# No Power at 12v Trailer Plug.....09 GMC



## G.Landscape (Oct 20, 2011)

So I am trying to hook up a set of Aux backup lights through the trailer plug. I originally had NO power to the 12v terminal at the plug and after going through this walk through (http://www.silveradosierra.com/how-...nt-12v-power-for-7pin-trailer-plug-t1712.html) I am now getting a reading of like 1.5v.

Can anyone shed any light on this?


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## Triple L (Nov 1, 2005)

are u using the live all the time or the backup lamp wire? put the truck in reverse and it should power up...
Did you check the fuse's?


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## Cosmic Charlie (Feb 1, 2009)

Trailer plug has separate breakers under the hood & has nothing to do with the tail lights ...


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## G.Landscape (Oct 20, 2011)

OK....so I have basically built my own back up buddy set up. I have checked all the fuses and they are fine. I have it hooked up through a relay using the 12v on the trailer plug as constant power with the reverse terminal as the signal line. When I shift into reverse I can hear the relay turn on but with only 1.5v from the power the lights won't turn on.


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## Triple L (Nov 1, 2005)

Just use the reverse and don't worry about it... I have had 2 large non led lights hooked onto myn since 2009, are you worried about burning something up?


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## 1olddogtwo (Aug 6, 2007)

G.Landscape;1565378 said:


> OK....so I have basically built my own back up buddy set up. I have checked all the fuses and they are fine. I have it hooked up through a relay using the 12v on the trailer plug as constant power with the reverse terminal as the signal line. When I shift into reverse I can hear the relay turn on but with only 1.5v from the power the lights won't turn on.


sounds like your tapped into the brake wire.


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## G.Landscape (Oct 20, 2011)

Triple L;1565436 said:


> Just use the reverse and don't worry about it... I have had 2 large non led lights hooked onto myn since 2009, are you worried about burning something up?


Are you using a relay or just straight wired on? it seems when I try the reverse terminal that the fuse keeps blowing, so something isn't right. These are 2 spot lights at 80w each so they take a good amount of power.


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## Triple L (Nov 1, 2005)

G.Landscape;1565469 said:


> Are you using a relay or just straight wired on? it seems when I try the reverse terminal that the fuse keeps blowing, so something isn't right. These are 2 spot lights at 80w each so they take a good amount of power.


Striaght wired to the reverse plug with a trailer plug... 2 lights with 2 bulbs each light, very bright, never have had a issue


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## 1olddogtwo (Aug 6, 2007)

That's only 7 amps each


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## G.Landscape (Oct 20, 2011)

So I had 20amp fuses and they were still blowing. Changed the lights out to 2 50w bulbs and it workes fine now. Still wired through the relay but running off the reverse plug only


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## G.Landscape (Oct 20, 2011)

OK, so I realized the relay is doing nothing now to I took it off. Works good now. Thanks for the help. Here is what I mocked up, I used wood so when I back into something I can replace it instead of having a bend up piece of metal. Also used all the same color wire so if someone steals it they will be really confused.









Just kidding. I am going to make a proper metal box for it at the shop next week, this was just the **** I had lying around the house.


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## Triple L (Nov 1, 2005)

is that your truck?


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## Triple L (Nov 1, 2005)

myn is a 1 wire set up haha, You like complicating things I must say....


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## G.Landscape (Oct 20, 2011)

Triple L;1565522 said:


> myn is a 1 wire set up haha, You like complicating things I must say....


How are you going to get away with less wires then that? 2 Power and 2 ground. and yes that's my truck.


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## theholycow (Nov 29, 2002)

G.Landscape;1565526 said:


> How are you going to get away with less wires then that? 2 Power and 2 ground. and yes that's my truck.


Just for backup lights?

I mounted mine to my spring mounts, grounded them nearby, ran the two power wires into a Y-wire, then tapped that wire directly into my trailer harness's reverse wire. 55W bulbs in them, never blew a fuse. Couldn't see them without ducking your head under the truck but they lit up the snow behind me just fine.


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## G.Landscape (Oct 20, 2011)

theholycow;1565569 said:


> Just for backup lights?
> 
> I mounted mine to my spring mounts, grounded them nearby, ran the two power wires into a Y-wire, then tapped that wire directly into my trailer harness's reverse wire. 55W bulbs in them, never blew a fuse. Couldn't see them without ducking your head under the truck but they lit up the snow behind me just fine.


I figured it was best the ground right to the trailer plug instead of having another splice/ground screw to rust and fail. If it was any kind of distance from the plug I probably would have grounded right to the truck, I will head out and grab some pictures soon, just getting dark now.


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## G.Landscape (Oct 20, 2011)

Here is the lights. The fence is approx 130' (40m) from the truck


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## Triple L (Nov 1, 2005)

Exactly how theholycow said... Keep it simple stupid, soo much easier and I dig the clean look most of all...


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## CENTRALIAPLOWER (Dec 25, 2011)

*LED lights*

I used these lights for back up lights on back of my truck. As you all know LED lights draw very little amps so the can be wired right off the trailer plug reverse wire without losing output like u would a non LED light if a relay wasnt used. Used a sealed plastic box from radio shack and mounted on back all the wires.


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## Hysert (Dec 16, 2009)

center pin on seven prong is back up should power those lights no prob I have 2 on the spreader running off that and the third brake light all running off the bumper. my stock back ups have the hid aways in them and replace in the summer. took the top amber signal out of the front lights and mounted the hid aways in there too peaks out nicely under the western night hawks.


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