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'05 Sierra brake controller and trailer plug problems

7K views 7 replies 3 participants last post by  Machster69 
#1 ·
Hi all,

Have a problem in a couple areas after hooking up my brake controller and rear trailer harness.

First off its a 2005 GMC Sierra 1500 reg cab long box 2wd 4.3 automatic.

After installing a Curt hitch, Curt Venturer brake controller and a Hopkins 7 pin plug on the truck I hooked my truck up to a few different trailers and the brake controller didn't light up or even work manually. These are 20' tilt beds, 12' dump and a 20' deckover and they all work on the other trucks in the yard. I made sure there was a 40 amp female maxi fuse in stud #1 and the red wire was connected and still nothing. I tried another brand new Curt Venturer controller with the same results. Am I missing something? I will test the wires out of the fuse block to the controller tonight and give the outcome.

Next issue is the Hopkins trailer plug is the simple plug in to factory harness style and has the 4 wire flat plug alongside the 7 pin round plug. When I tow my smaller trailers with the flat plug the lights work fine but if I use a 7 to 4 adapter nothing works. Tried with multiple trailers and 7 to 4 adapters with the same results. Now if I plug a larger trailer with brakes and a 7 pin plug all the lights work fine, just not the brakes which could be related to the first problem. I will be checking power at these wires tonight also. I have another plug on order and will try that also.

Now before anyone says I shouldn't tow that big of a trailer with the truck set up I have, I will agree, but I do tow a small trailer with brakes and a small mud buggy that I wouldn't even need brakes on a trailer for, but I like to be cautious and have the extra safety of extra brakes helping me slow down. I don't tow the bigger trailers with my truck just used them as a test tool.

Thanks for any help or direction anyone can give.
 
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#3 ·
I was under the impression I just needed to plug into the fuse box under the dash with the brake controller, no wire splicing needed and same with the rear trailer wiring, just plug into factory harness and all is good, no splicing and dicing required.

Am I wrong about that? Is there more to the trailer towing package when installed from the factory/dealer that my truck wouldn't have since it didn't have the tow package feature? If it takes just running all needed wires to make it work is no big deal, I've installed them that way before, was just hoping for the easy plug and go like on our 2500's and 3500's
 
#6 ·
I checked out gmupfitter and from what I glanced at I needed to wire the truck to adapt the controller and rear harness. The ones I bought simply plugged into existing pigtails and slot in the fuse panel on the truck just like our 2500 and 3500 with no extra wiring. I guess my question would be did these trucks come wired for these since the pigtails are already there or do I have to splice and run wires also? or is it a case of just cause its there, don't mean it was meant to work? Or might it need a reprogram like some do for the foglight upgrades?

I will do a bit deeper reading on it there because I also want to wire up my yellow rotator to a factory style switch and relay system like they show on their site.

I've pretty much scratched the whole idea of the 7 pin and brake controller on this truck and am looking at a deal on another bigger truck to do my towing, but curiosity has gotten me on this one now so I kinda wanna find out why it doesn't work as easily as I hoped.
 
#7 ·
Ok did a little more reading at gmupfitter and it looks like I would need to run the dark blue wire from the controller to the rear harness so when I get a free minute I'll have to run a wire back and see what that does for me.

Thanks for the link to get me in the right direction.
 
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