A new diagnosis method for analog circuits-tearing method is presented. Anindirect measurement terminal equation is developed. The subcircuit terminal is said to be measurable if m≥m2

and the faulty branch’s parameter is said to be calculable if m = b1+l. Several techniques and formulas for fault location are proposed based on consideration of the tolerances of the nonfaulty elements. This method is capable of fault diagnosis in parallel branches at a single test frequency. Fault diagnosis in ladder circuits are also discussed.