The implementation of lean construction in off-site construction is an ongoing combination aiming to improve the efficiency and reduce all forms of waste in the construction industry. Modular construction offers a high level of off-site value creation, and consequently leaner processes associated to the well-known off-site construction advantages as waste management, shorter project timeline, improved health and safety conditions for workers, better quality control, optimal material handling, and efficient working stations. Nonetheless, the on-site activities needed to connect the modules are often identified as critical sources of waste. In response, many connecting devices and models for calculations were developed in recent years, but very few present an automated locking mechanism for modular connection. While most connecting devices include the use of fasteners that need to be manually fixed to complete the connection of modules, an automated connecting device could significantly reduce the quantity of onsite activities by including an engineered mechanism that ensures self-lock. This research aims to evaluate the impact on leanness of an automated connecting device as well as to present a new plug-in self-lock device.