If you really want to run accessories in an AD truck, use a switch and run from the always hot on the ignition switch. How ever, if you don't turn it off when you park, you will have a dead battery. Only circuit I have contemplated doing this to my truck is the turn signal switch. Mine has a hazard flasher position that I might want to use with the truck off. Just a safety thing, my E brake is a little soft. New cables and adjusted but soft. I think the cables have some stretch in them. So if I stop to help some one I have to choose, let the truck run, lights flashing? Or truck off, no rolling.
