Help, mid-trip brake light issue

[Fasttimes]

Spoke to a local shop that I'm on the 4 week list about this issue and off the top of their head they felt the junction box at the front of the trailer would be a good start to find the issue.



So today I popped off the junction box and just tried to follow wires and I'm just confused to what I'm seeing.



The light that was having the issue was the passenger-side right light. I can see the color of the wire leading from the light socket is yellow. Guy at shop said I should see the wire coming into that junction box and to check it's connection.



This is where I get stumped. The only yellow wire I see is clearly coming from the trailer plug line and not from the wires that come from the left side of the junction box that lead to the wiring of the trailer. I do not see how this yellow line would have been connected to any other wire. I see no loose wire. The terminal plug on it does not seem to have space that would indicate a wire was there but came loose.


Further more confusing, is when looking any 7-pin wiring plug diagram all of them indicate that the yellow wire is the left-hand turn light, but this is on the right-hand turn light.I popped open the left-hand light to see the color and it is green.



So I a yellow wire that seems to be not connected to anything coming from the plug, and wiring diagrams that indicate the wrong color wires on the left and right hand lights.


In the pics, the upper right of the box is where the lines come in for the trailer plug. The upper left is the wires coming from the trailer.



All was working fine till this incident. Also I have a picture about a year ago of the junction box I took for another issue back then and I see the yellow line is not connected to anything back then.




Also, apparently Winnebago does not have wiring diagrams for our towables??? How ridiculous is that?


Very confused.

[SonofBert]

Originally Posted by Fasttimes

Spoke to a local shop that I'm on the 4 week list about this issue and off the top of their head they felt the junction box at the front of the trailer would be a good start to find the issue.



So today I popped off the junction box and just tried to follow wires and I'm just confused to what I'm seeing.



The light that was having the issue was the passenger-side right light. I can see the color of the wire leading from the light socket is yellow. Guy at shop said I should see the wire coming into that junction box and to check it's connection.



This is where I get stumped. The only yellow wire I see is clearly coming from the trailer plug line and not from the wires that come from the left side of the junction box that lead to the wiring of the trailer. I do not see how this yellow line would have been connected to any other wire. I see no loose wire. The terminal plug on it does not seem to have space that would indicate a wire was there but came loose.


Further more confusing, is when looking any 7-pin wiring plug diagram all of them indicate that the yellow wire is the left-hand turn light, but this is on the right-hand turn light.I popped open the left-hand light to see the color and it is green.



So I a yellow wire that seems to be not connected to anything coming from the plug, and wiring diagrams that indicate the wrong color wires on the left and right hand lights.


In the pics, the upper right of the box is where the lines come in for the trailer plug. The upper left is the wires coming from the trailer.



All was working fine till this incident. Also I have a picture about a year ago of the junction box I took for another issue back then and I see the yellow line is not connected to anything back then.




Also, apparently Winnebago does not have wiring diagrams for our towables??? How ridiculous is that?


Very confused.

I wish I could help you with the wiring. All I can suggest is go through each connection in the junction box and make sure they are corrosion-free. If not, disconnect one by one, clean it, dab anti-ox on, reconnect.

Actually thanks for this thread, reminds me I should look at the junction box on my new 1706fb and make sure the box is sealed from the elements. IIRC, my previous 1706fb I dug into the junction box when replacing the breakaway and did some sealing. Box looked like it should be an interior box, not exterior.

[BobC]

The color change doesn't surprise me. The yellow wire at the light could just be a short lead that's part of the socket and it may be spliced to another wire for the run to the front of the trailer.

A multimeter should help sort things out. In order to check continuity from the front of the trailer to the back a long wire with alligator clips will work. Alternatively a long extension cord, some short wires and some alligator clips will work (or even a helper to hold the wires together).

And double check the ground at your light. This is a common point of failure.

[Fasttimes]

Originally Posted by BobC

The color change doesn't surprise me. The yellow wire at the light could just be a short lead that's part of the socket and it may be spliced to another wire for the run to the front of the trailer.

A multimeter should help sort things out. In order to check continuity from the front of the trailer to the back a long wire with alligator clips will work. Alternatively a long extension cord, some short wires and some alligator clips will work (or even a helper to hold the wires together).

And double check the ground at your light. This is a common point of failure.

Yesterday I took a bit of wire and placed it in the 12v #4 slot and tried to test the lights there. I placed in #3 and the running lights came on. Placed in 5 and got nothing. Placed in #6 and both rear lights came on, albeit dimly but this is a thin speaker wire I'm using.



My biggest confusing is that I do not see any wires from the trailer connecting to the yellow wire from the trailer plug. Furthermore, the green wiring branches off at the terminal crimp. Green wire seen coming from trailer plug on the right, green wire coming from trailer wires upper left both connected at terminal crimp. But from this crimp a third green wire leaves the crimp and junction box with a white ground wire into the nose of the trailer. I can only assume this may lead on back to the rear lights, but it's just an assumption.



Now if both brake lights were somehow all crimped together then perhaps this has been some hack job I haven't noticed in the 3 years we've owned it, but I doubt it. Can't say I've ever really went and check if right light is working, then left light is working. Usually I turn on hazards and if I see them flashing I assume all is good. But sure seems to me if both lights are crimped into the same green line then they would not be able to work independently to blink.



My trailer plug line has a small bit of damage to it, clearly it got pinched by the trailer at some point. Thinking this could be perhaps a culprit of issues I started looking at new ones online. On one Amazon posting a person posted his post-install picture of the new junction box and sure enough the yellow was not connected to anything as well. The rectangular neat junction box pic below is that persons set up. Clearly yellow post from plug is not connected to any other trailer line. So now I'm really confused.


I'll see if I can rig an extended testing wire.

[Inventor]

The pinched cord is undoubtedly the culprit and should be repaired or replaced; if you carefully open the "wound" shown in the photo, you are likely to find the offending turn/brake signal wire bared and crossed with the aux-power wire.

[Goodspike]

From another thread, those two posts in the bottom picture (one of which has three yellow lugs connected to it), may be a type of circuit breaker, where they have a small reset button on them. Probably not the problem here if it's just one light, but something to check out.

[Fasttimes]

Originally Posted by Inventor

The pinched cord is undoubtedly the culprit and should be repaired or replaced; if you carefully open the "wound" shown in the photo, you are likely to find the offending turn/brake signal wire bared and crossed with the aux-power wire.

Yep, this is the issue. I opened up that "would" and found all kinds of a mess of smashed wires. I separated the wires and decided I would try a fix versus replace for now. I got some marine grade heat-shrink butt connectors and cleaned up the wires, connected them and then wrapped each connection in electrical tape. I think tucked them into the remaining original cable shielding and mummified it with electrical tape.


Lights are working in my initial tests. Still can't explain the wiring I see in that junction box. Hard to track down each connection. But I'll take working for now.

[Inventor]

Glad you got it sorted out..... although, to be on the safe side, I'd recommend that you replace that cord in the not too distant future.