What sure would be nice to have is a definitive guide to these 12V pre-wired connections. Pg 453 of the manual provides only a bit of insight with regards to how/when they are hot.
For example, I just walked out and tried my bed lights; nothing. Then I started the Mav (from inside the truck...
One thing I noticed is that the 12V connection is a bit funky with regards to when it is hot. Try starting the truck, turning it off and then checking if the lights work. I too swapped the fuse but it turned out the real issue is re: when the bed port is actually on.
Jumping in here to rant about Seal Skin covers; please save your money and do not purchase from them. So many issues after just six months:
They mention that their products are waterproof -- however, my cover every morning is damp (it's been nothing but blue skies for months here in Northern...