I Have A New 4500 And It Did Not Come With The Plug For The Trailer Brake Controller Like My 3500. I Looked Under The Dash And There Is Not A Port For The Plug Like The 3500. There Is A Totally Different Round Plug That Looks Like It May Work. Where Do I Get This Plug Assuming That It Is This Round Plug.

Can't answer that question, but when "they" fitted the prodigy to my truck, they had to wire it in the old fashioned way..

Mylash

Go to www.gmupfitter.com look at the files for wiring on my 2003 the blue brake wire is in a bundle behind pass frount tire the rest of the wire are in the body builders harness on the frame behind the cab on the pass. side a pigtail cost about $116.00 to fit that plug from gm. upfitter will give hours of reading and help you to find out almost anything about your truck .Good Luck tell us how you make out.

The round plug may not work. Saw the plug on my Kodiak too. I have a Drawtite control but it is not plugged into the round plug. Don't know what the round plug is for. John

The round thing is the diagnosic connector for the CAN communications. Nothing to do with brakes. I actually am involved in the engineering for this truck, and I think that trailer brakes is an option. I am not a brake guy though. I will try and find out more.

I have an answer to your question. The trailer harness option is U86. If you have this you have a trailer connector on the back of your frame. All of the wires are used except for one, this is the trailer brake wire. It runs up the chassis harness into a large white connector on the passenger side of the frame. It comes out of the other side of that connector and stops. This is where you have to tap into it. Peel back the conduit between the white connecor and the front of the truck. You will see the wire cut off there.

HMMMMMMM...I found my brake control wire on the Pass side under the computer trays.

Pull the pass fender liner out & look under the computer trays where you see all the conduit comming up from the frame. Look for a blue wire sticking out of one of the counduits thats the wire your looking for.
Far as wiring up the brake control box get a simple wire kit from your local auto parts store and your set!!!!!!!!