WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Horn Cigar Lighter Circuit Diagram (1 Of 2)
Courtesy of FORD MOTOR CO.
Fig 2: Horn Cigar Lighter Circuit Diagram (2 Of 2)