This wiring diagram manual provides detailed electrical schematics for Volvo B12M buses equipped with DH12E engines, starting from chassis number 380199. It includes comprehensive layouts of electrical systems, circuit connections, and component locations. The manual is essential for diagnosing and repairing electrical issues, offering precise guidance for troubleshooting and maintenance. This document is crucial for technicians and electricians to ensure the proper functioning and safety of the electrical systems in these bus models.