There's no 12V power in that connector, you have a basic mirror, that connector is for the windshield temp and interior humidity sensor, leave it alone
I would hope people chime in, but I know there are guys who have switched to bilsteins. I'm considering it myself. Truck wags side to side too much over uneven roads.
Hopefully they fixed it even though after all of your time and issues they couldnt even use the proper service manual document. That doc# you referenced is information for harness chafing on the 2.7turbo. I imagine they found an issue with your harness about a foot and half from the ECM connectors where the engine harness runs over the alternator. That may be where your problem lies as well ullose272, it's been showing up on a few trucks.
Yup, if your trailer has a battery maintainer that keeps stable voltage on the same circuits that truck feeds with trailer pin E, then your trailer will keep your truck battery maintained.just be sure you don't have an isolation switch on the trailer that doesn't allow it to power that circuit to the truck.
If there is NO wire currently in the underhood fuse block you won't need to cut anything. If there IS a wire there, it's easier to cut the wire in the truck and splice that harness you are holding to the end that goes into block instead of removing the one that's there just to install another one
Doesn't the other end of the wire you are holding have a length of brown wire and the small terminal for inside the truck on the other end of it?
If it does NOT have a smaller terminal on the other end then Wire #13582297 is a preterminated lead that will plug into the body control computer brown plug X5 position 10 as stated in the instructions. You could then make your own harness.
There have been at least two different GM documents regarding this concern, both required engine control module software updates as remedies. Additionally as mentioned aftermarket 12v accessories left plugged in with vehicle off are known to cause concerns.
It's discussed in the "extended parking" section of owners manual as mentioned. Just buckle your seat belt, or try using one of the seat belt alarm silencers. They are literally just the male buckle portion of a seat belt and can be had for as little as $2.
The actual tool is J-38125-212. You could also make do with a paper clip or two dental type picks and some patience. Alternatively you could sever the existing circuit, and cut off the terminal in the fog light kit, the crimp the kit harness wire to the factory wire coming from the fuse block.