The reason why the car headlight bulbs do not light up may be that the battery is seriously deficient and the wire heats up, so that the resistance of the circuit increases and the circuit is short-circuited. The contacts of the light relay and combination switch in the circuit are ablated and bonded, thereby Cannot be disconnected or connected; the fuse in the headlamp circuit is blown; because of the use of more electrical appliances, the diode and coil of the generator are burned out and the generator cannot generate electricity.t10 automotive bulb

                                                       
The specific solutions for car headlight bulbs not bright are as follows:

First, you can remove the brake light bulb to see if the filament is burned out. If the filament is intact, you can use a screwdriver and wire to scratch the brake light wire terminal against the iron while you are stepping on the brake pedal. If there is fire and the brake light does not turn on, it means that it is caused by poor grounding; If there is no fire, it means that the brake light switch may be malfunctioning or there is an open circuit in the brake light circuit.truck backup lights

In order to further find out where the fault is, short-circuit the two terminals of the brake light switch with a wire. If the brake light is on, it means that the brake light switch is faulty and should be repaired.