Ok first I have a 03 2500 4x2 with the CTD. I bought a prodigy controller with factory pig tail for quick hook up. All went well with this part. So I get to looking for the wire harness at the tail end of the truck. I find a 4 pin connector. Of course I need a 7 pin hook up. So I go to dodge and buy a $73.00 wire harness with all connectors. one connector is the seven pin itself and one goes to the 4 pin. A black wire has to be tied into the left tail light black wire. Connected the ground wire to the frame. Done this and then routed the rest of the harness to the front of the truck. One wire bolts to the battery terminal and has a fuse in it. Now comes the confusing part. There is a blue wire left over. It is the trailer brake wire and since I have my controller already plugged into the provided connector under the dash where and how do I connect the blue trailer brake wire? Am I missing something here? Help.

 

the blue is your electric brake wire

 

If you do a search, one of the previous threads, months ago told where the wire terminates from the main harness. I think that it was between the drivers door and the front wheel. You would splice the blue wire to that wire to complete the circuit. If that is a problem to find, just run the blue wire into the cab and splice it to the harness at that point. Just so it connects to the controller it will work.

Thumper he has a truck without the towing package. The plug is under the dash but the blue wire ends somewhere outside the cab.

 

I guess I am not understanding your plight at all!! If you have a factory tow harness all you should have to do is plug it in!!!
Now I think prodigy says they want you to run a bigger pwr wire (black) cause the stock one is too small for amps-right??
The white dose go to grd. but for best results take it all the way to batt.grd...........agan if you have a factory harness there thats not nessary.
Or mabe try me agan ,maybe I do no t get it????

 

Ok, I found the blue wire (Brake wire). It terminates under the cab just aft of the left wheel well. Tied into it and no more problems with that. I have another issue I will post under a new thread.

 

Thumper I though I read it right, he was installing the factory harness the truck did not come with it. That's why the confusion.