What is the easiest way to tap into a keyed 12V supply for a wireless air bag controll system? If I use the inside cab fuse box I have to get the wire inside the cab and then the fuse box cover may not fit back on. Isn't there a keyed 12V wire in the trailer harness I could tap into?
Would this be the preferred method?
Thanks in advance for any help.
Love the forum it helped me on the purchase of my 2012 F-350 Crew cab Dually "King Ranch"

 

I doubt this is the best place, but it is available at the radio. Seems that might overload the radio fuse, though.

 

I just installed a wireless compressor system and used a fuse tap on the rear window defogger fuse in the under-hood fuse box. It is a switched fuse. I was able to run the wire out of the fuse box with minimal modification to the cover because there is quite a bit of room under it.

I found that the fuses in the cab fuse box are low profile so they aren't good for using fuse taps.

 

Same as Ridin'High. Run it to the engine compartment fuse. Much easier and better since the fuses are bigger. I have my wireless compressor and my HAM radio pigtailed off the fuse (not sure if it's the same, since I don't have rear window defrost, but it is a switched 12v).