Shorts to Power
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Ford RV Cutaway, 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.
Key ON to power up the circuit. Measure the voltage between the suspect circuit at the harness connector and a reliable ground. The voltage must be less than 0.2 volt.