Trailer lights not working

[Joeprunc]

When the trailer ground was torn off the trailer, I had all lights working except for the parking lights (I'd find a good clean spot and ground the white wire on the trailer before trying to diagnose the issue). Also make sure the white wire on the truck is properly grounded too.
The next step I would to is grab a battery and connect a wire to each terminal. Start from the source and work towards the battery. You dealer said your truck is putting out the proper signals so start from the trailer connector. Ground the neg (or hook it to the white wire) and begin to connect the pos to the other terminals on the connector. See if you get anything...if not move back to the next available exposed wire. Once you find you lights work, the issue will be between the last two test points.

Also I find for some retarded reason that my brake lights will not work properly unless I stand on the brake pedal for 10 or so seconds....maybe there is a capacitor in the system that needs juice before it works properly.

[jwanck11]

Thanks Joe. That is exactly what I was going to try... using one of the boat batteries.

Then again, I am soo inclined to head to the local trailer shop, buy a new wire set for 15 and fish all new...

[Joeprunc]

Its seems funny that the lights went out 100%. Which leads me to believe the issue is still at the truck, or ground related. I know you had the dealer check the wiring harness, but I'd double check it again with a volt meter. When the common is connected to the white prong (the exposed one if the 4 pin system) I get around 11.5 volts when I connect to the other pins with the lights on (via brake or parking lights). If you dont' have a volt meter, you can even wire a bulb to test it.

Good luck, I hate electrical issues!

[jwanck11]

The truck tested OK a second time today. I even had a neighbor hook up to the trailer with his vehicle and nada.

I think it is actually a short somewhere in the tubing of the trailer. All of the electric is being fed to the short and there is none to hit any of the lights...

[Dave S]

How old is the trailer? The wire insulation could've broken away from being old and brittle and is now shorting out somewhere. This happened to me on a 5 year old boat stored in a garage. I had to rewire and all was good again. Maybe just rewire trailer?

[Dave S]

If I was up there, I would help ya.

[Dave S]

Have you been in the water yet, despite no trailer lights? Is it warm enough yet?

[jwanck11]

I ended up re-wiring the trailer and re-lighting it too. Its all good except for the license plate illumination (had to order that one.) It was a grounding issue in the end. The wires were actually OK, but the good thing is that the wiring/lights ought to be good to go for awhile.

The bad thing is that the trailer is rusting apart from the inside and it is happening pretty quickly.

We are going to put it in the water this weekend. Still a bit chilly to get into the water yet. This will be a test run as it is new water (river) and I want to see how the boat makes out in the first trip of the season.

[Nobody]

So I hooked up the electrical harness from the trailer to my new truck. turned on the lights in the truck and nada.

Not a single light on the trailer lit. I cleaned all the contacts to where there is shiny metal and the same thing.

Does anyone know:

1) Whether there might be a fuse between where the wires are spliced into the trucks brake lights and the harness (couldn't find one).

2) If one light is out, does that mean all lights on the trailer would be out?

3) Could a bad ground/short somewhere in the wiring in the trailer be taking out all the lights?

Where would you start to look?

I plan on running bare wires from the truck harness to one of the lights to see if it will shine. Any other suggestions?

Can we assume it's a Ford?