The EOL (End of line) testing is generally performed at the end of the plant production line test bench to control the quality level. Each product must pass through the EOL test to compliance with the overall quality requirement. The ROTAS transmission testing bench can perform the gear tooth checking, manoeuvrability evaluation and the synchro ring detection. As the legislations push forwards, the OEMs put higher demands for the products. Also, from economic consideration, more imperfection detection has been required. Thus, some new defects detection method has been developed based on the acquired signal.