What is the yellow wire?

[Victor Benz]

In this area (electrics) I am challenged. I am working my way through the trailer hitch connection. I have traced and confirmed all the wires, except the yellow wire. In my setup, the yellow wire is terminated outside the trailer. In all the wiring diagrams I have, it is always labelled Extra Auxiliary Circuit.

Terminal # 1 White Common Ground
Terminal # 2 Blue Electric Brake
Terminal # 3 Green Tail, License, & Running Lights
Terminal # 4 Black Battery Charge
Terminal # 5 Red Stop & Left Hand Turn Signal
Terminal # 6 Brown Stop & Right Hand Turn Signal
Terminal # 7 Yellow Extra Auxiliary Circuit

In your trailer, what is connected to the yellow wire? What van it be used for?

Should I the yellow wire inside and terminate it there for future purposes?

Victor

[Gina D.]

What is the yellow wire?

It's an underdeveloped red one.

(I am in my room...)

[Dan Quinn]

the yellow would be used to charge the battery while you are towing or power the tt in stead of the battery in the tt...

[Patrick M.]

It's typically unused. Here's the Scamp wiring diagram from the manual. Unfortunately are confusing as they are oriented wrong and the one on the left is a 6-pin.

The picture on the right is what Scamp mailed to me. I wired mine accordingly and it worked when plugged in!

[Byron Kinnaman]

What is the yellow wire?

It's an underdeveloped red one.

(I am in my room...)

Gina, you seem to be spending a lot of time in that room. Which end of the trailer is it?



Back on topic.

The yellow wire is as it auxillary. On my trailer it goes to the back up lights. Yup, the trailer has back up lights and really work, just like the ones on the Tow Vehicle.

[John & Sandy M]

I think the yellow wire is for stuff like back-up lights (at least thats what I was told). We have a 7 pin bargman connected to six actual tug leads. The yellow is not connected to the tug and I don't have back-up lights on the Scamp (they wouldn't be particularly helpful anyway since a little light 20+ feet behind me isn't going to help me back up in the dark... I stick my wife and a flashlight with this chore).

[Suz]

Here's Bargman's wiring diagram. The actual link is HERE>

My SUV came with the towing package so the colors are different on its wiring, but since they all do the same thing ....

[Byron Kinnaman]

I think the yellow wire is for stuff like back-up lights (at least thats what I was told). We have a 7 pin bargman connected to six actual tug leads. The yellow is not connected to the tug and I don't have back-up lights on the Scamp (they wouldn't be particularly helpful anyway since a little light 20+ feet behind me isn't going to help me back up in the dark... I stick my wife and a flashlight with this chore).

You know, I thought the same thing about the backup lights not helping. But they really light up the area around the corners of the trailer. The first night time set up I sent the wife back there with a flashlight. I could see the flashlight but not much else. Put the TV in reverse and the whole area light up. I think I'll keep my back up lights.

[Rick F. D.]

the yellow would be used to charge the battery while you are towing or power the tt in stead of the battery in the tt...

7 Way RV Connector
Pictured below is the Pollak 7 way connector, which is the connector style in most common use on RV trailers and is becoming increasingly popular on horse and utility trailers. This connector is also manufactured by the Theodore Bargman Company and there are also some generics around. They are supposed to be interchangeable and the wiring color code is maintained among the various brands.

As you can see in the illustration below the back side of the connector body is labeled at each terminal. The labels are listed below with the function assigned to that pin.

On the tow vehicle side with the exception of 96-98 Ford and Dodge pickups and SUV's with factory installed trailer wiring, wire color alone should not be relied on, always test and match the function to the appropriate terminal.

On the trailer side RV's for the most part are wired to match the connector colors. Any plug that has been changed or extended, along with horse and utility trailers should be tested when replacing for any reason to be sure the function matches the terminal.

