Trailer Tow
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
When the vehicle's rear stop/turn or parking lamps are illuminated, voltage is also supplied to a corresponding trailer tow relay (coil side) located in the Battery Junction Box (BJB).
Vehicles not equipped with trailer tow require a Ford authorized accessory kit, if this option is to be added. Adding bulbs/lighting to existing circuits can cause the SJB to shut down the circuit and set a DTC due to the unexpected current flow.