A wiring schematic is a line diagram of an electrical circuit showing all the components needed to
operate the circuit and the wiring paths that connect them. Back in the early days, a diagram including every
circuit on the car would only take up a few pages. Today, it can add up to a small book. That is one reason that
many schematics have been simplified into "block" diagrams, focusing on just one circuit and
showing only those elements needed by that circuit.