Run/Nav Lights Failure Continuing Saga

[Jackson]

As previously posted my running light circuit continues to blow TV fuse on short. My attempts to chase all run light wiring for short has provided no specific answer. However, I believe to be closer to a solution as the following has revealed itself.

The TT is always connected to shore power while parked at home and not connected to the TV. One evening after dark I happened to see the entire rear run/nav lights lit up like a Christmas tree! With further inspection I was able to close the short by throwing the interior lights breaker switch.

The task now is to be able to trace the routing of the interior lighting circuit. Any advice as to how this may be accomplished would  be greatly appreciated. One caveat that has me completely puzzled is that the panel breaker has no effect on the light circuit when powered only by the 12V house battery. I cannot complete the wiring scheme in my mind.

Any and all suggestions including witchcraft will be gratefully received.

[DavidM]

Wow, that is weird! AFAIK the trailer's running light circuit is powered only through the TV's 7 pin connector and has nothing to do with the trailer's internal DC system powered by the converter breakers.

Given that the running lights lit up when disconnected from the TV while the trailer was powered by its DC system inside, tells me that there is a serious crossover between the two systems. Given that it is intermittent, it will be very difficult to diagnose. Look for places where the two systems are bundled together where there may be insulation degradation that will let the internal DC system power the running lights, although in my view there should be none, but who knows.

David

[Powder Hounds]

Hi,

I had the exact same problem except it was the rear brake lights. They would just start to glow.
It was the 7 PIN plug. The original install was faulty and caused some of the connections to short.
Take your plug apart and have a look?

PH

[Powder Hounds]

This is what mine looked like.

[DavidM]

I think I misspoke above about the two systems being separate and Powder Hounds post above gave me a thought which supports his theory:

Pin 4 of the 7 pin connector is connected to the battery so is part of the T/T's DC system. If there were a cross connection between that pin with the running/tail light circuit at the plug (pin 3), that would cause the problem Jackson is experiencing.

Check that plug for shorts/cross connections. Less likely is the distribution box on the tongue which takes the wires from the plug and connects them to the various circuits on the T/T.

Here is a drawing of the pin outs of the 7 pin connector:

David

[Merlin]

The other place wiring comes together is in the junction box attached to the frame about 3 feet back from the hitch. Find it by following the 7 pin connector wiring along the frame. If water has leaked in there or if insulation has frayed over time, there could be accidental cross connection in there. Other than that and the 7 pin connector itself, I can't imagine where a cross connection would have developed.

[Pinstriper]

They ran wires through holes drilled in the aluminum, with no reaming to remove burrs, or grommets to provide any cushion. Eventually those sharp edge cut into the insulation, and hot shorts to ground.

[Jackson]

Thanks again for your replies some of which has been discussed in my previous post. . And thanks also for this forum which is a Livin Lite life saver.

I MISSPOKE. it was not the ceiling lights breaker (fuse) that was the varying factor in the run lights illuminating with shore power but the 12 Volt AC branch breaker.

Thus, with the TT solely on shore power the rear five high red and two bumper mounted red run lights will illuminate with the 12 Volt AC breaker on. With this breaker off these run lights are off. None of the other run lights, perimeter or top forward are effected. This entire scenario is intermittent and has not been observed while on 12V house battery power.

An illogical presumption is the TV 30 amp fuse blows when this unknown 12v power source is added to the 12V TV pin#3 output creating an overload. Previous statements disprove this unless pin#4 of the trailer connection is active in the TT.

What purpose does this AC branch circuit 12 Volt breaker serve? Pin #4?

[DavidM]

A 12 volt AC breaker is an oxymoron. It is either a fuse that serves 12v loads or it is an AC breaker that serves AC loads. It can't be both.

But whatever, you will probably find the cause in either the 7 pin plug or less likely the terminal strip mounted on the tongue as Merlin describes.

