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bsmith95610's avatar
bsmith95610
Explorer
Aug 29, 2016

Travel Trailer running light not working correctly

I just installed my new trailer light and now my brake lights are working correctly. I'm assuming they probably weren't working correctly due to the wiring connections and not the light itself. The issue I am having now is the lights work correctly for everything EXCEPT the right back running light does not light up when I have my headlights on. The light does work when I have the brakes pressed or the turn signal on. I'm assuming since there's only one bulb that there must be a wiring issue somewhere. What is the best way to troubleshoot that issue? I do have a multi-meter which I am a little bit familiar with using.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 29, 2016
    Brake light element working - good negative. Brown wire issue. Make sure bulb is in base correctly. Push on the bulb. Socket wire contacts go bad due to corrosion/oxidation.
  • sch911's avatar
    sch911
    Explorer
    Aug 29, 2016
    The TT light bulbs have two filaments. One for turn/stop, and one for running lights. Your running light is not getting power or ground.
  • Artum_Snowbird's avatar
    Artum_Snowbird
    Explorer
    Aug 29, 2016
    A very useful check is to take the lens cover off both light sets and look carefully at both. The thin filament is the run light, the thick filament is the brake/turn.

    Check the operation of both to see that they work the proper filament, change the bulb with the other side to see if that changes anything, and take a wire from the negative of the truck battery, to the side of the bulb at the back to check the grounding of the bulb. If you find anything with one of these, come back again.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Aug 29, 2016
    sch911 wrote:
    The TT light bulbs have two filaments. One for turn/stop, and one for running lights. Your running light is not getting power or ground.

    Since both filaments use the same ground, it shouldn't be the problem. Follow the hot wire back and you will find the problem. (Assuming the bulb filament is not burned out.)

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