This wiring diagram provides comprehensive electrical schematics for Volvo FM and FH trucks equipped with VAL-BAS4 and VAL-CHD2 systems. It covers models with CHID codes A678743–, B532897–, and CKD882147–. The manual includes detailed circuit layouts, wiring paths, and connections for critical components, ensuring accurate diagnosis and repair of the truck’s electrical systems, essential for maintaining optimal performance and reliability.