1. Honk the horn and turn on the headlights. If there is no fire, it is the open circuit between the low voltage terminal of ignition coil and the ammeter. According to the order of ignition coil "switch" > "switch power" terminal of ignition coil > ignition switch > ammeter, the position of open circuit fault can be diagnosed according to whether there is fire or not. If the connection between the terminal and the conductor is not firm or the contact is poor, clean the terminal and tighten the fixing nut; if a section of wire is open circuit, replace the section of wire, and the replaced wire should be the same as the original wire.
2. The horn doesn't sound, and the headlamp doesn't work. Conduct a fire test at the starter terminal. If there is a fire, the fault is that the circuit between the starter terminal and the ammeter is open circuit; if there is no fire, the fault is that the battery power is insufficient or its circuit fault. If the battery is insufficient, it should be charged; if the circuit is open, it should be reconnected.
3. Use a screwdriver to test the fire on the "- terminal of the ignition coil. If there is a fire, test the fire between the movable contact arm of the distributor and the base plate. If there is a fire, it is a contact fault (such as contact ablation, too dirty, unable to close, etc.), and "platinum sand bar" can be used to grind the contact and adjust the contact gap to eliminate the fault. If there is no fire, go to the next step.
4. Fire test shall be conducted at the insulation connection post of distributor and distributor shell. If there is no fire, it is the open circuit fault of the conductor between the insulation terminal of distributor and the "- terminal of ignition coil; if there is fire, it is the open circuit fault of the conductor between the insulating support and the insulating terminal. If the power is cut off due to poor contact between the terminal and the conductor, clean and fasten the connection between the terminal and the conductor head; if a section of wire is open circuit, replace the section of wire with the same specification wire.