A system for controlling power to actuators. For example, a controller may output a signal having a variable duty cycle waveform for controlling current to an actuator via an interface circuit between the controller and the actuator. Changing the duty cycle may change the amount of current to the actuator. The controller may provide a control signal that optimizes power consumption by the actuator for efficiency purposes. However, if the controller fails, then no control signal may be available to allow current to the actuator, particularly in situations where the actuator may need to be operationally tested. To avoid such situations, fail-safe bypass switching may be incorporated into the interface circuit. Upon absence of a control signal from the controller, the circuit may provide a default signal in lieu of the control signal to maintain current to the actuator.