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Mookie Brown 06-08-2011 03:55 PM

GMC 7 Pin Wire Harness Problem
Anyone here know things about the GMC's electrical hook ups for trailers? I found this site helpful:

...but it didn't solve my problem. The boat trailer's got a surge brake actuator with a solenoid that kicks the brakes off for backing up. The solenoid is supposed to activate when the reverse lights are on. From what I can find, the reverse lights are controlled by the middle pin on my 7 pin harness. The problem is that although the truck reverse lights work, there is no power to the center pin on the truck's harness. I also went underneath to verify that the center pin is hooked up to the light green wire (per the etrailer site's instructions).

Then, I tested running lights and turn signals with the multimeter - both good, but reverse had nothing. Further, I checked the fuse under the hood and it was good - even swapped it with another to make sure. I'm running out of ideas! It's a 2007 Sierra, if anyone has any advice on how to further troubleshoot this thing.

Mookie Brown 06-08-2011 04:32 PM

Here's why I'm a power bottomed bitch:

After posting the above, I sat around the house pouting for a while. Then when that wasn't helping, I thought, 'why don't I pull the exterior housing of the harness out of the truck and have a look?' So, I did that. Turns out the center pin had been smashed down. It's probably been that way since it was assembled because it hasn't ever worked. After straightening it out and putting it all back together, what do you know? It worked like a charm.

So, this thread can be taken down to save space, or left up to make me look stupid. Either way, its cool.

blue avenger 06-08-2011 05:18 PM

wiring can be a pain, mine needs to be redone. corrosion and snow banks have taken there toll.

Gotmud 06-09-2011 07:07 AM

Corrosion is usually the cause inside the plug on a truck, I replace at least 1 a week due to corrosion or just broken wires. Glad you got it figured out.:thumbss:

OCR 06-09-2011 04:02 PM


Originally Posted by Mookie Brown (Post 114045)
Here's why I'm a power bottomed bitch:

So, this thread can be left up to make me look stupid. It's cool.


We'll leave it to make you look stupid!! :jerry:

DirtylilWolfess 06-09-2011 11:48 PM

Trailer hookups never work. I know your pain (stupidity) Mookster. :bitchdrama:

The cops have been plain old forgiving of my trailer light problems up until this morning.

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