making/finding acc wire in new vehicles

yesterday i installed head rest dvd's in a 2010 silverado. most of these newer vehicles dont use the high power ignition wires the older vehicles had, atleast not at the ignition switch and i had trouble finding a good solid acc wire to tap. eventually after searching some forums someone said the brown wire in the green plug on the side of the fuse box would work as acc but i didnt want to pull power directly from it because it was probably a 20awg wire and there was no clear explanation as to what it controlled. i used this wire to trigger a relay and powered the screens from that. however, i would like to know if this was the best way to do it or is there a good acc wire under there somewhere? and what about other newer vehicles with the same sort of configuration? whats the best way to go about this in the future?

because of the lan there is no more high current acc. or ign . Just find one and relay it just like you did.

if it was for something small like a radar detector then you can hook directly

great! anyone want to second this? or offer another solution?

I'll second it. I always run a relay triggered by the low current accessory wire and powered by a good 12v power source.

Having the same problems with Euro cars, on BMWs and Minis there's a unit feeding from the push ignition switch, purple primary, Mercedes we use the cig lighter feed. The first poster is quite correct in what was done.