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How to diagnose tow vehicle light issue?

Discussion in 'Towing' started by smf834, Oct 15, 2019.

  1. Oct 15, 2019 at 7:50 PM
    #1
    smf834

    smf834 [OP] Member

    Joined:
    Aug 14, 2019
    Member:
    #302217
    Messages:
    20
    I am trying to get my first gen taco ready for towing. I bought it used, and it came with a uhaul tow package with 4 flat connector. It seems to only work with the right turn signal, and nothing else shows up on my tester. I followed the 4pin connector to the base of the left turn tail light and found the control box, and a single green wire spliced into the group of wires to the right turn signal. So basically, right turn signal works fine, ie green wire connects correctly, i assume? What else can i try to find out why the left and brake light are not working?

    Just to clarify, all lights on the truck work properly.

    Thanks for all the help!
     
    huachuca likes this.
  2. Nov 26, 2019 at 6:29 AM
    #2
    Mtn Mike

    Mtn Mike Well-Known Member

    Joined:
    Oct 29, 2017
    Member:
    #234494
    Messages:
    754
    Gender:
    Male
    First Name:
    Mike
    Spokane, WA
    Vehicle:
    2017 TRD OR AC
    Are you testing the tow connector pins using a meter or are you using the lights on the trailer to test? Assuming the first, you could test each wire at the point after the splice to see if the splice was bad, but it sounds like maybe the tow light control box is faulty. That's pretty common. Sometimes all it takes is a short on the trailer to kill one of those control boxes. The good news is they're easy to replace and plug and play. You don't even have to splice.
     

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