It should be noted below that the center terminal is labeled as an auxiliary circuit, most commonly used for backup lights not a ground terminal as many try to make it.

Wiring Code 7 way Car End # Color Gage Circuit Function connector interior
1 white 10 common ground
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.

Bargman/Pollak connectors

[Roger H]

When de-fusing a Fiberstream you should ALWAYS IMMEDIATELY cut the yellow wire... oh... but FIRST...





Ok, ok... going to MY room now...

Roger

[Benny K]

I suppose the yellow wire can also be used for the high center brake light if you had one installed......personally I use it for an auxilliary ground, so it gives me two separate ground connections in case one fails.. ...Benny

[Craig Nold]

On Casita trailers, the yellow wire from the center pin (#7) goes to the backup lights. Toyota trucks with the factory tow package are also wired that way.

[Brian B-P]

I asked this question earlier, but applying to my Boler 1700. I asked because a yellow wire was running in the trailer along with other wires, and I wanted to determine what it was for. Other B1700 owners explained that it is not connected, and run to the rear of the trailer.

While the 7-pin connector standard only assigns the centre pin (normally connected to a yellow wire) as "auxiliary", and several people suggested the back-up lamp use, Boler manuals suggest using this wire for the separate stop signal - in either case, the location of the wire (runs past the left tail light and ends near the right tail light) is workable for either purpose. The separate stop wire could be used for a CHMSL (centre high-mounted stop lamp), but even without the CHMSL that wire is needed to run the stop lamps on each side if the usual left and right wires run only turn signals. In my B1700, as installed by the factory, the wire is attached to nothing but the tow vehicle connector.

This wire in my Boler is the same gauge as the other lighting wires, and thus unsuitable for battery charging - the charge line is the usual heavy black wire as described in various references.

[Frederick L. Simson]

In all the wiring diagrams I have, it is always labelled Extra Auxiliary Circuit.

Terminal # 1 White Common Ground
Terminal # 2 Blue Electric Brake
Terminal # 3 Green Tail, License, & Running Lights
Terminal # 4 Black Battery Charge
Terminal # 5 Red Stop & Left Hand Turn Signal
Terminal # 6 Brown Stop & Right Hand Turn Signal
[b]Terminal # 7 Yellow Extra Auxiliary Circuit

In your trailer, what is connected to the yellow wire? What can it be used for?

When I first bought my Fiber Stream, the previous owner was an electrically challenged Heating & Air Conditioning mechanic. All he knew was the code for 110 volt house wiring: White = Neutral, Black = Hot, Green = Ground. When he couldn't figure out the tail light color code, he bought a set of Boat Trailer tail lights, and crudely sheet metal screwed them into the fiberglass hull, right next to the originals. Then, when THEY didn't work; since 4-pin flat color code is different fron 7-pin round, He started pulling and re-arranging individual wires! He JUST KNEW that GREEN = GROUND!

To make a long story short, I completely pulled the broken & patched pigtail with molded plug, and all 4 of his botched tail lights. Luckily, he ran duplicate wiring from the front to the back of the trailer, without molesting the wires inside Fiber Stream's plastic conduit. I researched the trailer color codes and found a mention that;
[b]Terminal # 7, Yellow = Auxiliary circuit / Back-up Lights

I installed a new pigtail, with molded 7-pin plug, to a junction box that I connected to the Fiber Stream's existing conduit full of wires. I ran a yellow wire thru the conduit with the others there (yellow was not there). I installed new Tail Light Fixtures with Back-up lights. I also had to tap into the back-up light connection inside the tow vehicle in order to make a complete circuit to the new Back-up Lights.

I find Back-up lights very helpful.

[Victor Benz]

Thank you all for your help and your humour!

I now can move forward to the next challenge!

Victor

[Patrick M.]

I have update my post #4 to include the instructions sent to me by Scamp for wiring my tow vehicle. The plug diagram is better than the ones included with the Scamp manual as it is oriented correctly.