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Trailer Lighting Problem

Discussion in 'Boats and Motors' started by RONK, Apr 4, 2005.

  1. I bought new submersible lights for my trailer. Hooked them up & the rear running lights won't work. The side running lights are on. All turn signals & brake lights work. Does anyone know where the problem could be.
  2. Hetfieldinn

    Hetfieldinn Staff Member

    Most of the time, when that happens, it has to do with the ground (white) wire. The ground is usually attached to the trailer by drilling a hole in the trailer, and aataching the ground wire to a bolt or screw, and screwing it into the trailer. The problem is, the bolt, and or trailer, gets corroded, and the ground connection stops.

    Find the ground, take it out of the trailer, and take some sandpaper or something to get back down to bare metal. Spread some dielectric grease on the bare metal, get a new washer, and do the same. Put it back, and try it.

  3. When I have a problem with some lights working and others not, it's usually the connector. Clean up the males, and do your best with the female parts. I usually take a small nail and scratch up the surface inside. Try the ground first, then the connector. It's most likely one of those two.
  4. The most important thing that I have learned is when in doubt check the ground. That darn ground can cause so many problems and unpredictable things. Hetfieldinn is right on with the cleaning up the ground wire. However what I found out on the trailer that I got with my boat a few years ago made me abandon the grounding through the trailer. I messed with my lights for quite a while and could not resolve the problem so I went and bought a new kit. I figured the problem must be in the wires somewhere. I took the new kit and laid it out behind my vehicle and tested it and it worked like a charm. I proceeded to install the kit on the trailer only to find out that I was right back where I was before. My lights would work partially until I would turn on the headlights and then I lost everything. What I found out was the person that had the trailer before me had recently repainted the trailer. Evidently to do so they had taken it apart at the wishbone area of the frame in order to paint it. By doing this they had coated the metal to where the ground from the lights was unable to travel back to the trailer hitch. Therefore I went and bought a separate single strand wire and installed a ground wire to the lights on each side and have not had any problems since.
  5. Check to make sure all the electric currents are working correctly at the car/truck. Sometimes one of those connectins will fail.
  6. Lewis


    My vote goes for a bad ground.
    After cleaning and verifying that you are getting a good ground,if you still have problems the brown wire is the taillight circuit.
  7. Hetfieldinn

    Hetfieldinn Staff Member

    Another thought here. Do you have a newer truck that has a separate fuse box for your trailering wiring?

    I was pulling two different trailers out of the backyard the other day, and I hooked up the lights just to check them out. I noticed that on either trailer, the right turn signal wasn't working. I popped off the cover of the secondary fuse box, and sure nuff, the fuse for the right indicator lights was blown.
  8. If your side marker lights are working, it is probably not a bad plug at your. The side marker lights run off of the same circuit as your rear running lights. It has to be it can be a bad ground, but it would have to be common to both lights and they both ground individually. I would look first at the hot wire between the side marker lights and the rear running lights. If you used the blue wire splice taps, they are easy to not get seated completly. That is where I would start.
  9. First clean all the connector prongs (male and female)with muratic acid and then neutralize with baking soda mix. Then clean and re-attach your ground or better yet, wire a ground connection. You can do this for each light and eliminate a lot of future problrms. As others have noted, check all fuses'. Check bulbs and bulb socket for corrosion and clean with muratic but be sure to neutralize. Use a conductive grease on the bulbs and sockets. All this takes time, two to three hours, but should give you a trouble free season. I gave up on grounding to the trailer frame and have not had problems for three years other than bulb and socket normal corrosion.
  10. Tee

    Tee Team OGF

    HERE is a trailer wiring diagram if you have some questions.

    You'll be :T soon!

  11. Thanks for the input. I will deal with it tonight. If I wire a ground from each light in the back which color wire should I connect it to?
  12. What you will do at that point is run one wire back to each side and connect them to the ground wire that you normally mount to the trailer. On the back end you can mount them to the light frame. I think I mounted them under the light fixture where the light would be making its ground connection to the frame. I put a round connector on them and put them inside the bolt. This ensures that the ground will travel up the bolt and into the light fixture the way it is designed to in the first place. I hope this makes sense.
  13. I agree with Leeabu. Use a simple test light and check the brown wires at the rear of the trailer. You may have lost the connection between the marker lights and the rear running lights. In most instances with a bad ground the rear running lights may work but will dim or go out when you mash the brakes.
  14. Thanks for all the info. I know what to do now. That's what this board is all about. Now if someone could just tell me when, where, & how to fish I'd be all set. LOL