I got this from THE DIESELPLACE FORUM , might help.......KENNY
Let's get the facts straight
1. We are talking about the new body style 07.5, 08, and 09 trucks, the old body style trucks are different
2. The wire to feed 12v power to the trailer connector is the one taped up to the harness under the master cylinder, you must connect it yourself and get your own metric nut to put on the stud.
3. That 12v power wire gets connected to stud #1 which is at the front of the under hood fuse box closest to the FENDER
4. If the truck is a diesel and has 2 batteries or is a gasser and has an extra battery installed from the factory the 40 amp fuse in position number 63 should already be installed, if it's not then put one in, if it's there make sure it's not blown.
5. The wire taped up between the under hood fuse box and fender is the power wire for an aftermarket brake controller and would get connected to stud #2 that is in front of the under hood fuse box and closest to the Engine, it is supplied power from fuse number 58 and is a 30 amp fuse. If you have the factory Integrated Brake Controller DO NOT connect this wire to anything.
6. There is already a wire connected to stud #2 which goes right into the wire harness in front of the fuse box, I'm not sure what it's for but I think it's the power wire for the Factory Integrated Brake Controller, maybe Heymccall can verify and if someone Doesn't have the IBC they can look and see if they have that wire hooked up. Either way leave that wire alone if it's there or not.
Now if you hooked up the wire's correctly and checked the fuses and have 12v at stud #1 but still don't have 12v power to the trailer connector then you most likely have a problem in the wiring somewhere, most likely at the trailer connector.
But there is a junction block or two under the bed of the truck that could be a problem too.
If your having problems with the trailer plug don't forget to double check the Camper wiring harness, if you have it, that should be taped up under the front of the bed or may be as far back as up on top of the spare tire. The wires are just cut blunt ends and have power to them just like the trailer connector and they maybe touching each other or touching ground and causing intermittent or constant problems.