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Constant 12v Power to 7pin Trailer

HOFFandGOLDMAN
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HOFFandGOLDMAN Enthusiast

HOFFandGOLDMAN

Posted
Posted

Does anyone know how to hook up the 12v constant power to the run lights in my trailer? They definitely work on our dodge 3500, but on my 2014 Sierra 1500 they don't.

 

My only assumption is its not hooked up from the factory. Is it as simple as the older model GM trucks? Hook up a wire to the post by the fuse box and plug in a fuse for that location?

 

Cheers

Jay P Enthusiast

Jay P

Posted
Posted (edited)

There is a fuse in the under hood fuse block for the trailer battery power. I think it's fuse #2. It's not normally installed from the factory. In all my previous trucks all I had to do was install the fuse to send power to trailer battery.

 

Jay

Edited by Jay P
crankman Enthusiast

crankman

Posted
Posted

Look right behind the fuse box under the hood there is some black wire loom and mine was taped to it with black electrical tape. Then i uncoiled it ran it to one of the unused fused posts. Then install a fuse and it should send power back there .

  • 1 month later...
Rock1500 Senior Enthusiast

Rock1500

Posted
Posted

Look right behind the fuse box under the hood there is some black wire loom and mine was taped to it with black electrical tape. Then i uncoiled it ran it to one of the unused fused posts. Then install a fuse and it should send power back there .

 

By any chance can i get a pic to see what you speak of? I have a fuse in the #2 spot already but don't see any black wire loom or sorts.

  • 1 year later...
  • 7 months later...
Kubs Enthusiast

Kubs

Posted
Posted

Bringing this back up. Anyone have a picture? Or a diagram from GM?

  • 3 weeks later...
Kubs Enthusiast

Kubs

Posted
Posted

Turns out mine does charge from the factory.  I didn't have to change anything.  I have an NHT Max Trailering equipped truck though.  Maybe those without NHT you have to hook something up.

  • Like 1
  • 2 years later...
Teutonics Enthusiast

Teutonics

Posted
Posted

Anyone have any updates on this?  I have the fuse in the #2 spot, but no power to the fuse.  I don't find any wiring taped up to the loom.  

 

Has anyone been successful with this?

swathdiver Senior Enthusiast

swathdiver

Posted
Posted
50 minutes ago, Teutonics said:

Anyone have any updates on this?  I have the fuse in the #2 spot, but no power to the fuse.  I don't find any wiring taped up to the loom.  

 

Has anyone been successful with this?

https://www.gmupfitter.com/files/media/photo/836/18_Sierra_Body_Builder_2017AUG31.pdf

 

Seems to me that it is already wired up, I searched "Trailer auxiliary".

Teutonics Enthusiast

Teutonics

Posted
Posted
On 10/24/2020 at 5:45 PM, swathdiver said:

https://www.gmupfitter.com/files/media/photo/836/18_Sierra_Body_Builder_2017AUG31.pdf

 

Seems to me that it is already wired up, I searched "Trailer auxiliary".

Thanks for this.  I removed and reseated the ECM and it's working now... must have been some corrosion or some other poor connection.  So yes to confirm, this is connected from the factory on the K2XX models.

 

Thanks!

  • Like 1
  • 3 weeks later...
Ravenkeeper Senior Enthusiast

Ravenkeeper

Posted
Posted
On 11/12/2020 at 1:37 PM, Chewwie said:

Does the 12V trailer pin get power with the key in run,  run and accessary, or all the time?

All the time.  We had a trailer, at work, that the tail lights and the 12V were crossed at the plug.  As soon as we plugged in, all of the lights (tails/corner markers) would come on, and we'd have to turn on the truck's lights to charge the trailer battery.

  • 1 year later...
mwharlan New Member

mwharlan

Posted
Posted

My 2017 High Country HD is prewired. Nothing to do.  If you have power to Fuse 2 under the hood, then you should have power on the B+ terminal all the time.  I found that corrosion had gotten into the wiring harness on the other side of the plug.  My truck has an accessory wiring harness (part #84154213).  Replaced the harness and plug.  All is good.  You can opt out of the harness if you want.

 

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