Shorts to Ground
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
Measure the harness resistance between the suspect circuit at the harness connector and a reliable ground (B-, chassis gnd or PWR GND at the PCM breakout box, if available). The resistance must be greater than 10,000 ohms.