This comprehensive repair manual covers Fiat tractor models 480, 480 DT, 500, 500 DT +, 540, 540 DT +, 580, 580 DT, 640, 640 DT, 680, and 680 DT, primarily produced from the 1970s through the 1980s. These robust agricultural machines, powered by 3- and 4-cylinder diesel engines ranging from 2592 cc to 3456 cc, are known for their reliability and durability in demanding farm environments. The manual highlights the engineering quality inherent in the Fiat tractor division's heritage, providing detailed information to ensure optimal performance and longevity for these versatile workhorses. This manual serves as an essential resource for professional mechanics, agricultural technicians, and owners. It offers in-depth technical information, step-by-step repair instructions, and critical torque specifications across all major mechanical and electrical systems. Coverage includes the engine, powertrain, transmission, braking, steering, hydraulic lift unit, PTO, and electrical systems, complemented by a dedicated troubleshooting guide and essential wiring diagrams. The manual is designed to facilitate accurate diagnosis, efficient maintenance, and thorough repair, thereby minimizing downtime and maximizing the operational effectiveness of your Fiat tractor.