A device is equipped with an electrical connector in the form of a receptacle that is subject to liquid intrusion. The device detects the insertion of a mating connector and optionally detects the presence of liquid in the receptacle by applying a low power, pulsed sense signal to a terminal pin of the receptacle while the terminal pin is decoupled from a circuit part to which the terminal pin is normally coupled and concurrently sensing a voltage coupled from the terminal pin and comparing the voltage to at least a predetermined lower voltage bound and optionally a predetermined upper voltage bound and based on the results of those comparison deduces the presence of a mating connector or optionally the presence of liquid in the receptacle.