Principles of Operation
WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The trailer tow stop/turn lamps receive voltage from the vehicle rear stop/turn lamp circuits. When a rear stop/turn lamp is illuminated, voltage is also sent to the trailer tow connector.
The trailer tow parking lamps are supplied voltage by the trailer tow parking lamp relay. When the parking lamps are illuminated, voltage is also sent to the trailer tow parking lamp relay coil. When the trailer tow parking lamp relay is energized, voltage is routed to the trailer tow connector.
The trailer tow reversing lamp relay is supplied voltage from the reversing lamp circuit. When the reversing lamps are illuminated, voltage is supplied to the trailer tow connector.