Enabling B+ on 7-wire trailer plug

I have a 2007 Savana that I ordered with the towing package. I cannot seem to get the auxiliary power or B+ at the 7 wire plug at the back of the van. Maxi fuse number 50 is present in the underhood fuse box. Is there something else I need to connect somewhere?

I am having the same issue on my 2004 Savana. I checked and fuses 13 and 50, both 30 amps and listed as Trailer in the manual, are present and good. If you find the solution to the problem somewhere else, could you please post it back here so I can benefit also.

I did notice that there is a wire with a large ring lug hanging free next to my underhood fusebox. I checked to see if there was 12 volts between it and the nearest post in the fusebox, but got nothing. When I get a chance I may check it for continuity to the trailer accessory wire in the back.