Question here on some on truck side trailer wiring. I picked up a ’06 2500hd, gas rig, used. As you can see in the photo it has some loose wires heading into the trailer wiring receptacle by the trailer hitch. The light blue wire is pulled out of the trailer receptacle. I have not hooked this up to a trailer yet, to see what functions work and what does not. Anyone know what the light blue wire controls? I got rid of my big gooseneck when I sold the duramax, so have not hooked up to anything, just want to be ready incase I do hook up to a trailer.

At first glance, not sure how to fix it. Anyone have any ideas. Would be great if their was a plug and play to just replace this section of the wiring and the trailer receptacle. Any advice or putting me in the right direction would be helpful.

Thanks

Now that unplugs from the trailer plug. You may be able to get the pin out if you can figure out how it is locked in there. Then reconnect to the pin. Then before you attach the wire back slip some heat shrink tubing over the wire that is bear there unless it has broken wires within it.

Brian

I don't think the Lt Blue is connected to start with.
This may be the CHMSL wire. Page A-21

See Link below:
pages A-14 thru A-23
pages C-38 & C-39 (trailer connector)
pages D-179-D-181

http://www.gmupfitter.com/publicat/2004_BB/2003_Beyond_LD_Electric_CK.pdf

If its a seven wire plug here is the wiring diagram:


http://img34.imageshack.us/img34/8014/7waytrailerend.th.jpg (http://img34.imageshack.us/i/7waytrailerend.jpg/)

If its a seven wire plug here is the wiring diagram:


http://img34.imageshack.us/img34/8014/7waytrailerend.th.jpg (http://img34.imageshack.us/i/7waytrailerend.jpg/)

Your diagram above does not match page C-38 in the link I posted above.
I trust the info in my link.

The light blue wire is for a center mounted stop light-- if you add a camper. It is hot with the brake pedal, but not with the turn signals.

just went and looked at mine and it is the CHMSL,and its supposed to have an end on it. can you till if the truck had a cap on it? if it did then th ewire was used for the cap brake light

Here's what your Light Blue wire is supposed to look like:
http://www.dieselplace.com/forum/showthread.php?t=404650

Here's what your Light Blue wire is supposed to look like:
http://www.dieselplace.com/forum/showthread.php?t=404650

Good find!

Thanks all. The PO told me no cap on the truck so not sure why this wire was striped off … but I'm just going to go ahead and cap it, add a little heat shield and go, as I don’t plan on putting a cap nor a camper on the truck.

Once again DP came through. Question asked and answered.

Much appreciated.

your welcome