I NEED LIGHTS AGAIN.

You are looking the wrong places. The most common issue would be the Bargman connector either on the trailer or tow vehicle side.

Had a similar problem. The 7 pin plug from to tow vehicle had a loose wire in it. It was caused by pulling on harness and not plug itself to disconnect. I rewired the plug connections and it fixed the problem.

90% of the time an exterior lighting issue is a grounding problem. RVs are notorious for bad grounds. Using a test light at each light fixture is the best method. 12 volt systems are pretty straight forward - if your test light says there is power at the lamp and it does not light than the ground is bad. Could be as simple as a loose or rusted screw. Usually each light fixture has it's own ground.

Get a test light and a roll of 12 gauge wire. Hook the wire to the negative side of thetow vehicle battery so you have a good ground, then connect the ground side of the test light to the wire. Connect the trailer pigtail and turn on the tow vehicle lights. Go to each trailer light and check for power now that you know you have a good ground. If there is power at the lamp and it does not light than the ground is bad. If there is no power with that good ground to the tow vehicle battery then you have an open (break) in the positive wire before it gets to that light.

In spite of my first statement above, one light working and all the others out makes me think there may be an interruption in the positive feed. Those lights may be in series and a broken wire will kill all the lights downstream from the break. Quite often you can see a lot of the wiring from underneath the trailer.

The marker lights, tail/brake lights etc, are not connected to the trailer chassis battery, but receive there power from the tow vehicle through your 7 pin plug. Check that connection box near your plug while plugged into the tow vehicle.

Beverley and Ken

Fisherman, you have me thinking. Thanks

I think I have replaced all the required parts. I think whatever is wrong is something simple. There is a junction box on the frame, at the end of the 7 pin female plug. I have not into there yet. I can usually fix everything but the crack of dawn or a broken heart, but electrical is my weak point. Is there a module or something in that junction box?

Many of the exterior lights may be grounded through the metal siding if your rig is aluminum siding. Check all of the screws inside each exterior light fixture and tighten them. You may be lucky enough to find one that... (when grounded properly)... will turn all of your lights back on!

Moved from Forum Technical Support

1) Get either a 12 volt test light or a cheap meter and learn to use it
2) pay someone that can use one
It's simple to chase something like this with the proper tool and expensive to just throw parts at it
Good Luck, Mike