I assume there would need to be some sort of voltage regulator.
The FJ is 12 volt, USB is only 5V (I think).
I bet you could get one of those things that plug into your cig lighter and has USB ports on the other end, rip it apart, and use the 'guts'.
I did a quick google search for a 12V to USB adapter, but most of what I got were the plug in type.
I'm no electrical engineer, BTW... :bigthumb: