Marker lights

[Roughing it]

Hello All new to Montana just picked up 377fl yesterday was going threw some things today and when hooked up to my truck I noticed my marker lights would not work all other lights work brack turn and reverse my truck says check rear lamps if I rotate my truck light switch my front marker lights will come on for a second then go out but the rear will never light up tryed fuse on camper plug and it blew does anybody know we’re I should start looking I know it’s under warranty but cost me $180 to drive down and back to dealer so if I could fix it would be great

[BB_TX]

By “tryed fuse on camper plug“ I assume you mean you put a fuse across the pins on your 7 pin cord connector. Definitely sounds like a short in your trailer wiring. That’s the easy part. The hard part now is where.

I would start in the pin box junction box where the trailer cord connects to the trailer wiring. You will find the cord wires wire-nutted to the trailer wiring. Look to see if any of that wiring has come loose. And see if wire colors match up. If that all looks good then it gets even harder.

[Roughing it]

I did remove the cover on the 4x4 box and all wiring in there looked good

[BB_TX]

Your marker lamps and taillights should be wired together to the same cord wire. Do your tail lights work?

[Roughing it]

No tail lights do not work

[BB_TX]

Is there more than one trailer wire connected to the cord wire for the tail/marker lights?

[Roughing it]

That I don’t know it’s a 7pin connector that goes into truck

[BB_TX]

My question is in regard to the tail/marker wire connections in the pin box junction box.

[Roughing it]

No I don’t believe so it was a brown wire and there was no other wire hooked with it

[BB_TX]

The tail/marker light wire from the cord should be a green wire. And that wire should connect to one or more green trailer wires that go to your lights.

[Roughing it]

I see the green wire and it is only hooked to itself

[BB_TX]

Not sure what you mean by hooked to itself.

There should be one green wire coming out if the cord. And there should be one or more green wires coming from the trailer. And those wires should be connected together.

[BB_TX]

Can you post a picture?

[Roughing it]

I can tomorrow it’s a little dark out right know but there is the green wire from cord and only one green wire from trailer and they are hooked together

[BB_TX]

OK. Got it. That’s the bad news. That means all market lights and tail lights are daisy chained together. And no way of knowing the wiring sequence.

I would start tomorrow by disconnecting the green trailer wire from the green cord wire and see if the fuse blows. If it blows when connected but not when disconnected then definitely a short in the trailer.

[Roughing it]

Ok thank you I will keep you posted

[BB_TX]

Check those green wires carefully for any insulation damage that might ground out to the metal box.

[OldJimi]

Do you have an ohm meter or a continuity tester? I don't know if you would want to try this, but if you do, with the trailer unplugged, check to see if your green wire is shorted to the chassis. No? This isn't going to help you. Yes? Then go around and start undoing all your lights one by one and checking to see if the green wire is still at chassis ground. If you pull one light and the ground wire is not longer shorted, then replace the culprit.
Inspect all the wires you can see when your doing all this to see if the hot wire is pinchd or rubbed and touching the chassi or another wire.
Hope this helps, it's what I would do, but that's no guarantee that its the best solution.

[Roughing it]

Update
So thought about this today at work and front marker lights would come on for a second but nothing in rear so I dropped the under belly in the rear and found wire cut and grounding to the frame I don’t know why the factory would run all the wires back there under the frame next to the underbelly we’re they angled the rear this is a rubbing point due to the drop frame although this is not we’re I found the bare wire spent the rest of the night moving all the wires all lights work now thank you for your help

[BB_TX]

Great to hear it turned out that easy to solve, although it never should have happened in the first place.

Won’t go into the whole long story, but when I first got mine some living room outlets and the refrigerator worked sporadically. After a lot of dealer tech troubleshooting and me trying to explain what was happening we finally figured out those things were wired to the load side of the ceiling fan switch. Fan on and they worked. Fan off and they didn’t.