We propose to research, design, and develop active and passive signal and cable diagnostic capabilities for our Smart Universal Sensor Interface (SUSI). SUSI is designed to accommodate more sensors than conventional avionics sensor units, using fewer wires, less power, and at greater data rates and shorter delays, while consuming less physical space. In addition, SUSI provides advanced features such as: upgrades to optical avionics networks, full compatibility with legacy systems such as AATIS, CAIS, 1553, and ARINC; serial sensor buses to further reduce wire count; smart functions such as described in the IEEE 1451.2 standard; and extensive local processing and data storage capability. SUSI is designed to be modular to a very high degree - even the network interface can be changed by simply replacing the network module. These advanced features can be used to implement diagnostics and health monitoring functions for a wide range of applications, including wiring diagnostics. Since SUSI integrates into the avionics system and is designed to take data and control actuators, there is no added overhead (weight, cost, etc.) for additional instrumentation. This system could provide critical data not only for safety purposes but for maintenance as well, thus helping to extend useful aircraft life. Both military and commercial aircraft could benefit from advanced smart sensor systems capable of providing real-time data on subsystem health.