Abstract: A system for extending a vehicular alarm system includes a base unit and a remote unit. The system is configured to extend the vehicular alarm system to an accessory or equipment secured to, carried by (e.g., outside or inside) or in proximity to an automobile and/or to equipment secured to the accessory. The base unit is configured to be carried by the automobile and to communicate with the vehicular alarm system. The base unit may be configured to mimic activation of a sensor of the vehicular alarm system in a manner that can activate the vehicular alarm system. The remote unit is configured to be carried by the accessory, and may sense removal of the accessory from the automobile, opening of the accessory and/or removal of equipment from the accessory. Methods for extending a vehicular alarm system to operate with one or more accessories are also disclosed, as are methods for detecting and providing an alarm when an accessory or equipment secured by the accessory is undesirably disturbed.