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Chad_Jen's avatar
Chad_Jen
Explorer
May 14, 2018

lights on trailer on when driving

When bringing my trailer home over the weekend I noticed that the lights to my truck ('14 Chevy Silverado) were on (not just the DRLs but the actual headlights and taillights). I have the light switch set to "Auto" so I don't have to worry about them. I noticed when I looked in the mirror that the marker lights for the trailer weren't on. I think (but don't remember for sure) that in the past the lights for the trailer have come on when the ones for the truck did, even with the "Auto" setting on. I turned the knob to turn the lights on the old fashioned way and the ones for the trailer came on. Shouldn't the lights for the trailer be when the truck's are, even if the truck's selector is on Auto, or am I missing something?

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  • bobndot's avatar
    bobndot
    Explorer III
    May 14, 2018
    Might be a ground issue on the trailer. Unplug the trailer and put a tester on the 7 way plug on the truck to see if you have power at those pins. If so, its the TT and probably a ground.
  • BurbMan's avatar
    BurbMan
    Explorer II
    May 14, 2018
    Chad/Jen wrote:
    Shouldn't the lights for the trailer be on when the truck's are, even if the truck's selector is on Auto, or am I missing something?


    No you are not missing anything, that is correct. My headlights are in "auto" mode by default and when the sensor activates the headlights, the trailer running lights will come on too. Wiring is such that anytime the truck's parking lights are on, the trailer running lights are too. Note that the parking lights don't come with DRL's in the daytime, so you won't get trailer running lights unless you turn on the headlights.

    If the truck's parking lights are on but no running lights on the trailer, check the fuse in the underhood elec center and also the 7-pin connector.
  • SoundGuy's avatar
    SoundGuy
    Explorer
    May 14, 2018
    eHoefler wrote:
    Do you have anything on the dash?? There is a little dome thing on the dash, if you cover it, the lights will come on.


    What's the point when the vehicle's lighting switch allows you to simply turn the lights on? :h

  • eHoefler's avatar
    eHoefler
    Explorer II
    May 14, 2018
    Do you have anything on the dash?? There is a little dome thing on the dash, if you cover it, the lights will come on.
  • SoundGuy's avatar
    SoundGuy
    Explorer
    May 14, 2018
    I'm in Canada where DRLs have been mandatory for years. I always leave my 2012 Silverado's light switch in the AUTO mode and let it determine when full lighting should be on EXCEPT for when towing. When hitched to the trailer I always turn the light switch manually to full lighting so the trailer's running lights also illuminate, even during daylight.

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