A brake controller for controlling the brakes of a towed vehicle which is pulled by a towing vehicle comprises a sensor assembly which determines the position of the brake pedal of the towing vehicle, and if necessary, compensates for inertia which can affect the output of some sensors. The output of the sensor assembly is transmitted to a processor, which in turn transmits a signal (the strength of which is a function of the pedal position) to brakes of the towed vehicle to activate the brakes of the towed vehicle.