I know this was old but for anyone reading this the trailer brake can be matched with an up fitter switch I got mine for 105$ on ebay with the harness and fuse blockmy 06 6 0 doesn't have the upfitter swiches because i have the factory trailer brake system so i guess i need to install a rocker switch with a 12v power source connected to the proper wire?
I believe they are talking about using it "on demand". I think they all do it for extended idle at cold temps. I was actually thinking the same as you at first.From this post, it seems like the high idle is not standard on these trucks. I have a 2005 6.0, and it acts just like my old 7.3 did. After about 2-3 minutes at normal idle, it kicks it up to 1100RPM or so, until I touch the brake. Now I am not the original owner, so maybe something was modded, but I also have no upfitter switches, or additional switches anywhere, nor do I ever use the parking brake.
Did something get changed along the way to where this became standard? Perhaps a computer upgrade from Ford?