This Service Repair Manual provides comprehensive information for C7, C7.1, C7.2, C9, and C9.3 on-highway truck diesel engines. These liquid-cooled engines feature common rail fuel injection and turbocharging, with displacements of 7.0 L for the C7 family and 8.8 L for the C9 family. The C7 series offers a power range from 200 to 365 hp, while the C9 series delivers 275 to 400 hp. Emissions control is managed through systems such as ARD, DPF, and NOx reduction. Key engine components covered include the crankshaft, cylinder block, cylinder head, pistons, connecting rods, valves, camshaft, and fuel injection system. This English-language manual serves as an essential resource for maintaining and repairing these engines. It details diagnostic testing for sensors, electrical circuits, and various systems, offering expert guidance for troubleshooting and resolving engine issues. Owners, mechanics, and technicians will find detailed procedures and technical specifications necessary for ensuring optimal engine performance and longevity. The manual is compatible with Windows, Mac, tablets, and phones, providing accessible information for a wide range of users.