This paper explains about one of the crucial problems that can be faced in an electric vehicle. Brake ineffectiveness that is brake system failure can occur due to different possible reasons that are mentioned below in the paper. To solve this problem we have considered data of 560 vehicles. Vehicles brake oil was manually filled earlier which it has consumed almost 15 minutes in production line, whereas the machine can fill the oil by removing the entrapped air in the system through creating vacuum in just 5 minutes. The results show the 3 times improvement in the production rate of an electric vehicle industry after solving the root-cause and making it completely automatic. Different methods of approach like torque test and vacuum drop test were performed on the brake system to identify the root-cause of the problem. The approach towards the problem has involved in detail design analysis which helped in identification of the root-cause. Hydraulic brake systems have unique oil of different grades they are dot 3, dot 4 and dot 5 or dot 5.1. The chemical composition of the fluids also changes according to their classifications. Here we used DOT 3 oil as brake oil, and performed the analysis.