Power Lead?
 

Im looking to hard wire my gps unit back into my 08 f150, after finding out that having it steal power from the brake controller harness was making the controller screw up. Anyone know where i can find a hot wire to tap into thats relativly easy to find under the drivers side? Id rather not have to dick around with cutting a hole through the firewall to run a lead from the battery. any insite would be helpful.

Look through here. Theres a few hot wires in there.
2008 ford f 150 wiring

the back of the cigarette lighter is an easy place to tap into with a y-adaptor. Good luck.