Abstract: An operating system for towed vehicle electric brakes where an electric signal proportional to the longitudinal force between a tow vehicle and a towed vehicle is used to create an output signal to actuate the brakes of the towed vehicle. The response of the output signal has a non-linear relationship to the difference between the instantaneous longitudinal force value and a target value. In the absence of a longitudinal force signal that fluctuates beyond a specified value from the target value, an alternative signal is created using predefined user values. A preferred embodiment includes a periodically increasing alternative signal with user settings for the rate of the periodic signal increase and for the maximum signal level.