Help! Scamp exterior lights stay on

[ourscamp]

After 2 short trips this summer (have had the Scamp for 5 years) we found that the exterior lights - marker and tail on both sides - just stay on. NO!! It's NOT connected to the Tow Vehicle. They stay on if connected to Only the shore power or with Only the battery in the circuit. I've redone the ground connections, cleaned and contact lube applied. I checked all the bulbs and their connections.

I know the shore power unit supplies 12 V to the system even if the battery is disconnected. The only way to kill the lights is to totally disconnect the camper from all power.

Any ideas????? Thanks ahead of time.
Bob

[Dave Fish]

As I think about the wiring systems on most travel trailers, there are three systems: A.C., 12v for the coach, and 12v for the running lights, turn, stop. The only place these three normally intersect is the battery, primarily through the charging systems.

I assume you have a hot line from your TV to charge the battery while driving. That and possibly the braking system should be the only points your TV connect to the trailer battery. Based on this analysis, I would look to see if you might have a short between the charging line and your running lights. I would look at the connector first to see if something has pulled loose but it could be further down the cables someplace.

[Gerry]

Had this problem years ago after rewiring my Boler and it was just as Dave said. Some how my charging wire was inter-connected to the charging wire from tow vehicle. I was fortunate and saw this within an hour of the weekend and disconnected the battery before I lose too much voltage and I got to looking at the bus bars I had installed and found the problem. Now I just run the charging wire direct from TV plug to posts on Battery (on tongue). When I get to destination I unplug from TV and no problem.

[gordon2]

Originally Posted by ourscamp

... we found that the exterior lights - marker and tail on both sides - just stay on. NO!! It's NOT connected to the Tow Vehicle. They stay on if connected to Only the shore power or with Only the battery in the circuit. ...

Perhaps the oddest problem I have ever seen in this forum...

The marker and tail lights are isolated from the trailer's onboard 12 volt system (converter and battery) so somehow a connection must have been made where it should not have been. Usually the marker lights positive connection is a green wire from the umbilical cord and if it becomes connected to a positive 12 VDC power source somewhere along the line, then the lights will come on. In this diagram the connections where wires cross is shown with a dot. If there is no dot the wires are not connected and you can see that there is no connection between the marker lights positive side (green) and any power source other than the tow vehicle. Of course if the wires got shorted in the umbilical plug, that could do it. If the same wires short to a ground (negative) then fuses would blow or worse.

Trace the green wires.

If any modifications have been made to the wiring then YMMV.

[Radar1]

Sounds like the 12 volt power line is somehow making contact with the running light wire. I would suspect the 7 pin connector, perhaps the wiring inside the connector itself is frayed and making contact, or perhaps the cord got pinched under the tongue at some point and crushed some wires. Are there any puncture marks on the cord where it passes close to the ball?
Second guess would be where all the wires come into the camper, perhaps something in the closet shorted out two of the wires?

[Byron Kinnaman]

As with most electrical problems it's a good idea to take to a professional for diagnosis and repair. If I had to guess I would say that the previous owner tried to mess with the wiring himself.

[Byron Kinnaman]

As with most electrical problems it's a good idea to take to a professional for diagnosis and repair. If I had to guess I would say that the previous owner tried to mess with the wiring himself.

FYI the power for the running (side lights) and tail light is supposed to come from the tow vehicle.

[steve dunham]

I would check the 7 pin cord connector on your trailer .
Water , or road salt may have caused corrosion to form in the cord cap leading to a conductive path between the 12 VDC Positive and the wire feeding the parking lights
There has been several threads on problems similar to yours and most of the time the solution was in the cord cap.
If the PO has screwed with the wiring then all bets are off.
Only God knows what he or she might have done.

Disconnect the trailer from shore power and your tow vehicle
then disconnect your trailer battery .
If the lights go off when you disconnect the trailer battery then there is a unintentional circuit path in your trailer.
My bet is it's in the cord cap.

[Gerry]

As said it was a bad connection that I had made due to my 79 Boler color scheme wasn't the standard USA trailer colors or maybe somebody got in there prior to my owning it. Shortly after that trip I tore all wires out and rewired it 100% from front to back.

[ourscamp]

Thanks All! you've all given me great ideas to check things out. I know when I'm getting 120 V thru the converter it acts the battery if the battery is connected or not, so that's probably why it doesn't make any difference which power supply is coming in (or both).

I'm the original owner and the only wiring mods I've made is to add 4 120 V outlets to the AC system - no mods to the 12 V trailer wiring at all.

I think I'll check the 7-pin trailer plug. It may have gotten a tough tug at some point going over bumps, etc.

What really baffles me is that the lights are NOT on when power is first connected. The camper can sit up to 5 hours and the they just come on!
(Play Twilight Zone music here...) And the camper is doing just that --- sitting.

I'll keep playing with it.

[Joe Romas]

Bob

You don't say how old your trailer is but like most above I believe the place to start is to replace your 7 pin cable, connector and all.
The insulation could be breaking down inside the outer jacket.

For a test I would disconnect the green wire I think is running and tail lights inside the trailer, in my Casita that's inside the closet, where the 7 pin cable wire connects to the trailer's interior wiring.

Get a genuine Bargman cable because the ends have two contacts (both sides) on the connector.

Joe

[ourscamp]

Well, most of you guys were right! Perfect example of collective brain power, and in this case, experience!

This was still driving me crazy because I took out the battery completely, and when I plugged into shore power the lights would come on intermittently! Still!!

So I started to twist, turn, pull, push on the moulded plug end (the 7 pin trailer end) and I finally got it where I could control the lights coming on and off from the same spot on the cable - about 8" from the plug.

Now, a new plug is on it's way!!

Thanks to you all!!!
Bob

[RogerDat]

Electrical is where you get to spend 6 hours to do a 1 hour repair. The other 5 is spent figuring out what in the heck is not right. :-)