Transmission lines play a primary role in power distribution and communication. Manufacturing or assembly mistakes, external constraints or normal functioning can create different types of defects inside cables, which can lead to catastrophic consequences. In this paper, we propose a novel method for the diagnosis of a complex wire network, including multiple subnetworks, to detect and identify hard faults and connection inversion based on pulse excitation signals. The method can detect multiple errors with a maximum of one error per subnetwork and is suitable even for very short cables. Furthermore, we introduce a method to optimize the used excitation signals so that the longest distance can be considered, and the signal can be realized at low frequencies by low-cost embedded systems using standard circuit elements. The proposed method does not need analog-to-digital converters since it requires only two-level signals nor high-frequency components since it does not rely on the signal's propagation time like classical methods. The efficiency is proved by simulation results on a complex wire network, including seven subnetworks with 20 ports and four defects.