, inside the light fixture itself and along the line cord at the front of the trailer. While these are not the likely places for a short check them anyway to be sure. If nothing is found there and assuning you are not interested in tareing open the inside of the trailer I would consider running a new wire.
If it comes to that I use 1/4 in tubing, copper or aluminum, hung on the underside of the trailer as the easyest way to run the wire. Fishing up from the bottom of the trailer to the fixture will be a challenge but may be necessary.
__________________
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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04-29-2007, 12:53 PM
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#4
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Silver Mist
Currently Looking...
Riverhead
, New York
Join Date: Aug 2006
Posts: 3,011
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I will try the ohm meter, I figured the new wire deal already Howie, a real pia.
What about trying a 15 amp fuse instead of the 10 amp?
By the way there is no fuse in the trailer, it is popping the TV fuse for that trailer circuit.
__________________
Bob
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04-29-2007, 02:59 PM
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#5
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Site Team
2002 25' Safari
Dewey
, Arizona
Join Date: Mar 2005
Posts: 15,615
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Quote:
Originally Posted by LI Pets
I will try the ohm meter, I figured the new wire deal already Howie, a real pia.
What about trying a 15 amp fuse instead of the 10 amp?
By the way there is no fuse in the trailer, it is popping the TV fuse for that trailer circuit.
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If you have a short, 15 amps will blow just as fast as a 10 amp.
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Richard
Wally Byam Airstream Club 7513
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04-29-2007, 03:07 PM
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#6
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More than one rivet loose
Currently Looking...
Los Alamos
, New Mexico
Join Date: Feb 2006
Posts: 3,756
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If there is a 10 Amp fuse then the wire was size to "carry" approx 10 Amps. Putting a 15 Amp fuse in there could lead to over heating the wire, melting insulation and a fire. Bad idea.
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Michelle TAC MT-0
Sarah, Snowball
Looking for a 1962 Flying Cloud
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04-29-2007, 06:12 PM
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#7
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Rivet Master
1973 31' Sovereign
Danielsville
, Georgia
Join Date: Feb 2004
Posts: 904
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Bob,
I had problems with my '72 Overlander that way and blew the fuse on the TV. (I spent two hours in Chattanooga on the first leg of a very long journey to Colorado trying to hunt it down.) I did the best I could at the time but swore that one day I'd fix it for good. (The day I sold it, I spent an hour with the new owner trying to fix it again at the end of my driveway.)
With my '73 Sovereign, it was a completely different story. I yanked out all four rusty light cups and replaced them with some new modified Trucklite TL 3710s. They're sealed up, in place, and work great. (I purchased 12 new marker lights as well. For less than $100, my light problems were solved.
Unless you've completely replaced the light fixtures, I'd start there. It's possible that your wires could be messed up but much more likely to be back at the taillights. Faulty grounds and intermittent shorts will drive you nuts.
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04-29-2007, 06:29 PM
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#8
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Rivet Master
2008 27' Classic FB
1959 22' Flying Cloud
fairview
, New Mexico
Join Date: Mar 2005
Posts: 575
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Does the fuse blow when you leave the umbilicle cord hooked to the TV. What I mean is disconnect it from the trailer while still connected to the TV. Maybe the wire has come loose in the plug and the tailight wire is touching the ground in the plug.
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04-30-2007, 06:20 AM
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#9
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Silver Mist
Currently Looking...
Riverhead
, New York
Join Date: Aug 2006
Posts: 3,011
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Quote:
Originally Posted by PizzaChop
Faulty grounds and intermittent shorts will drive you nuts.
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But I wouldn't think a faulty ground would pop a fuse, would it?
Before I left for Springstream I pull apart the 7 wire harness and found the brown wire (the right signal/stop) touching another.
I fixed that 100%, checked it on the way down it was out again.
At the lake I replaced the socket wire lead with a new one from NAPA, all worked went to Elkmont, TN Phil & Laura were behind me all was good.
Checked again before leaving all good. By night time it was out again.
Do you think it's worth replacing the ground wire to the light can in a new spot?
I'll try anything before running a new wire.
__________________
Bob
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04-30-2007, 08:17 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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If you are not blowing a fuse in the TV without the trailer lets assume the problem is in the trailer and look in that direction.
Get a packet of 7.5 amp fuses. I say a 7.5 amp fuse because you are not loading the circuit with the TV lights, just the Right brake/turn lamp.
At the trailer cord plug put a fuse between the Trailer Battery terminal, just left of the key when looking at the plug end, and the Right turn terminal, at 9 oclock when looking at the plug end. With the fuse in place it may blow as soon as you attach it or it may hold. If the fuse blows at once disconnect the Right turn signal wire inside the trailer, from the trailer wiring and attempt the test again with a new fuse. If the fuse blows again when you put it in the problem is in the plug or cord if not it is in the trailer wiring.
If the fuse holds when you started the test and with the fuse secured in place flex the cord itself and flex and shock it at the plug end attempting to simulate road movement and vibrations. If you can cause the fuse to blow while moving the cord/plug the problem is in the cord or plug.
If you can't get the fuse to blow with these tests remove the right brake bulb a hook up the trailer and take it for a ride down a bumpy road. If it blows under this condition I think you are looking at a short in the trailer body.
__________________
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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04-30-2007, 10:59 AM
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#11
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Rivet Master
1973 31' Sovereign
Danielsville
, Georgia
Join Date: Feb 2004
Posts: 904
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Bob,
A faulty ground won't blow a fuse but an intermittent short will.
The taillight cans don't have a ground wire but ground to the aluminum housing. I can't speak for your 7 pin connector but I know for a fact that an intermittent short at the can will blow the fuse in the TV because it happened to me.
I've spent hours on the Overlander trying to pin it down (ground or short) and I don't have the patience anymore. (That's why the Sovereign has all new lights)
Assuming your TV plug is good and your umbilical plug is good, it is most likely at the light. (It is probably worth checking the backside of the umbilical cord plug at the front of the coach.) The light cans are what get corroded. (At least they were on both my '72 and '73.)
Using a 12v test light, grounded to the aluminum housing, you should be able to test all your wires. (I can't remember the color codes anymore except that the black is to the back-ups, and the other 3 are red, green, and brown.) If all the wires are good, replace your lights. It's a one time deal.
Pulling wires out would be an absolute last resort as your problem is most likely at one end or the other.
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