A method and system for performing integrated adjustable short-haul/long-haul time domain reflectometry (TDR). A TDR pulse count is set to a predetermined number. Next, a TDR pulse is transmitted through a cable. The width of the TDR pulse is a function of the multiplication of the TDR pulse count with the period of a TDR clock. It is then determined whether the TDR pulse has been reflected back. If the TDR pulse has not been reflected, the TDR pulse count is successively increased to successively increase the width of the transmitted TDR pulse until a reflection is detected—indicating an open in the cable. Furthermore, it eliminates false detections of cable opens. Moreover, the system can be combined into a line interface unit (LIU) integrated circuit such that TDR functionality can be performed automatically without the use of a technician.