Empty Fuse Slots

I'm wiring up some extra lights and am trying to figure out the best way to tie into power. I see there are a few empty fuse slots in both the in cab and engine bay fuse blocks. I haven't really been able to find a clear answer to what those are for and if they are hot all the time or just when the truck is on. I have seen where folks have tied into them with an add a fuse though. I'm assuming they are just for accessories I don't have. Anyone know what they are for and when they are hot, or can point me to a thread on here with that info? I did a couple searches but couldn't find what I wanted.

 

Use a test light to figure out if they are hot w/key on or off. If you're going to be doing any kind of wiring you should really own a test light

 

It got broken when I moved and this is the first wiring I have done since. Was being lazy and hoping to use the existing knowledge pool so I didn't have to go to the store.

 

Well at least you're honest. But the top slot is hot with key on I believe.

 

If you have some stuff laying around you could make a test light with a nail, wire, 12v bulb, roach clip, soldering gun. But that might be more work than going to go buy one.

Or if you have a multimeter, you could use that instead of a test light, I’ve been doing it for years.

 

The "PWR OUTLET" w/ 15 amp fuse in the top right is constantly hot when the key is removed. I added some interior led lights in the footwell and powered them with an add-a-fuse to that slot.

If I recall, the "DR LCK" is constantly hot as well, but I opted to use the other slot for my project.

 

Question: If you use any of the window fuse slots with an AAF, does that accessory turn off when you press in the window lock button on the driver door?

 

negative