Isolate an Electrical Circuit

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How to isolate a circuit from a wiring diagram?  The industry term is called, creating a Block Diagram.  From a wiring diagram, it is necessary to isolate, define, or identify what a specific circuit contains.  Let’s say your tail light doesn’t come on.  To troubleshoot the circuit, one can only suspect failure within the circuit unless multiple circuits are not functioning.  Or in the case of the CB750, if only one bulb is not working, then the likely cause is the bulb, the socket, or the wires beyond the connector of the light assembly.

One thing we know, is that it takes a few components to make this circuit functional.  Let’s make a list:

1. Tail light Assembly (2 bulb set up on the CB750)
2. The power source or battery
3. The tail light comes on when the key is ON => The Ignition Switch
4. Then lets take a look at fuses. The Main Fuse protects almost all the circuits on the bike
5. More specific, on the diagram we see a 15 Amp fuse labelled [Tail-meter others].

Once the list is done, all we have to do is connect the wires between the componentslisted.  Yes, that simple.  Now, keep in mind, that not every connection will involve a wire.  We know that in the automotive industry, they use the Frame or Chassis, and the Engine as a conductor for the Negative side of almost all circuits.

So, it you were to cut out everything out that doesn’t involve that circuit, well, there it is.

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Some technical manuals do provide Block Diagrams of circuits, but most of them don’t.

With a little practice, this process becomes a second nature, and troubleshooting an organized endeavor.  A technician who can diagnose is a technician appreciated by the customers.

Those who just try parts until they find the problem, do not stay in the motorcycle field, as motorcycle parts are double or triple or more in price.  It is a common practice of the too many auto mechanics to just replace and try.