The electrical circuit of Honda CB400SF motorcycles is single-wire, the second conductor is «weight» - the engine and frame of the motorcycle. WITH «weight» the negative terminals of the battery and consumers of electrical energy of the motorcycle are connected. When troubleshooting motorcycle electrical equipment, you must first make sure that the fuses are in good condition and that they make good contact in the connectors of the corresponding circuit. As a rule, oxidized terminal block leads are the most common cause of electrical equipment failure.
It is important to remember that before repairing or dismantling electrical equipment, you must first remove the wire terminal from the negative terminal of the battery. It is worth remembering that improper connection of wires to the battery terminals can lead to the failure of the electronic equipment of the motorcycle. The battery itself must be serviced with rubber gloves, since the electrolyte is toxic, contact with the skin and eyes should be avoided.
When replacing circuit fuses, you must first determine and eliminate the cause of their blown. In order to avoid failure of electrical equipment, fuses with an increased rating should not be installed.