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  1. #1
    Member
    Join Date
    Dec 2017
    Location
    Pfafftown NC
    Posts
    102

    Only and always reverse lights

    Okay fellas, I’m sorta bummed right now and could use some words ofwisdom. It has been a couple of months since I have been able to getout fishing and finally was planning on going tomorrow. Thisafternoon checked and loaded gear and hooked up to truck so would beready to go in morning. In checking lights discovered problem. Withtruck in park and lights connected, first thing I noticed is norunning lights. Then I realized, even with truck in park, truckback-up lights were on. Checked and trailer reverse lights were alsoon. Strange! Unplugged trailer lights, back-up lights on truck wentout. Reconnected lights truck back-up lights on even with trucklights turned off. Checked turned signals and brake lights and workedon truck but not on trailer. However at all times reverse lights ontrailer are on no matter what, so long as trailer plugged into truck,and always lit on truck too. My truck has a round 7-pin and thetrailer has a flat 5-pin so I have an adapter. It is molded with the7-pin on one end and the 5-pin molded on the other. I know what I ammost likely to hear, because it is the BBC default for lightingissues “gotta be the ground” and it may be. I was frustrated andit was dark so I didn’t really check anything out yet but it seemsstrange that whatever it is would cause the truck back-up lights toalways be on as soon as I connect up.

  2. Member
    Join Date
    Oct 2010
    Location
    Fort Worth, TX
    Posts
    205
    #2
    Sounds like the trailer reverse lights are getting a +12V somewhere and it is back-feeding through the trailer connector which is lighting the trucks backup lights. First place I would look is the 7pin connector and see if there is a short possibly between any of the connections. The center connector should be the backup lights.

  3. Member
    Join Date
    Apr 2012
    Location
    Insomnia, near Seaford Delaware
    Posts
    35,449
    #3
    Might be corrosion in the 7 pin connector or the ribbon connector. Sounds like there's a short between the +12 volt pin in the 7 pin and the backup/solenoid wire on the trailer. Also sounds like the trailer isn't grounded.
    Do any work on the 7 pin connector lately?

  4. Member
    Join Date
    Dec 2014
    Location
    Highland, Illinois
    Posts
    2,738
    #4
    What did you find?

  5. Member
    Join Date
    Mar 2015
    Location
    Bixby, OK
    Posts
    2,278
    #5
    Had a very similar problem with mine and spent a while trying to track it down. Turned out to be the tag light on the trailer had a dead short in it. I unplugged it, and everything worked as it should. Since trailers aren't tagged in OK, I didn't bother replacing it.

    In the process, I also found that the 2 front side marker lights on my trailer (that didn't work) were wired backwards and never could have worked. The LED bulbs in them are positive/negative specific and the mount they fit into, which grounds them to the trailer, had the ground on the positive pin of the light.