Towing Issues: GMC Savana Trailer Power, gmc savana, amp fuses

Question
I have an '04 GMC Savana 1500 AWD.  This came from the factory with a 7 wire pigtail at the back end for a trailer connection.  I wired the 7 blade RV connector on, but get no power to the 12V accessory power at the trailer.  I have checked the fuse box.  There are two 30 amp fuses listed as "trailer" and they are both present and good.  There is one large ring lug next to the underhood fuse box that is hanging in space.  I tried putting a meter between it and ground and I got nothing, so I am not sure it is even related.

Any ideas as to what to do to get the power flowing back there would be helpful.

Answer
You need to find the wire at the back of the vehicle for accessory power, and confirm it has no power.  then see if you can trace it back to the fuse block or under the dash.

Try seeing if there is continuity between that loose lug and the power wire at the back.  If so, just bolt it up to one of those 30 amp connections under the hood.  

Here is a wiring diagram page that might help.

http://www.marksrv.com/wiring.htm

Don