Forum Discussion

Iceworm's avatar
Iceworm
Explorer
Feb 29, 2020

Locating trailer hot wire underhood source 2017 GM

I am looking for the hot trailer wire source under the hood of my 2017 GM Sierra 3500. It is always hot at the trailer plugin. I would like to run the power wire via a constant duty solenoid powered by the ignition. That way it will only be hot when the key is on to prevent my truck battery from running down when using the camper batteries. It was easy to do on my older trucks prior to 2016 but the new ones.....not so much! Anyone done this on the newer GM's? Thanks
  • BFL13's avatar
    BFL13
    Explorer II
    Feb 29, 2020
    Whatever they did to the set-up after the change, can't you still just pull the 40a fuse in Stud 1 ?
  • mchero's avatar
    mchero
    Explorer
    Feb 29, 2020
    Sounds like that will be a tough find. Fuse under the hood or inside the cab? If under the hood can you remove the fuse block to get a look at the backside and possibly trace the wire?
    Keep us posted on your progress
  • opnspaces's avatar
    opnspaces
    Navigator II
    Feb 29, 2020
    my 2001 Suburban has at least 4 separate trailer wiring fuses and the labeling stinks. So I imagine your 2017 has at least that many. And all labeled in some strange language.

    In the end I just went to the bumper and shorted the 12v power to ground and blew the fuse. Even then it took a while to find the blown fuse because it was a physically larger 30a fuse. And not one of the little mini fuses. Oh and it was under the hood in the fuse and relay box.
  • bucky's avatar
    bucky
    Explorer II
    Feb 29, 2020
    Unplug the trailer. When you check the lights before leaving plug it back in.
  • Pipeman's avatar
    Pipeman
    Explorer
    Feb 29, 2020
    I've made it a habit to unplug from my 2011 GMC dually everytime we stop for the night or not going to be traveling for a day or so and not unhitching. The one time I didn't unplug my truck batteries in my 2001 GMC went dead after leaving the trailer plugged in over night before leaving on a trip. Maybe the batteries were going bad at that time but it never happened again because I unplugged. My 42 cents worth.
  • rrupert's avatar
    rrupert
    Explorer
    Feb 29, 2020
    The owners manual usually has a section that shows all the fuse locations. That would be a starting point.
  • KD4UPL's avatar
    KD4UPL
    Explorer
    Mar 01, 2020
    Unless they've changed from earlier models it will be one of the studs on the under-hood fuse block. I don't remember which one. The fuses are labeled stud #1 and Stud #2 I think. It's either a 40A or 30A fuse.

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