The Volkswagen Jetta, specifically the A5 (Mk5) generation (chassis code 1K2) produced from 2005 onwards, represents a significant evolution in compact sedan design, known for its German engineering and premium positioning. This model offered a sophisticated electrical architecture, emphasizing advanced CAN-bus and LIN-bus networking for integrated vehicle control and communication. Notable features included a range of efficient gasoline and TDI diesel engines, manual and DSG transmissions, and a focus on functional integration and modularity. The Jetta was praised for its driving dynamics, refined interior, and strong safety ratings, making it a competitive choice against other vehicles in its segment. This technical training manual is designed to provide in-depth education on the electrical system architecture and functionality of the Volkswagen Jetta A5 (Mk5). It thoroughly covers the electrical system design, including power distribution through fuse boxes and relay carriers, and the intricate communication networks utilizing CAN-bus and LIN Bus systems. The manual details various components such as control modules, electrical boxes, lighting systems, comfort and convenience features, instrumentation, diagnostic interfaces, and security systems. It serves as a vital resource for automotive technicians, electrical engineers, and diagnostic specialists seeking to understand the system logic, troubleshoot issues, and maintain the vehicle's complex electrical components.