Modeling of an automation process for an electric cars production line using Petri Networks and GRAFCET with a shared resource is presented in this paper. This modeling uses three concurrent processes: firstly the fabrication of the mechanical structure; secondly, the assembly of the electric motor; and thirdly, the assembly of the cars batteries. These processes were implemented in the Automation Laboratory of the the "Centro Industrial y del Desarrollo Tecnológico - CIDT SENA" located in Barrancabermeja town. The model was functionality implemented through an electro-pneumatic assembly controlled by a Siemens PLC programed with GRAFCET.