CAN (+) Circuit Shorted To Ground
WARNING: This page is about a different car, the 2011 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.
Courtesy of FORD MOTOR CO.
In the event that the data (+) circuit becomes shorted to ground, both the data (+) and data (-) circuits are pulled low (0V) and all communication capabilities are lost.