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Hazard lights engage trailer brakes

Discussion in 'Towing and Hauling' started by Matt_INW, Sep 23, 2016.

  1. Matt_INW

    Matt_INW Full Access Member

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    Yup it's wierd.

    Got a 5th wheel and turns out the hazard lights are engaging the trailer brakes. All other light and brake functions are normal.

    The truck was wired years ago by the original owner. I assume professional install because it also has a receiver hitch and under bed gooseneck and 5th wheel support installed. I don't know if it's always been like this or a problem that has cropped up.

    Any recommendations on where to check?
     
  2. 79jasper

    79jasper Chickenhawk

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    You should look at the wiring.
    See how it's hooked up.

    Sent from my SAMSUNG-SM-G935A using Tapatalk
     
  3. Matt_INW

    Matt_INW Full Access Member

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  4. 79jasper

    79jasper Chickenhawk

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    I was actually wondering about that.
    But didn't wanna sound crazy. Lol
    Probably normal, since in essence, it is apply the brake lights.

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  5. laserjock

    laserjock Almost there... Supporting Member

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    My 88 did that. The problem is likely that the hazard tail light signal is feeding back through the multifunction switch and to the brake light switch. A properly placed diode would stop it but at this instant, I couldn't tell you exactly where to put it. I haven't got that far along yet.

    Its a handy feature when you are checking lights and brakes on the trailer though, pull the 4 ways and turn on the parking lights and you can check everything at once with no helper. ;Sweet


    On Edit: I went back and looked at the thing you linked. That is a fancy way of mounting a diode. It is stopping the tail lights from backfeeding to the brake light switch where your brake controller ties in. So basically, you need to go to the tail light side of your splice for the tail lights and add this diode in between the brake controller splice and the tail lights. If you buy your own diode, make sure you point it the right way when you splice it in. If you put it in backwards, the brake lights won't work and your brake controller will pulse.
     
    Last edited: Sep 27, 2016
  6. Sidewinded_idi

    Sidewinded_idi Full Access Member

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    My truck does it as well. I personally like it as when loading/ unloading I turn the controller all the way up and put my hazards on and it’ll lock the trailer brakes solid
     

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