This wiring diagram manual provides detailed electrical schematics for Volvo B12B buses equipped with DH12E engines, covering chassis numbers from 145005 to 145639. 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.