Prefabricated timber modules are increasingly used as load-bearing structures in multi-storey residential buildings. Unlike traditional applications where they serve as non-load-bearing elements within superstructures such as steel frames, these modules must now support not only their own dead weight but also imposed loads, snow loads, wind loads, and more. This means higher need of more accurate predictions of the degree of utilization for both ultimate and serviceability limit states in various structural elements. In this study, an effective structural element based 3D finite element (FE) model initially developed and experimentally validated for small prefabricated modules has been further refined. The paper aims to validate the enhanced FE model, analyze inter-modular connection slip and shear deformations under varying loads, and identify key parameters influencing racking behavior in different module types. The model is experimentally validated against two full-size modules - one designed by platform framing and the other by balloon framing - and used to simulate various load scenarios in parametric studies. The model demonstrated satisfactory prediction of the racking stiffness and strength compared to experimental results. Furthermore, simulations revealed the influence of door opening placement and differences between platform and balloon framing on the non-linear racking behaviors. Balloon framing, in particular, offers advantages for reducing shear deformations within the module. The study also investigates the structural behavior of the inter-modular connections. The observed slip deformations in these connections can significantly affect the global racking behavior of a multi module structure. For a horizontal load F = 63.7 kN, the slip deformation of the inter-modular connections become larger than the shear displacements within the test modules.