how does the trailer get power

[Rene T]

Looking at the OP’s last picture it looks like there is a gap/space between the underside of the bolt head and the star lock washer. Maybe the missing wire came from there. To the OP, check and see if you are able to move that white wire with the blue insulator.

 

[Kirk]

Kirk, are you saying test the voltage between the positive line from the converter (inside the trailer beneath the DC panel) to the black wire at the front of the trailer that i am trying to decide what battery post I should connect it to.

No that is not what I am saying. Put the positive lead of the voltmeter on this lead.

Then put the negative lead to the chassis, anywhere that you can make a good connection. It does need to make good contact so bare metal is a good place. The bare metal of that connector in the second picture is probably a good place. The wire in the second picture looks like coaxial cable. Is that what it is and if so, where does it go?

 

[John From Detroit]

Test the voltage. with trailer plugged in between the lone black wire and an unpainted chassis spot or bolt. If you have q12-15 volts paint, tape or loom that wire RED. and hook to ;positive battery.
IF not get back with us

Negative goes from battery to frame. The bolt with the star washer most likely.

 

[glrider]

Thank you very much to everyone with their comments and suggestions. I found a guy in town where we are who does RV work. With my idea of things, what people had said here, abd what the RV guy said, I was convinced the lone black lead at the front of the trailer was positive. I bit the bullet and connected it to the positive battery post and then ran another cable of the same guage from the negative post to a bolt screwed into the frame. Things in the trailer are working so we are good to go.

Thanks again to everyone.

 

[Rene T]

Did you try to tighten that bolt you show in your last picture? Is that where you connected that new black wire?

 

[John From Detroit]

I will say if the lead is in fact positive paint or loom it RED.
Like this stuff

Red Wire Loom Tubing - Split

1/4" to 1" Inside Diameter| Polyethylene | Small Footage & Bulk Boxes

www.cabletiesandmore.com

Many auto stores (Auto zone, Discoun auto O'Rileys) NAPA should have it.
RED for Positive

 

[glrider]

no there is a clamp holding the positive line to the frame so it doesn't drag down. I attached it there.

 

[Kirk]

there is a clamp holding the positive line to the frame

Did you find the problem and get things working?