To obtain a secured mating of electric connectors is one of the most important steps in a robotic wiring harness assembly system. Although there are plentiful results about complex peg-in-hole assembly problems, little work has been done with respect to this special issue. In many cases, mating connectors can be regarded as a hole search process of a multiple hole-in-peg problem. Because various faults might occur during the search, a reliable error recovery strategy is necessary in the mating task. In the paper, the error detection algorithm and the error recovery algorithm for various connectors are mainly realized by using force/torque sensor. The experiment results show the proposed system can detect and diagnose the position errors, and realize error recovery and mating successfully. It shows the fault-tolerable capability of the system is improved evidently.