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Hi : I want to change my interior cap light so I can turn it on with out the key in. where is the closes power wire or so called hot wire. That I can tap into and will give me power with out truck key on. The only place I know should work is run a wire all the way to the battery and put fuse in line. There has got to be a better way.
Working with 2005 Supper Duty 6.0 Crew Cab long box.
If you want hot all the time, then the battery is going to be your best choice. If you have map lights in top the rear of the cab, you could intercept the hot wire for those, but it means drilling a hole in the rear of the cab somewhere.
What circuit is it hooked to now, do you know?
The only source of 12v keyed power to the bed area (that I can think of) is for the trailer tow plug. If that's what it's hooked to, you could jumper the relay and have it hot all the time.
Sure don't want to doubt anyone, but I'm pretty sure that the black wire on a 7 pole round plug is constant hot as long as you have the relay and fuse in place. I use it quite often setting up my camper. I power the slide out and interior lights with the truck until I get other power set up. I know the key is off as key to trailer hitch lock pin is on my key ring.
I have a Leer top and I tapped the +12vdc supply to the left rear running (parking) light, all you have to do is remove the tail light lens assembly to get to the wires, plus it almost eliminates the possibility of draining the battery due to the light being left on.