Check the photos in post 19 of this thread. The blue plug is where it should plug into.

 

What is the one below the blue one for...I had a pic posted but needed the room for another one now I can't find the original, There is an empty grey plug below the blue one does anyone know what that is for, possible an amp? That is where the amp bolts in somewhere near there?

 

I wanted to be able to reach all the adjustments and see the warning very clearly.

I just used some industrial velcro on the mounting bracket and the top of the radio bezel. In the past I've just used a heat gun to remove it. This prodigy controller is by far the best I've ever used.

 

After much reading and searching - I was misled, and you most likely are too if your trying to find the "BLUE" wire that leads to the electronic brake controller.

It isn't blue - it's green. If you have a 4 - pole flat pre-wired by mfg. Then make life simple, no matter if you buy a Hoyle or Reese electronic brake connect, get the Hoyle connector (it connects directly to the 4 pole, long flat, connector under the dashboard by the parking brake to the left of the junction box), but if you buy the Reese electronic connector you'll have to clip the plastic clip off that would connect to the Hoyle brake controller so you can wire the Reese to it.

If you have 4 pole flat wire installed like I did, then the GREEN wire will stop at a connection just behind the mudflap, in the driver side front fender well. I used a wire clip, tied in, and ran it to the back inside the same cable channel that carries the other wires on the driver side of the frame. It got a little tricky going over the fuel tank. But it's possible. On my truck is was just above my volt-meter probe. In the middle. Remember, trust but verify. Check yours voltage there while somebody depresses the peddle.