US Patent 7737576 Vehicle mounted accessory with multiplexing

A control for a vehicle mounted accessory that has an electrically operable device. The accessory is operated by a switch that is mounted on the vehicle remote from the accessory. The switch and the electrically operable device are electrically connected by programmable controllers and a communications bus. The control has the capability of automatically determining the presence of a vehicle DRL mode, and the accessory turn signal lights are automatically illuminated to provide an accessory DRL mode. The control can automatically detect different accessories and reprogram itself to control them. The control provides a secured communications link between it and the accessory to prevent accessory theft.