David

[Merlin]

So, to summarize so far:

When the trailer/TV running lights are turned on while the 7 pin connector is plugged in between the trailer and TV, the 30A fuse serving the trailer 12VDC power blows in the TV.

Intermittently, the rear 7 running lights on the trailer (5 upper and 2 taillights) illuminate when the trailer is connected to shore power. This does not happen when the trailer is only on battery power. No other lights go on.

To follow up on David's nomenclature comments,

In the electrical panel in the trailer, there are blade type fuses in a vertical fuse holder serving the 12VDC system and switch type circuit breakers horizontally across the top serving the 120VAC system.

In my 2015 16TBS,

the 120VAC breakers, from left to right:

Main
Refrigerator
A/C
Water heater
Microwave
Outlets
Converter

The 12VDC fuses, from top to bottom:

Water pump
Furnace
Water heater
Lights
Refrigerator
Antenna booster
Propane monitor
Bed lights
Radio
(If you have a trailer tongue jack, it runs directly off the battery with it's own in-line blade-type fuse)

Since only the rear running lights illuminate intermittently, I wonder if the cross connection causing the overcurrent is someplace other than the 7 pin connector or junction box because a faulty connection there would cause all the running lights to turn on? (Unless there is a loose connection in the running lights wiring and the front/side running lights never turn on.)

There are no fuses in the trailer electrical panel for the power supplied by the TV for the brakes, running lights, battery charging, turn signals and brake lights. Those are all fused in the TV, likely via multiple fuses. I assume that's all in working order and the problem is in the trailer or trailer plug.

[Pinstriper]

Is it possible by "12 volt AC breaker" he means "the AC breaker for the 12v converter" ?

That might make sense, as the source of the short could be somewhere between the converter and the battery.

[Merlin]

Is it possible by "12 volt AC breaker" he means "the AC breaker for the 12v converter" ?

That might make sense, as the source of the short could be somewhere between the converter and the battery.

You might be on to something, because a cross connection between the converter and battery would also explain the no problems when running on just battery power.

[Jackson]

Is it possible by "12 volt AC breaker" he means "the AC breaker for the 12v converter" ?

That might make sense, as the source of the short could be somewhere between the converter and the battery.

You might be on to something, because a cross connection between the converter and battery would also explain the no problems when running on just battery power.

Correct. I am arriving at that conclusion. Which I would assume any interior DC load that would intercept the run lights circuit. As to why only the rear run lights are illuminated by the short might signify a minor contact abrasion near the back of the TT. Surprisingly none of the DC fuses are blown?

I will go back over the run light circuit to investigate a possibility or by pulling DC circuit fuses by elimination. My worst fear is the bathroom shower wall and slide out control wall which will be hard to access.

Thanks again for all the assistance. Wishing everyone a grand summer.
 

[RV Squirrel]

Sorry if this is a bit late, but it may still be helpful.  In my 2014 Camplite 14DBS, the bathroom is in the back of the trailer.  Wiring for a number of things (including the red running lights at the top of the trailer in back) run through a tray that runs the length of the ceiling in the bathroom.  Might is be possible that there is a short there?  There may be a wire for the slide out controller that runs through the same channel, and it may have shorted with the red running lights.  I have a separate fuse for the controller, but I did not notice one in the list that you provided above.  If this was the problem, and if you were able to pull the fuse for the controller, than you might have noticed the running lights going out when you pulled the fuse.

If you need to get access to the controller...  I was replacing a leaky shower faucet.  I was using a mirror to look inside the hole behind the faucet to see where the pipes went.  To my surprise, I saw the controller for the slide out!  If you need to get access to the slide out controller, that may be one way to do it (if it is located in the same place as mine).  Scary place to put it though.

[Hal_Yarbrough]

The tray inside the rear bath is exactly where I found my running light problem in my 21RBS. With no grommet where the wiring goes through the aluminum wall, it only took a few trips for vibration to cut through the insulation and short the wiring. This is probably the worst oversight I have found on my 2015 21RBS.
Halbro