In important and unexpected ways, the information in wiring diagrams is our most valuable diagnostic tool; so most good mechanics use them frequently for just such troubleshooting. But the diagrams reveal much more, beyond what wire goes between which components, beyond even what the electrical engineers who designed the circuits may have meant to include in their schematics. These symbols and lines can capture the electrical fundamentals of the system, what the constituent parts should do, how they work. Much of the information in a wiring diagram is implicit, so we want to understand the basis of what the diagrams represent, and we want a process of analysis we can use to go from the simple to the complicated, yet a process that can still turn the complicated into the simple when we need it. We can use wiring diagrams at a next-higher level, if we take the right approach. If, that is, we learn to learn …