there is often an indicator light on a key switch of a household lighting lamp. the resistance of this kind of indicator light is extremely large, so that the current in the circuit is extremely small, so that the voltage of the electric appliance cannot reach the rated voltage at night and cannot light up. generally, there is a capacitor in this kind of indicator light because of a small the indicator light cannot tolerate 220v voltage.
installed on the dashboard in the cab, the number depends on the design. it is used to indicate related lighting, light signals, and the technical status of the working system, and to send out warning light signals for abnormal conditions.