Question Wiring question GMC 2003 2500HD

[partsman01]

So bought this GMC and it has a 7 pin plug under rear bumper, previous owner never had a brake controller installed, so have no idea if he ever used it, but also found a wire harness by drivers side between cab and box, I will add pics, but my question is, if I can plug my fifth wheel into it will it power everything, and if I buy a brake controller and harness that is plug and play, will it then have brakes?
And the same with what is on the drivers side, are they wired in so that all power is there and with just the addition of a brake controller will there be power to brakes?
And of course, what controller should I buy?
Any part numbers for it and the harness?
Thanks
Here I hope are the pictures.

[0rion]

I run the P2 in mine and love it.....good brake controller.

[partsman01]

Well bought the prodigy 2 controller, with the plug and play harness, had wanted the prodigy 3 but turns out they only had the prodigy 2 so took it, have to mount it, and have to get the fuse that plugs into the #1 stud spot, then I will hook it up and see what is up, truck is not insured yet as I am still trying to get the hitch install finished, then we wont be going away till July, so not sure if I will even get a chance to test it all, but for sure it will get used in summer for a week.
Looks to be a nice controller and guys at work with them like them, they figure the prodigy 3 was not needed for my use.

[0rion]

If you take that harness out of the loom it'll reach to the back of the truck and you can mount it on the inside of the bed right by the tailgate. Just pull the brake light out, drill a hole, and mount the connector there. I learned about it reaching after I had already bought wire and soldered it onto the harness to extend it back there. That bundle behind the cab actually originates from the rear.

[partsman01]

Well working on installing my old Hijacker SL24 hitch, of course it just had to be awkward, once side is above fuel tank, the other is right above heat shield that seems to run length of the box, broke a bit trying to undo it as it looked to be a torx, anyway, am going to use a hole saw to cut just a hole to access the bolt to put washer and nut on, not like one video where they sliced the heat shield right out, I think the hole saw will be a better idea.
But the kit I got 8553004 only comes with stuff for bolting to frame, not for installing the rails, so instead of the hex head bolts they call for, I am using carriage bolts, and so they go through rail, through box then underneath through bracket, then I will put a regular 1/2" washer and then a 1/2" nylok nut on, don't imagine I need anything else, they do not supply any spacers, so I guess they do not worry about the box crushing down.
Fun job, but rather pay myself to do it.

[partsman01]

Great link, thanks for the help

[shadoow]

this link may help. It's a pdf download describing electrical information for 2003 and later chev/gmc trucks

[Me_Again]

There might be two wires under the hook that have never been connected. One between the drivers front fender and battery is for the trailer charge lead I believe and the other is down by the steering column and is the brake controller power lead!

Chris

[donn0128]

Yea, early GM products had two connection points. Rear bumper and a place at the front of the box for camper/fifth wheel plug in. Brake controllers are sort of a personal thing, but most people really preferr the Prodigy controller. Buy that and also get the prodigy pig tail. Makes for a quick simple plug and play. You will also need a 60A (I think) fuse to replace the dummy fuse in the under hood fuse panel to power the battery charge line.