Professional mechanics use a car's fuse box diagram to understand exactly which fuses are connected to which components of a car when performing maintenance or upgrades. The diagram helps the mechanic troubleshoot specific issues, such as a malfunctioning dome light and cutting power to areas receiving work.
A fuse box diagram for a car is a document that shows the central electrical wiring of the vehicle along with the different fuses used to control the electrical current to the car's components. The diagram also conveys the type and number of watts in each fuse to help clarify replacements in the event that a fuse burns out. It is a key tool to any mechanic performing any kind of electrical work on the car because it tells her important information about the car's configuration. Many repairs require a fuse box diagram to identify what circuit controls a certain mechanism in the car and the exact type of fuse or wiring needed to replace that component.
Fuse box diagrams are also useful for mechanics that are adding in electrical components to a car, such as a built-in navigation system or an LCD television panel. The diagram tells the mechanic which circuits are capable of handling additional usage and how to access and add new wiring.