A technique for identifying lead-related conditions, such as insulation breaches and/or externalization of lead conductors, includes analyzing characteristics of electrical signals generated on one or more electrode sensing vectors of the lead by a test signal to determine whether a lead-related condition exists. The characteristics of the electrical signals induced on the lead by the test signal may be significantly different on a lead having an insulation breach or externalized conductor than on a lead not having such lead-related conditions. As such, the implantable medical device may be subject to a known test signal and analyze the signals on the lead to detect lead-related conditions.