IF they are aftermarket, then it's anyone's guess. I would start with the obvious. The top one looks to have power from the battery? My guess would be the lift or the aftermarket A/C. I would play around with the different accessories with the ignition over on run and listen for the relays to switch when a button is pushed or switch thrown.
I figured out that the top one is the relay for the interior lights, I'm still learning about the basics of automotive electronics.. the other two, I'm still not sure about, one of them went to a switch that sent power to the motorized step I removed. I cant get them to trip however... I guess I'll mess with them later...
I'd highly recommend either putting vapor barrier over that fiberglass insulation or switching to something that won't absorb moisture. You give off a lot moisture just breathing and cooking in the van will add a lot more. be sure you treat any interior rust issues as you go or they will get worse after you start sleeping in it.
Thanks for the tip, I honestly hadn't considered the chance of the insulation absorbing moisture, I realized after reinstalling all the interior panels, that I'm going to have to remove them again to run some electrical wiring and some plumbing... When I pull it all out, I'll put each piece of insulation inside a heavy duty trash bag, whamo, moisture barrier insulation....
