Pinpoint Test E: DTC B1681 - PATS Transceiver Module Signal Is Not Received: Notes
WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
Refer to appropriate SYSTEM WIRING DIAGRAMS article, Passive Anti-Theft System for schematic and connector information.