An infusion pump apparatus including a pain controlled analgesic (“PCA”) input device is disclosed. The infusion pump apparatus includes a housing, a pump actuator supported by the housing, and a PCA input device. The infusion pump apparatus also includes electronics configured to control the pump actuator, provide a voltage to the PCA input device, and sense an electrical signal in response to the pain controlled analgesic input device being depressed. The infusion pump apparatus further includes a controller electrically coupled to the electronics and programmed to determine whether the sensed electrical signal is discontinuous, and if the sensed signal is discontinuous, transmit an output indicative of the pain controlled analgesic input device functioning improperly.